# It makes a village: child care and prosociality

Alessandra Cassar, Alejandrina Cristia, Pauline Grosjean, Sarah Walker

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Alessandra Cassar, Alejandrina Cristia, Pauline Grosjean, Sarah Walker. It makes a village: child care and prosociality. Journal of Economic Growth, 2025, 10.1007/s10887-025-09254-6. hal-05533531

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# It Makes a Village: Child Care and Prosociality*

Alessandra Cassar† Alejandrina Cristia‡ Pauline Grosjean§ Sarah Walker¶

February 11, 2025

## Abstract

We examine the relationship between allomaterial care (i.e., care for children by individuals other than the mother) and prosociality (reciprocity and altruism). Motivated by ethnographic evidence of a positive association between allomaterial care and societal trust across cultures, we design an economic experiment to measure the relationship between allomaterial care and cooperative behavior among 820 participants in small scale societies of the Solomon Islands. Our results show that receiving help with child care predicts higher levels of reciprocity towards the helper. This relationship remains robust for mothers even after accounting for participant fixed effects, for the nature of the relationship between mother and helper, and for other forms of mutual assistance. Moreover, help from non-relatives is associated with altruism toward strangers, suggesting a novel channel for the development of impersonal prosociality. Strengthening the case for the importance of allomaterial care for human development, we report suggestive evidence of potential socio-cognitive benefits to children who receive care from non-relatives (based on daylong recordings of 197 children analyzed using a multilingually-trained neural network), as well as societal-level benefits in terms of economic growth.

**Keywords:** Allomaterial care, Prosociality, Cooperation, Reciprocity, Altruism, Dictator game, Networks, Child vocalizations.

**JEL Codes:** I15, O15, Z13

<footnote>*We extend our deepest gratitude to the communities in Western and Choiseul provinces of the Solomon Islands for welcoming us and sharing their time with the research team. We are indebted to Fiona Burns for superb field coordination. We thank Kasia Hitczenko for sharing vocalization data, the World Bank for logistical support, Ben Botella, Myrtille Genot, Antoine Jacquet, Lauren Lamson, and Jack Skelley for research assistance, and Shaminka Portela for translation services. We are grateful to Nicolas Baumard, Chris Bidner, Leda Cosmides, Giorgio Coricelli, Sarah Blaffer Hrdy, Judith Burkart, Ernst Fehr, Martin Fiszbein, Hillard Kaplan, Federico Masera, Cristina Moya, Nathan Nunn, Carolus van Schaik, Paul Seabright, Christian Ruff, John Tooby, David Yanagizawa-Drott, Roberto Weber, and participants at seminars at CEGA Berkeley, Cooperation Colloquium, ESA, Institut Jean Nicod, Max Plank Institute, Melbourne University, UBC, UTS, USC, and University of Zürich for generous comments. Finally, we have a debt of sincere gratitude to two anonymous referees for their valuable feedback and insightful suggestions. Financial support is acknowledged from the Australian Research Council (FT190100298) by Grosjean; from the UNSW Business School, Centre for Social Impact, and Institute for Global Development by Grosjean and Walker; from USF by Cassar; from ERC by AC. All protocols were approved by the UNSW Ethics Committee (approval number HC180755).</footnote>

<footnote>†Department of Economics, University of San Francisco, CEGA and Chapman University. E-mail: acassar@usfca.edu.</footnote>

<footnote>‡Ecole normale supérieure, PSL University, EHESS, CNRS. E-mail: alejandrina.cristia@ens.fr.</footnote>

<footnote>§Department of Economics, UNSW and CEPR. E-mail: p.grosjean@unsw.edu.au.</footnote>

<footnote>¶Department of Economics, UNSW. E-mail: s.walker@unsw.edu.au.</footnote>
# 1 Introduction

Humans' exceptional capacities for cooperation (Boyd and Richerson, 2009; Tomasello, 2009; Bowles and Gintis, 2011) are recognized as the ultimate reason for our distinct cognition, technology, and culture (Gintis et al., 2005; Tomasello and Vaish, 2013; Henrich, 2016). Altruism, reciprocity, fairness, trust, trustworthiness, and punishment of free riders are among those critical preferences that enable humans to cooperate at various scales (Bowles and Gintis, 2011; Burkart et al., 2014). The motivations for these prosocial preferences, particularly in the context of large-scale cooperation and one-shot, anonymous interactions, have long been the object of investigation (Fehr and Fischbacher, 2003; Bowles and Gintis, 2011; McCullough, 2020). Recent literature has established a connection between human social organization and both the extent and the realm of cooperation. In particular, scholars have established how the norms and institutions that define marriage (Schulz et al., 2019), language (Moscona et al., 2017; Enke, 2019; Moscona et al., 2020; Bahrami-Rad et al., 2022), inheritance (La Ferrara, 2007; BenYishay et al., 2017; La Ferrara and Milazzo, 2017; Lowes, 2022) and male initiation rituals (Moscona and Seck, 2021) determine individuals' mutual obligations toward others, thus shaping cooperation within and across groups.

In this paper, we focus on another primal domain of social interactions, the social organization of child rearing, and investigate its relationship to prosocial preferences. Anthropologists have documented that across all cultures, a wide array of individuals other than the mother – allomothers, including fathers, grandparents, other relatives, and unrelated individuals – have been involved in bringing offspring to maturity, but with extensive variation in how much help different individuals provide (Hrdy, 2009; Kramer, 2010; Seabright et al., 2023). For example, individuals unrelated to the child provide little help among the Maya but up to 30% of total care among the Aboriginal Mardu of Australia (Kramer, 2010). Allomaterial care is further believed to have played a pivotal role in human demographic success (Kramer, 2010), allowing women who received assistance with provisioning and caring for children to have more offspring, who, with the additional support, had a greater chance of survival.<fnref n="1" />

The social and individual organization of child care provision may have also facilitated the development of critical social and emotional skills thought to underpin the capacity for human prosocial behavior (Hrdy, 2009). Illustrating this point and motivating our study, Figure 1 reveals a strong positive correlation between the intensity of allomaterial care and

<footnote n="1">¹The supplemental contributions of allopairs would include food provisioning, care and attention, protection, social learning, and bonding. A recent paper in economics also highlights the benefits of allomaterial care by the father for maternal mental health (Persson and Rossin-Slater, 2024).</footnote>
societal trust across the societies included in the Standard Cross-Cultural Sample (SCCS).<sup>2,3</sup>
Although the relationship holds controlling for an array of potential geographic and society-
level confounders, as shown in Section A of the Appendix, such cross-societal correlations
cannot address the possibility that causality runs in both directions, or that trust and child
care practices reflect unobserved factors, including heterogeneity across societies in other
forms of mutual assistance.

<figure><img src="image_2.png" /><figcaption>Figure 1: Correlation: Allomaterial Care and Trust in the Standard Cross-Cultural Sample</figcaption></figure>

Note: Binned scatterplot of the relationship between societal trust orientation in the Standard Cross-Cultural Sample (SCCS) and allomaterial care, controlling for region fixed effects (v200 in the SCCS: Africa, Circum-Mediterranean, East Eurasia, Insular Pacific, North America, South America), log mean yearly average rainfall (v1913), log mean annual temperature (v186), mean size of local communities (v63), presence of a belief in moralizing gods who intervene in human affairs (v238). Allomaterial care is measured by question v51 (non-maternal relationships in infancy) of the SCCS, with replies potentially ranging from 1 (care almost exclusively by the mother) to 6 (the mother has a minimal role). The measure of societal trust orientation comes from question v335, ranging from 0 (no inculcation of trust) to 10 (strong inculcation). Source: SCCS (Murdock and White, 1969). See Section A of the Appendix for more information on the SCCS and our empirical analysis.

<footnote n="2"><sup>2</sup>The Standard Cross-Cultural Sample (SCCS) is a dataset describing the socio-cultural practices of pre-industrial traditional societies from around the world, many of them observed before significant European contact or colonization (Murdock and White, 1969).</footnote>

<footnote n="3"><sup>3</sup>We provide more detail on data sources and methods for Figure 1 in Section A of the Appendix.</footnote>
To go beyond some of the empirical challenges associated with group-level comparisons of the relationship between allomaternal care and prosociality, we designed a study that combines an incentivized behavioral experiment with detailed individual survey data from a population of small-scale communities. For the experiment, we adopted a *within*-subject design of a dictator game in which participants made a series of decisions about how much of an initial endowment to share between themselves and a set of specific individuals in their network (i.e., spouse, mother, father, sister, brother, mother in-law, father in-law, friend, neighbor, and strangers from the same and distant villages, “receivers” hereafter). While the participants made numerous decisions, each time starting with a new endowment, only one decision, chosen randomly, was executed for cash payment. After the experiment, we administered a detailed survey to elicit, in addition to several socio-economic variables, information about the amount of help with child care that the receivers provide to the participant, as well as several other forms of mutual assistance.

Our experimental design allows us to conduct the empirical analysis at the level of a participant-receiver dyad and to isolate the relationship between help with child care and the prosociality of the participant independent of three sources of potential bias: (i) unobserved characteristics of the participant, such as status or personality, that could influence both how much help a participant receives and their cooperative inclination – which we account for using participant fixed effects; (ii) the genetic or social relatedness of the receiver to the participant (and their child) – which we account for using receiver-type fixed effects; and (iii) other forms of support the receiver provides to the participant – which we control for using survey measures of economic, financial, risk-sharing, productive, social, and emotional support.

While this design accounts for many dimensions of the relationship between participants and receivers, and for unobservable participant characteristics, it does not fully address the possibility that the association we capture between help with child care and prosociality may also include elements of reverse causality; that is, that the participant may strategically calibrate the amount sent to each receiver to elicit reciprocal child care in the future. To distinguish among giving motives, we introduce two treatment conditions: (i) non-anonymous giving (a measure of weak reciprocity, which may reward past favors or aim at eliciting future ones, as the receiver is told who sent the gift), and (ii) anonymous giving (a measure of strong reciprocity, which may reward past favors but cannot elicit future favors, as the receiver is not told who sent the gift (Bowles and Gintis, 2004; Gintis et al., 2008)). Furthermore, we assess altruism towards strangers, our measure of impersonal prosociality, and study how it covaries with the type of allomaternal help the subjects have received.

Our sample consists of 820 participants residing in the Solomon Islands, comprising 631
parents of young children and 189 individuals without children. The Solomon Islands provides a valuable setting to study how the social organization of child rearing influences prosociality. First, while all mothers of young children in our sample receive help with child care, the variety and fluidity of post-marital residence and inheritance structures provide variation in the nature and intensity of allomaternal care, giving our within-subject design enough leverage. For example, 84% of parents receive help from maternal relatives, 74% receive help from paternal relatives, 62% from both maternal and paternal relatives, and only 4% receive no help from relatives. 80% of parents also receive help from non-relatives, including 74% on a weekly basis or more. Second, the sample population primarily relies on subsistence horticulture, with nonexistent or limited access to factors that may confound the relationship between allomaternal care and prosociality, such as institutionalized or monetized childcare, widespread formal employment, and markets.<fnref n="4" />

Our results show that both mothers' and fathers' gift-giving in the dictator game is proportional to the amount of help with child care that the receiver provides. After controlling for both participant and receiver-type fixed effects, this relationship remains robust for mothers, highlighting the specific role of allo-maternal care in prosocial behavior. Increasing help with care from a few times a month to a few times a week (a 1 SD increase from the mean) corresponds to a 3.8% increase in altruistic giving among mothers, on average. By comparison, other forms of support (social, emotional, financial, or productive) hardly explain gift-giving in the dictator game. Controlling for other forms on support between participant and receivers does not alter the association between help with child care and prosociality.

Next, we extend our analysis to examine the relationship between allomaternal care and *impersonal* prosociality. Mothers who receive more help with child care from *non-relatives* are significantly more generous toward *strangers*, including in a one-shot, anonymous interaction. Neither help with child care provided by relatives, nor any dimension of social, emotional, financial, or productive support is associated with gift-giving to strangers. We also show that in villages where parents receive more help from unrelated individuals, subjects are more prosocial towards strangers, even when they do not have children themselves, a finding echoing the evidence in Figure 1 at a smaller, more homogeneous scale. We interpret this finding as suggestive evidence that the relationship between allomaternal care and prosociality may contribute to shaping social norms. Overall, these findings highlight

<footnote n="4">⁴Henrich et al. (2010); Falk and Szech (2013); Enke (2023); Agneman and Chevrot-Bianco (2023); Bartling et al. (2023) and Rustagi (2024) document how prosociality systematically covaries with market development and with community size. The development of markets, industrialization, and formal employment may directly influence prosociality as well as the need for working parents to solicit childcare, as shown e.g. by Bar et al. (2018), which would confound our analysis. This justifies our initial focus on small-scale subsistence communities.</footnote>
the importance of allomaterial care, particularly from individuals unrelated to the child, in fostering impersonal prosociality, even in one-shot anonymous interactions.

Lastly, we explore the implications of allomaterial care for economic development and for children’s socio-cognitive development as evidence of mechanisms, comprised of benefits to both the group and to children, supporting the prevalence of allomaterial care. A large literature in evolutionary biology and anthropology characterizes allomaterial care as critical for human demographic success, explaining both our high fertility rate and high rates of survival to reproductive age (Hrdy, 1999; Kramer, 2010). Accordingly, villages in our sample and societies in the SCCS that practice more allomaterial care have larger populations and higher population density, a relevant proxy of economic development in pre-industrial societies (Ashraf and Galor, 2011). In our sample, we also document evidence of higher wealth in villages where allomaterial care by non-relatives is more prevalent.

Turning to children, allomaterial care provides a social context in which infants and children must elicit care from adults whose care is less unconditional than parental care. In this context, children with better social skills are more likely to elicit better care (Bergmüller et al., 2007; Flinn et al., 2007; Snowdon and Cronin, 2007; Burkart et al., 2009; Hrdy, 2009; Burkart et al., 2014). We thus expect to observe a correlation between allomaterial care and socio-emotional and communication skills in children. To test this, we collected daylong recordings of 197 children of our participants using a cheap and easily scalable hardware solution, which we analyze using a multilingually-trained neural network to estimate child vocalization counts (Lavechin et al., 2020). Our approach captures children’s natural vocal behavior with minimal interference and is particularly appropriate to our context, given the multilingual environment (children in our sample are exposed to one or more of 12 different languages), the age range of the children (6 to 48 months), and the remote field conditions, with no reliable access to electricity or the internet. These childworn, daylong recordings have come to be preferred over shorter observations, which underestimate how much the child vocalizes (Lewedag et al., 1994), and over observational records, which suffer from observer effects (Bergelson et al., 2019). Previous research shows that child vocalization counts thus estimated correlate with standardized language measures (Gilkerson et al., 2018; Wang et al., 2020), which are the current best predictors of academic achievement (Pace et al., 2019).

Our findings point to the crucial role of allomaterial care by *non-relatives* as a positive predictor of child vocalizations. The results are robust to controlling for care provided by parents and other relatives of the child, other forms of support that the mother receives, total number of children in the household, and a wide range of mother characteristics, including a proxy for cognitive functions. In addition, we collected child-level measures of hormonal biomarkers for cortisol and cortisone, stress hormones that are associated with impaired
cognitive development in children (Lupien et al., 1998, 2009) and lower prosociality in adults (Haushofer et al., 2023). We find that children who receive more help from non-relatives exhibit lower levels of cortisol and cortisone, suggesting that care by non-relatives may confer additional socio-emotional benefits to children. To the extent that social skills in childhood relate to trust, as well as economic success, later in life (Algan et al., 2022; Fe et al., 2022), these findings highlight potential pathways between allomaternal care, generalized prosociality, and economic development.

This work ties into the literature on the origins of prosociality. Prosociality, in particular impersonal trust and generalized norms of sharing and fairness, is a key determinant of economic efficiency and social cohesion (see, e.g., Zak and Knack (2001) and Algan and Cahuc (2010), and Fehr and Charness (Forthcoming) for a recent review). A vast literature has sought to uncover how human social and political organization shapes cooperation and prosocial preferences, studying in particular the roles of religion and religious organizations,<fnref n="5" /> kinship and marriage practices,<fnref n="6" /> markets,<fnref n="7" /> slavery (Nunn and Wantchekon (2011)), as well as political violence and warfare.<fnref n="8" /> We focus instead on child care practices – arguably a primal aspect of human social organization. The link we observe between help with child care by *non-relatives* and prosociality provides an additional explanation for the negative relationship between the strength of kinship ties and impersonal prosociality.<fnref n="9" />

Our characterization of socio-cognitive benefits to children also speaks to the economic literature relating early life experiences to cognitive and non-cognitive development. This literature has mostly focused on either parental investment in children (see Attanasio, 2015; Doepke et al., 2019, for overviews),<fnref n="10" /> or the provision of formal early childhood education,<fnref n="11" />

<footnote n="5">⁵E.g. Norenzayan (2013); Henrich (2020); see Becker et al. (Forth.) for a review.</footnote>

<footnote n="6">⁶e.g. Banfield (1958); Alesina and Giuliano (2010, 2011); Ermisch and Gambetta (2010); Alesina and Giuliano (2014); Alesina et al. (2015); Enke (2019); Ghosh et al. (2021); Bahrami-Rad et al. (2022); Schulz et al. (2019); Schulz (2022).</footnote>

<footnote n="7">⁷E.g. Henrich et al. (2010); Agneman and Chevrot-Bianco (2023); Bartling et al. (2023); Rustagi (2024).</footnote>

<footnote n="8">⁸E.g. Vugt et al. (2007); Yuki and Yokota (2009); Voors et al. (2012); Cassar et al. (2013); Rohner et al. (2013); Bauer et al. (2014); Mironova and Whitt (2021); see Bauer et al. (2016) for a review.</footnote>

<footnote n="9">⁹In particular, the dislocation of kinship-based institutions under the marriage and family policy of the Christian Church has been linked to the evolution of cooperation and growth in Western Europe and in the United States (Greif and Tabellini, 2017; Enke, 2019; Henrich, 2020; Ghosh et al., 2021; Bahrami-Rad et al., 2022; Schulz, 2022). The demise of clans and kinship networks would have pushed parents to seek help with child care from non-relatives, igniting the kind of prosociality we document in this paper.</footnote>

<footnote n="10">¹⁰Papers in adjacent disciplines have investigated the role of grandparents (Hawkes et al., 1998; Sear and Mace, 2008; Danielsbacka et al., 2011) and older siblings, in particular sisters (Weisner et al., 1977; Turke, 1988). Consistent with evidence from developmental psychology (e.g., Havron et al., 2019), a recent study in economics documents better vocabulary and fine motor skills for children with older sisters (rather than brothers) in Kenya (Jakiela et al., 2020), although recent evidence suggests that this result may not be universal (Havron et al., 2022).</footnote>

<footnote n="11">¹¹See Cunha and Heckman (2007); Baker et al. (2008); Heckman (2013); Heckman et al. (2013); Felfe and Lalive (2018); Cornelissen and Dustmann (2019); Bernal et al. (2019); Cappelen et al. (2020); Fort et al.</footnote>
with possible interactions between the two (Agostinelli et al., 2019; Agostinelli and Wiswall,
forth.). We highlight instead the importance of a wider network of informal caregivers, in-
cluding extended family and unrelated individuals. Yet, our evidence is consistent with the
documented cognitive and non-cognitive benefits of daycare over exclusive parental care.¹²
Our work also contributes to an emerging literature on the importance of the social environ-
ment for the development of children’s cognitive skills and social preferences.¹³ While this
literature primarily studies child and adolescent peer and friendship groups, we study the
broader social environment of adults involved in the rearing of much younger children.

Finally, we contribute to a large and growing literature in the social sciences on the role of
social and economic networks in low-income economies (Breza et al., 2019). Family, acquaint-
ance, friendship, productive and risk-sharing networks are routinely elicited by researchers
and policy makers and relied upon to facilitate the take-up and diffusion of important policy
tools, such as micro-finance (Banerjee et al., 2013), agricultural technology (Beaman et al.,
2021a), entrepreneurship or employment programs (Field et al., 2016; Beaman et al., 2018),
public health interventions (Kim et al., 2015; Alexander et al., 2022), or poverty-alleviation
programs (Beaman et al., 2021b). Our findings on the relative importance of help with child
care compared with other social, risk-sharing, and productive networks as a source of proso-
ciality and socio-cognitive benefits to children, highlight child care networks as a crucial yet
understudied dimension of social networks in low-income economies.

The rest of the paper is organized as follows. The next section describes the experimental
design and the data. Section 3 reports the estimation strategy and studies the relationship
between allomaternal care and prosociality. Section 4 discusses the socio-cognitive bene-
fits to children while Section 5 investigates the relationship between allomaternal care and
development. Section 6 concludes.

(2020); Fryer Jr et al. (2020); Attanasio et al. (2022b); Agostinelli et al. (2022); Bjorvatn et al. (2022).

¹²Cunha and Heckman (2007); Heckman (2013); Heckman et al. (2013); Attanasio et al. (2022b) and Bjor-
vatn et al. (2022) document the long-term advantages in cognition, educational achievement, non-cognitive
skills and earnings associated with the provision of early daycare among disadvantaged communities in the
US, Latin America, and peri-urban areas of Uganda. Felfe and Lalive (2018) and Cornelissen and Dustmann
(2019) provide consistent evidence in high-income countries other than the US, although negative effects
due to the lower intensity of one-on-one interactions or low service quality are highlighted by Baker et al.
(2008); Bernal et al. (2019) and Fort et al. (2020). Recently, Cappelen et al. (2020) documents how childcare
causally influences children's prosocial preferences.

¹³See Chetty et al. (2016); Agostinelli (2018); Chetty and Hendren (2018); List et al. (2019); Agostinelli et al. (2020); Cappelen et al. (2020).
# 2 Data

## 2.1 Sample

We conducted our data collection from June to August 2019 among a sample of 820 participants, living in 44 villages across two provinces, Western and Choiseul, of the Solomon Islands.<fnref n="14" />,<fnref n="15" /> The villages in our sample are small, coastal lowland communities that depend mainly on subsistence horticulture and fishing for their livelihoods. Only 4.85% of respondents in our sample derive any income from paid work. On average, people in our sample work in their gardens a couple of times a week and sell goods in the market less than once a month. In addition, men fish a couple of times a week and women a few times a month. An average village consists of 87 households and 441 people, most of whom have no access to grid electricity, running water, or improved sanitation.<fnref n="16" /> 65% of villages do not have a market, so that market activity, for the majority, takes place in a village different from the one of residence. The main mode of transport is by ship or outboard canoe, and, in general, access to roads is extremely limited. The average travel time between the villages in the sample and the provincial capital is six and half hours and the average travel time to the country's capital city, Honiara, is two and a half days, leaving most communities isolated from major market centers.

To construct our sample, we first selected a subset of villages with whom we had an established relationship through previous work (BenYishay et al., 2017; Beath et al., 2018). Upon arriving in a village, we held a meeting with the village elder to introduce the study and obtain consent for our research. Village elders then organized a public meeting with community members. We randomly selected participants among those present via public lottery according to the following criteria: five couples (i.e. five women and five men partnered with one another, with both present at the meeting) with at least a child between the (target) ages of 18 months and four years, and ten other individuals (stratified by gender)<fnref n="17" />

<footnote n="14">¹⁴The Solomon Islands are an archipelago of over 900 islands in Melanesia with a total population of around 700,000 people. Choiseul is one island. Western Province consists of a handful of islands that are well connected to one another.</footnote>

<footnote n="15">¹⁵There were two survey teams in Western and one in Choiseul, each consisting of two research assistants and two local enumerators, with at least one female and one male, who could speak English, Pijin (the vernacular), and at least one local language. The composition of the teams did not change over the course of the data collection.</footnote>

<footnote n="16">¹⁶According to our survey, electricity is “used by most households” in 8% of villages. Only slightly over half of the households have a water tank, and only 25% of the villages always have enough drinking water for all households. 75% of households use the bush, the river or the sea as their “main type of toilet” and only 4.25% of households have access to a flush toilet.</footnote>

<footnote n="17">¹⁷These participants could be partnered or not and/or have children or not. 60.72% of them are in a relationship (married, living with someone but not married, engaged, or have a boyfriend/girlfriend) and 59.27% of them have children. Among people with children, only 19.27% are single or divorced.</footnote>
for a total of 20 participants per village. In our couple sample, we interviewed both wife and husband to have precise measures of both mother and father care and to validate the questions on child care from direct relatives, in-laws, and acquaintances.<fnref n="18" /> Our protocol was translated (and back translated) in Pijin, the lingua franca of the Solomon Islands, and our local enumerators, who spoke several of the local languages as well as Pijin, conducted the experiments and surveys under the supervision of our research team.

## 2.2 Experimental design and survey instruments

To measure prosocial preferences, we adopted a within-subject design in which each participant played a series of dictator games involving the allocation of an endowment of SI$40 ($5 USD at the time of our study, which is equivalent to the average daily GDP per capita) between themselves and a series of receivers (see Instructions accompanying this paper).<fnref n="19" /> Each game, each time with a new endowment of SI$40, required the participant to choose to send SI$0, SI$10, SI$20, SI$30, or the entire amount SI$40 to a specific receiver. Receivers included relatives, in-laws, acquaintances, and strangers. Specifically, they were: a random person in a distant village, a random person in the participant's own village (hereafter, “strangers”), and the participant's: spouse, mother, mother-in-law, father, father-in-law, sister, brother, neighbor, and close friend.<fnref n="20" /> To keep each choice salient and prevent portfolio effects, only one decision, chosen at random at the end of the session, was implemented for cash payment. To ensure that the participants understood this method, prior to the actual experiment, they practiced drawing one number at random, linking it to the corresponding decision/receiver, and answering questions about how much money they would gain and how much money would the receiver gain if that choice was the one ultimately implemented for cash.

The games were administered under two treatment conditions and played sequentially. First, participants were asked to make each of their allocation decisions towards each receiver non-anonymously (i.e., if this was the condition/receiver randomly drawn for payment, the money destined to the receiver was to be put in an envelope to be delivered by the subject directly to the participant, knowing that the research team would subsequently contact the receiver and ask about receiving the gift); and then, anonymously (i.e., the enumerators

<footnote n="18">¹⁸It could be the case that, for example, one parent has no precise idea how much their in-laws provide, or systematically overestimate what their own parents provide. Interviewing both wife and husband enables us to gauge these potential biases. As shown in Table B2, mothers' and fathers' reports are consistent with one another.</footnote>

<footnote n="19">¹⁹To minimize spillover, where a participant's choices may be influenced by talking with others, the experiment was conducted on the same day and at the same time for all participants living in a village.</footnote>

<footnote n="20">²⁰Participants also had to decide how much money to give to their Church and to one of their children, but these choices are not included in this analysis as our focus, here, is on the main providers of childcare among the adults in a participant's network.</footnote>
would deliver the gift to the receiver without saying who sent them the money, but making it clear it came from an anonymous donor as part of the research project).<sup>21</sup> We include giving under both conditions to capture possibly distinct motives for prosociality.

In the case of dictator game receivers that are known to the subject, we distinguish between: (1) weak reciprocity, that is, non-anonymous giving motivated not just by gratitude for help received in the past, but also by the prospect of plausible future interactions, and (2) strong reciprocity, that is, anonymous giving towards relatives and acquaintances who could have helped before, but, given the secrecy of the gift, could not be incentivized to reciprocate further.<sup>22</sup> In the case of unknown receivers, i.e., strangers in the same or distant village, we distinguish between: (3) weak altruism, that is non-anonymous giving possibly motivated by the possibility of future interactions, and (4) strong altruism, that is anonymous giving towards complete strangers (the condition usually implemented in lab and field dictator game experiments).<sup>23</sup>

One concern is that anonymity may not be believed to be enforceable in practice, when a receiver is well-known to the subject. For example, a husband receiving a payment, even anonymously, may suspect the payment to come from his wife in the case she was also a participant in the experiment, or a participant could have planned from the beginning to tell the receiver who sent the gift regardless of the giving condition. Several considerations mitigate this concern, although they do not eliminate it entirely. Given the small-scale nature of the villages, a participant's husband could also be the brother of another participant. Moreover, the inclusion of “strangers” as a potential recipient reduced the probability that a receiver would suspect a particular family member or a friend, since anybody could be the “stranger” (in the same village condition) of another participant. Overall, given these design choices and field conditions, and given that only one allocation per participant was paid out for real, a husband receiving an anonymous payment (in itself a small probability event) could have no certainty as to who had sent that payment, and any attempt at signaling who sent the payment would be cheap talk.<sup>24</sup> Despite these measures, a possibility remains that

<footnote n="21"><sup>21</sup>The design of conducting dictator games both anonymously and non-anonymously is similar, for example, to Leider et al. (2009).</footnote>

<footnote n="22"><sup>22</sup>While the literature has not settled on a unique use of the terms, we use the terminology of strong reciprocity in the sense of Gintis et al. (2008), as the “propensity, in the context of a shared social task, to cooperate with others similarly disposed, even at personal cost” (p.243). As argued further in Bowles and Gintis (2004), “Strong reciprocity is altruistic, conferring group benefits by promoting cooperation” (p.18). We then adopt the term weak-reciprocity in the non-anonymous condition to known individuals to recognize that sending a gift may be due, in addition to reciprocal motives as previously defined, to self-interested intentions to encourage the continuation of a cooperative relationship. We adopt similar definitions for altruism.</footnote>

<footnote n="23"><sup>23</sup>For example, see Ramos-Toro (2023) as a recent example of a field experiment interpreting giving to strangers as altruism.</footnote>

<footnote n="24"><sup>24</sup>To go one step further and prevent any disappointment and argument among spouses, we added a</footnote>
the participants did not completely believe that anonymity could be fully enforced, in which
case the amounts would be very similar across the two conditions.

After the games, the enumerators conducted a 30-minute survey with each participant.
The questionnaire elicited demographic, social, and economic information about the partici-
pant (see Table D1 in Appendix for detailed variable description), including cognitive ability,
religiosity,²⁵ basic time use data, and past exposure to violent events,²⁶ as well as specific
questions about the relationship between the participant and each receiver in the dictator
game, including measures of economic, productive, and emotional support provided by the
receiver to the participant and, because religion is an important part of daily social lives
in the Solomon Islands, whether the receiver and the participant attend the same church.
These questions were adapted from existing questionnaires on social networks (e.g. Banerjee
et al. (2013); Kim et al. (2015)). The innovation is to add a question on the help with child
care that the receiver provides to the participant.

The frequency of child care provided by each receiver to the participant is measured as
follows: (0) never; (1) less frequently than once a month; (2) more frequently than once a
month; (3) once a week; (4) a few times a week; (5) every day, a little bit; (6) or every day, for
a large part of the day. In our analysis, we standardize this measure to mean zero, standard
deviation one, to interpret relative increases in the amount of help with child care. We
measure emotional support by a question asking how often the participant and the receiver
spent time together “to talk about [the participant’s] feelings, joys, and sorrows”. The answer
scale was identical to the one used for the frequency of help with the children. Questions
about economic and productive support ask whether the participant would go to the receiver
if they needed to borrow: (i) a small amount of money, (ii) a large amount of money (yes/no
answers), and (iii) how frequently the receiver helps them with cultivating their garden or
goes fishing with them (answer scale identical to the one used for the frequency of help
with the children and for emotional support). Answers to the question about whether the
participant and receiver attend the same church are either yes or no.

random amount to the amount sent in the spousal condition (so no spouse could know exactly how much was sent by the other) and this was stressed during the instructions.

<sup>25</sup>Almost all of our participants (96.04%) report engaging in religious activity (praying or attending mass). We proxy religiosity by the *frequency* at which respondents engage in religious activity, measured on the same scale as other activities (i.e. on a 7-point scale, from “never” to “every day, for a large part of the day). The mean is 3.30 and the s.d. is 1.34.

<sup>26</sup>The Solomon Islands experienced episodes of ethnic violence between 1998 and 2003. Most of the violence occurred in the main island of Guadalcanal but other provinces, and particularly Western province, also experienced sporadic but intense violence. We ask participants whether they have ever “witnessed organized violence or warfare with people from another village” (mean: 0.44, s.d.: 0.50)
## 2.3 Child socio-cognitive and socio-emotional indicators

### 2.3.1 Child vocalizations

The number of child vocalizations was estimated from child-centered long-form recordings collected using a wearable device, an increasingly used technique in early language development research (Lavechin et al., 2021).<fnref n="27" /> Each recorded child wore a t-shirt fitted with two small breast-pockets, into which a pair of USB voice recorders was inserted. Two recorders were used because in such field conditions, with high humidity and variable temperatures, some devices stop functioning. The recorder then functioned continuously until the battery ran out, except if extracted from the t-shirt and turned off, which the family could do if they decided to exercise their right of withdrawal from the study, or at the end of the day, when the research team collected the equipment. This resulted in 384 recordings for 197 children, lasting on average 15.3 hours (SD 4.5 hours, range 0.11 minutes - 24 hours). Since we expect this heterogeneity to affect the precision of our estimates, we weigh each observation by the recording duration of each USB in our empirical specifications.

Each recording was analyzed with a Voice Type Classifier (VTC, Lavechin et al. (2020)), an end-to-end neural network, which for every 10 ms frame returns whether the key child (i.e., the child wearing the recording device) was vocalizing or not. A vocalization is then defined as a sequence of frames where the child vocalizes. VTC was trained with a combination of various child-centered corpora of children aged 0-4 years exposed to one or more of a variety of languages (including Minn, French, Jul'hoan, Tsimané, English, and several others, in approximate order of data quantity). Importantly, these corpora included children growing up in multilingual settings, as well as languages spoken in the Pacific, with a wide variety of typological characteristics. The multi-corpus training was done to improve the generalizability of the network to unseen data sets. The corpora were divided internally into independent training, developmental, and testing sets. As reported in Lavechin et al. (2020), F-score performance on the test set of this multilingual corpus was 77.3% for recognizing the key child.<fnref n="28" /> In addition, that study also reports on performance for a wholly independent,

<footnote n="27">²⁷In urban conditions, a hardware-software combined solution called LENA is frequently used (Gilkerson et al., 2017; Cunha et al., 2024; Dupas et al., 2023). LENA was suboptimal in our setting for two key reasons. First, the lack of electricity and internet connection found in these remote communities meant that the licenses promoted by LENA were inappropriate. To recover the audio-recordings, one needs to connect the recording device to a computer, have enough power and internet to extract and upload the recording (which is meanwhile stored in a proprietary format) before the recording device can be used again. Second, LENA's software was trained in urban conditions among monolingual American English learners, which raises questions about whether the software would be sufficiently accurate in our population of largely multilingual infants growing up in rural conditions (and exposed to one or more of 12 different languages: Avaso, Babatana, Marco, Marovo, Pidjin, Roviana, Senga, Simbo, Sisinga, Ughele, Vaghua, Varisi).</footnote>

<footnote n="28">²⁸F-score is a measure of accuracy that goes from 0 to 100%, higher is better. In technical terms, it is the harmonic mean of precision and recall, with precision being the percentage of retrieved elements that</footnote>
unseen, test set comprised on monolingual English learners, for which LENA performance
was also available. In that comparative dataset, LENA's performance for the key child was
54.9%, whereas the VTC scored 25% higher, at 68.7%. We also checked the performance of
VTC in a small subset of data analyzed in the present paper. About 87 minutes of audio were
annotated by research assistants who were unfamiliar with the language and the families that
were recorded, which may have a negative impact on the accuracy of their annotations, so
that performance of VTC is under-estimated. Nonetheless, performance was good, at 61%.

VTC outputs a text file indicating at which points of the multi-hour recordings the key child vocalized. Following standard practice in the field (Cristia et al., 2020), we counted the number of vocalizations attributed to the key child over the whole recording. We then divided that by the length of the recording, to control for variation in recording length.

Recording young children’s vocalizations through wearables is a promising method to assess language development. Long-form recordings have several advantages, including capturing the child’s vocal patterns in their natural environment and being able to accumulate a great amount of data easily. However, this also means that the audio recording is harder to process than an audio recording gathered in more manicured and stable conditions. Automatized algorithms attempt to classify child vocalizations into crying, laughing, canonical, and noncanonical, but precision is still a challenge (Schuller et al., 2019; Semenzin et al., 2021). We address the possibility that our vocalization counts confound actual speech and crying in several ways. First, we rely on manual annotations from lab specialists to code the nature of vocalizations in a random subset of our data. In line with established research,<fnref n="29" /> cries constitute a small proportion of vocalizations: only 3.20% of the segments corresponded to crying. The majority of segments were speech-like (93.2%), and laughing amounted to a similar proportion to crying (3.01%). Second, we measure distress by analyzing hormonal biomarkers, explained in the next section.

2.3.2 Cortisol and Cortisone

We collected a direct measure of child socio-emotional well-being based on hormonal biomark-
ers for stress hormones. In Western province,<fnref n="30" /> we invited the selected married participants

<footnote>are true positives, and recall the percentage of relevant elements that were indeed retrieved. For instance, if
the "key child" category has a precision of 70%, that means that 30% of the times that the system returned
"key child", it was wrong, and it was a different category (e.g., female adult). A recall of 70% means that
30% of the times the key child vocalized, the system did not spot this (e.g., missed the speech altogether or
put it in the "female adult" category).</footnote>

<footnote n="29">²⁹Among a sample of either children younger than children in our sample (4-18 months) or slightly older children (11-53 months) but who were diagnosed with Angelman syndrome (a genetic disorder causing speech delays and intellectual disability), related research has shown that 72.89% of automatically identified segments were speech-like, 5.23% crying, and 1.65% laughing (Semenzin et al., 2021).</footnote>

<footnote n="30">³⁰We could not collect hair samples from Choiseul Province for logistical reasons, as our field team had to carry all materials and food on a round-trip around the island and did not have access to any storage</footnote>
in each village to provide hair samples for the mother and child, following the procedure
adapted from Wright et al. (2018). After all field work was completed, 102 mother-child
pairs of hair samples were sent to a laboratory and evaluated for levels of cortisol and corti-
sone.

We specifically collect hair samples, rather than saliva, to circumvent known issues with
collection timing and storage of saliva samples (Pruessner et al., 1997). Levels of cortisol
among the children in our sample are, on average, 6 pg/mg, which is commensurate with
levels documented in a Dutch sample of similar-age healthy children (de Kruijff et al., 2020).

Levels of cortisol and cortisone provide measures of child socio-emotional wellbeing, and
have been used in the literature to study stress and wellbeing responses of children to care
environments (Groeneveld et al., 2010). Higher levels of cortisol and cortisone in children
have detrimental developmental consequences for child cognitive and health outcomes. They
are associated with the over-activation of the hypothalamic pituitary and adrenal glands,
which may result in unfavorable developmental consequences, including suppressed immune
responses and impairments to brain development (Lupien et al., 1998, 2009). Haushofer
et al. (2023) show that increased cortisol is associated with lower prosociality of adults in
laboratory settings, although the link has not yet been tested for children.

**2.4 Descriptive statistics**

**2.4.1 Sample statistics**

Appendix Table B1 presents the summary statistics for our sample (N=820). Half of the
participants are women. On average, participants are nearly 31 years old and 77% have
children (N parents=631). The average age of the target child is 25.41 months, in line with
our recruitment protocol, with 2 siblings on average. Slightly less than half of the children
are female (47%). On average, participants have three relatives living in the same village.

Only 38% of the participant sample has completed secondary school, reflecting the low
educational opportunities for people in the Solomon Islands, while on a test of cognitive
ability (similar to Raven's Test), participants answered just over 50% of questions correctly
(12.79 out of 24), which is slightly higher than mean scores from samples in other low-income
settings (Brouwers et al., 2009).

**2.4.2 Who helps with child care**

Summary statistics reveal the extent to which help with child care is prevalent in these
communities. On average, parents of young children receive some form of help with care from
more than seven different people. In terms of frequent help with care, 52% of participants

<footnote>solution.</footnote>
receive daily help from their spouse and 62% from someone other than their spouse, and a similar proportion of respondents provide care for other people's children.

Our design enables us to capture how much help is provided by different people, relatives and not, as reported by both mothers and fathers.<fnref n="31" /> Figure 2(a), based on the statistics reported in Appendix Table B3, illustrates three main patterns. First, parents of the child provide significantly more care than others, with fathers providing substantial care (more than the next top helpers, grandmothers). Second, women provide more care than men: mothers more than fathers, grandmothers more than grandfathers, and sisters more than brothers. Third, help with child care relies substantially on the support offered by unrelated but well-known individuals, namely friends and neighbors. Overall, these findings are consistent with a large literature linking help to both genetic and social proximity (Barrett et al., 2002; Kasper and Mulder, 2015).

Patterns are remarkably similar across mothers and fathers, with a few exceptions. Mothers provide more care than fathers; and mothers report more help from friends and neighbors than fathers.<fnref n="32" /> Friends and neighbors help mothers as much as the child's grandmothers.

Since childcare from different helpers is likely to be correlated and plausibly depends on factors specific to each household, such as the number of children they have, their ages, the wealth of the family, the presence of relatives in the village and the specifics of their economic survival, in Appendix Table B4, we examine the determinants of help with child care to assess how systematic these correlations are. The main determinant of help from relatives is the presence of relatives in the village. The intensive margin of productive activities is an important predictor of help received with child care for mothers, but not for fathers. Mothers who work more in their gardens, fish more, or sell more frequently in markets outside of their village receive no extra help from their husbands but they receive more help from friends and neighbors. Another interesting pattern is that mothers who receive more help with child care also tend to take care of their own child more frequently. This highlights that in the context of the horticultural societies that we study, with limited involvement in outside economic activities, child care is a social activity. This stands in contrast with industrialized countries, where mothers are generally more socially isolated

<footnote n="31">³¹Surveying both mother and father enables us to validate how accurately people report help with child care. Mothers and fathers report similar levels of help from the mother's parents, but fathers tend to overestimate help by their own parents, compared to their wives' answers. However, once we control for other ties with the fathers' parents (e.g., economic and productive help and socio-emotional support), the difference between mothers' and fathers' reports of child care help from paternal grandparents is no longer statistically significant and small in magnitude. These results are included in Table B2.</footnote>

<footnote n="32">³²This discrepancy suggests that fathers may have imperfect information about the help that friends and neighbours provide when the baby is left in the mother's care. An alternative, not mutually exclusive hypothesis, would be that contrary to the grandparents, the friends of the father are not necessarily the same as the friends of the mother.</footnote>
(Konner, 2017) and where formal childcare can substitute for parental care.

Further more, in Appendix Table B5, we show how help with child care correlates with other dimensions of the relationship between participant and receiver. People who help with child care also tend to provide emotional support, go to the same church, help with garden work and offer financial support. While help with child care is not perfectly predicted by these other dimensions of social and economic support, controlling for them may be important to isolate the influence of allommaternal care on giving in the dictator games.

### 2.4.3 Reciprocity and Altruism towards relatives and others

Figure 2(b) illustrates the average share of the dictator game endowment given to each receiver, separately for the non-anonymous (weak reciprocity), anonymous (strong reciprocity), and giving to strangers (weak and strong altruism) conditions (see the full statistics in Appendix Table B6). Patterns of giving follow distinct tiers, which could be explained, only in part, by kinship. Mothers and fathers give the most to their spouse and their own parents, with shares hovering around 50% or more. One notable difference is that men give significantly more to their wives than what they receive from their wives (respectively 55.6% vs. 48%; p-value=0.001). Participants give similar amounts (around 36%-39%) to their own siblings and to their in-laws. Friends, neighbors, and strangers all receive non-negligible shares. Friends and neighbors receive around 32% of the endowment, significantly less than what is given to siblings and in-laws, but significantly more than what strangers receive (around 28% in the same village and 26% in the distant village).

With respect to differences between the non-anonymous and anonymous conditions, we find that the prospect of future exchanges overall motivates people to give more, but the magnitude of the difference is small (respective averages: 38.2% vs. 37.2%; p-value=0.019).<fnref n="33" />

## 3 Allommaternal care and prosociality

Simple correlations between cooperative behavior in the dictator game and help with child care may be confounded by both the relatedness of the receiver to the participant and their child (e.g., spouse, relatives, and non-relatives),<fnref n="34" /> as well as factors that influence both the amount of help a participant can elicit and their prosocial inclinations (due to status, personality traits, or other unobserved factors). We first discuss how our experimental setup enables us to address these empirical issues and present our results. We then document how allommaternal care, specifically by non-relatives, corresponds to impersonal prosociality and

<footnote n="33">³³See Appendix Table B6 for a breakdown by gender and receiver, this difference is statistically significant only in a few cases.</footnote>

<footnote n="34">³⁴Here, we note that the relatives of one's spouse are not genetically related to the participant, but they are related to the joint child, so we assimilate them to relatives.</footnote>
socio-cognitive outcomes in children.

## 3.1 Estimation strategy

We estimate the following specification at the level of a participant-receiver dyad in the dictator game, which allows us to exploit within-participant (i) variation in the share of the endowment ($y_{irg}$) transferred to each receiver (r), as well as variation in the amount of help with child care ($Care_{ir}$) provided to the participant by each specific type of receiver (e.g., spouse, mother, father, mother-in-law, father-in-law, brother, sister, friend or neighbor):

$$y_{irg} = \alpha + \beta_1 Care_{ir} + \beta_2 Care_{ir} * R_g + \delta R_g + X'_{ir} \Gamma + \rho_i + \mu_r + \varepsilon_{irg} \quad (1)$$

where $Care_{ir}$ captures the frequency of help with child care provided by receiver r to participant i, which we standardize to mean zero, standard deviation one.<fnref n="35" /> The term $R_g$ is an indicator variable for the non-anonymous giving condition. We allow the coefficient associated with $Care_{ir}$ to vary across weakly reciprocal and strongly reciprocal motives by including an interaction between $R_g$ and $Care_{ir}$. The term $X_{ir}$ is a vector of dyad-specific attributes capturing other dimensions of the relationship between i and r, including risk-sharing, emotional support, productive help, and attending the same church. The variable $\rho_i$ is a vector of participant fixed effects, and $\mu_r$ a vector of receiver-type fixed effects. We do not include individual covariates, since $\rho_i$ absorbs all participant-level characteristics.

The direction of causality is implicit in the model, since allomaterial care by different caregivers is pre-determined at the time of our experiment. Moreover, our anonymous treatment removes the possibility that participants may treat transfers strategically so as to elicit more care in the future. However, any raw correlation between $Care_{ri}$ and $y_{irg}$ could still be confounded by a number of factors. First, a participant's prosocial inclinations could be systematically correlated with how much help others are willing to provide. Others might be willing to help, for example, because the participant, or their child, are particularly agreeable and prosocial or have higher status. Similarly, more prosocial individuals or those with higher status may be more inclined to transfer higher shares in the dictator game. To address this, the participant fixed effects ($\rho_i$) in Equation (1) capture any unobservable characteristics of a given participant that may be associated with prosociality and the amount of help with child care they receive.

Second, a certain type of receiver may both provide more help with child care and receive larger gifts in the dictator games for reasons unrelated to any causal relationship between these two variables. Relatives, for example, may both receive a greater share of the endow-

<footnote n="35">³⁵Note that we only observe the amount of help with care that the receiver provides to the participant, and not the amount that the participant provides to the receiver.</footnote>
ment in the dictator game and provide more child care exclusively because of their genetic
relatedness to the participant and their child. Receiver-type fixed effects ($\mu_r$) capture the
specificity of the relationship between a given receiver and the participant (or their child)
that could drive both gift-giving and child care provisioning. We include a separate fixed
effect for each type of receiver (e.g. spouse, mother, father, mother-in-law, father-in-law,
brother, sister, friend, neighbor) and add a separate fixed effect to account for the fact that
for 17% of the individuals in the sample, the spouse is not the biological parent of the child.

Last, the provision of child care could be systematically correlated with other forms
of help that the receiver provides to the participant. We elicit other dimensions of this
relationship, including economic, productive, emotional, and social support, and check that
our results are robust to accounting for their potential influence on gift-giving by including
them as additional controls in $X_{ir}$.

The parameters of interest in Equation (1) are $\beta_1$ and $\beta_2$. These coefficients isolate
the increase in dictator game transfers associated with additional help received with child
care, after controlling for participant fixed effects, the specific type of relationship between
participant and receiver (e.g. specific family member, friend), and other dimensions of the
relationship between participant and receiver that vary at the dyad level, including the
intensity of emotional support and economic risk sharing. When the full set of fixed effects
and controls are included, the remaining variation comes from the fact that some receivers
provide more help with child care than others for reasons that are orthogonal to their genetic
or social relatedness to the participant, to the participant's characteristics, and to the other
dimensions of their relationship to the participant that we capture (e.g. emotional, economic,
productive, or attending church together). For example, the friend of one participant may
help more than the friend of another because they like children more. A neighbor may have
children similar in age to the participant's children, and hence be more inclined to provide
child care than a neighbor without them.

Because we only exploit variation in transfers across receivers for a given participant, our
design is also insulated from potential confounds such as experimenter effects, social desir-
ability bias, or cognition, which could influence how a particular individual would generally
behave in the experimental game.

## 3.2 Help with child care, reciprocity and altruism

Results displayed in Table 1 show that gift giving in the dictator game is positively correlated
with child care help, both for mothers (Col. 1) and fathers (Col. 6). Columns 2-5 for mothers
and 7-10 for fathers add participant and receiver-type fixed effects, first separately and then
together, with Columns 5 and 10 displaying the results of estimating Equation (1).
For anonymous giving, the coefficient associated with help with child care ($\beta_1$) drops in magnitude between Columns 1 and 2 (mothers), and 6 and 7 (fathers), when we add participant fixed effects, suggesting positive selection into receiving more help with child care for more prosocial individuals. The coefficient $\beta_1$ drops by an even larger magnitude when we add receiver-type fixed effects (Columns 3 and 8), especially for fathers. This is unsurprising and reflects the fact that the specific nature of the relationship between participant and receiver determines both how much help each receiver provides and how much the participant gives them. This is confirmed in the descriptive patterns in Figure 2, which shows that specific individuals in the participant's network, for example the participant's mother, systematically provide more help and receive larger gifts.

Accounting for both participant and receiver-type fixed effects, $\beta_1$ remains statistically significant only for mothers (Column 4), highlighting the specificity of allomaterial care in eliciting prosociality. These results, however, may be due to the fact that help with child care correlates with other dimensions of support, and that receiving help in any dimension elicits greater prosociality. To address this, we include controls for other dimensions of social, emotional, productive, and economic support in columns 5 and 10. Only emotional support elicits higher gift giving by mothers,<fnref n="36" /> while $\beta_1$ and $\beta_2$ are unchanged in magnitude.<fnref n="37" /> The coefficient on *Child care* remains statistically significant and similar in magnitude when these controls are included.

<footnote n="36">³⁶We cannot reject the null hypothesis that the coefficient for *Emotional support* is equal to the coefficient for *Child care* (p-value 0.54).</footnote>

<footnote n="37">³⁷The difference in $\beta_1$ across specifications in Columns 4 and 5 is not statistically significantly different from 0 (P-value: 0.30).</footnote>
<figure><img src="image_3.png" /><figcaption>Figure 2: Help with care and cooperation in the dictator game</figcaption></figure>

Notes: N=374 mothers and 257 fathers. In panel (a), bars represent the average amount of help with care that participants receive from the individuals in their network reported as: (0) never, (1) less frequently than once a month, (2) more frequently than once a month, (3) once a week, (4) a few times a week, (5) every day, a little bit, or (6) every day, for a large part of the day. Stars represent differences between mothers and fathers (** *p*-value < 0.05, *** *p*-value < 0.01 ). In panel (b), bars represent the average share of the dictator game endowment given to each receiver (each time from a new SI$40 endowment). Stars represent differences between giving in the anonymous and non-anonymous conditions (** *p*-value < 0.05, *** *p*-value < 0.01 ).
<table><caption>Table 1: Allomaterial care and giving in the dictator game</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th><th>(9)</th><th>(10)</th></tr><tr><th></th><th colspan="5">Mothers</th><th colspan="5">Fathers</th></tr></thead><tbody><tr><td>Child care</td><td>0.038***<br>(0.007)</td><td>0.030***<br>(0.005)</td><td>0.027***<br>(0.007)</td><td>0.015***<br>(0.005)</td><td>0.012**<br>(0.005)</td><td>0.056***<br>(0.007)</td><td>0.045***<br>(0.005)</td><td>0.030***<br>(0.008)</td><td>0.006<br>(0.005)</td><td>0.002<br>(0.005)</td></tr><tr><td>Child care X Non-Anonymous</td><td>-0.008*<br>(0.005)</td><td>-0.008*<br>(0.005)</td><td>-0.008*<br>(0.005)</td><td>-0.008*<br>(0.005)</td><td>-0.008*<br>(0.005)</td><td>-0.003<br>(0.005)</td><td>-0.003<br>(0.005)</td><td>-0.003<br>(0.005)</td><td>-0.003<br>(0.005)</td><td>-0.003<br>(0.005)</td></tr><tr><td>Non-Anonymous</td><td>0.011*<br>(0.006)</td><td>0.011*<br>(0.006)</td><td>0.011*<br>(0.006)</td><td>0.011*<br>(0.006)</td><td>0.011*<br>(0.006)</td><td>0.008<br>(0.007)</td><td>0.008<br>(0.007)</td><td>0.008<br>(0.007)</td><td>0.008<br>(0.007)</td><td>0.008<br>(0.007)</td></tr><tr><td>Small financial support (0/1)</td><td></td><td></td><td></td><td></td><td>0.013<br>(0.009)</td><td></td><td></td><td></td><td></td><td>-0.008<br>(0.008)</td></tr><tr><td>Large financial support (0/1)</td><td></td><td></td><td></td><td></td><td></td><td>-0.013<br>(0.011)</td><td></td><td></td><td></td><td>0.001<br>(0.011)</td></tr><tr><td>Help with production</td><td></td><td></td><td></td><td></td><td></td><td>0.002<br>(0.005)</td><td></td><td></td><td></td><td>0.008<br>(0.005)</td></tr><tr><td>Emotional support</td><td></td><td></td><td></td><td></td><td></td><td>0.008*<br>(0.004)</td><td></td><td></td><td></td><td>-0.002<br>(0.005)</td></tr><tr><td>Attend same church (0/1)</td><td></td><td></td><td></td><td></td><td></td><td>-0.014<br>(0.010)</td><td></td><td></td><td></td><td>0.011<br>(0.015)</td></tr><tr><td>Participant FE:</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>Y</td></tr><tr><td>Receiver FE:</td><td>N</td><td>N</td><td>Y</td><td>Y</td><td>Y</td><td>N</td><td>N</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>R<sup>2</sup></td><td>0.016</td><td>0.570</td><td>0.078</td><td>0.630</td><td>0.631</td><td>0.048</td><td>0.529</td><td>0.121</td><td>0.610</td><td>0.611</td></tr><tr><td>P-val Care + Care X Non-Anonymous=0</td><td>0.00</td><td>0.00</td><td>0.01</td><td>0.17</td><td>0.45</td><td>0.00</td><td>0.00</td><td>0.00</td><td>0.57</td><td>0.90</td></tr><tr><td>Observations</td><td>4702</td><td>4702</td><td>4702</td><td>4702</td><td>4680</td><td>3530</td><td>3530</td><td>3530</td><td>3530</td><td>3522</td></tr><tr><td>Mean DV</td><td>0.40</td><td>0.40</td><td>0.40</td><td>0.40</td><td>0.40</td><td>0.41</td><td>0.41</td><td>0.41</td><td>0.41</td><td>0.41</td></tr><tr><td>SD DV</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.26</td><td>0.26</td><td>0.26</td><td>0.26</td><td>0.26</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, excluding strangers. Standard errors clustered at the participant level in parentheses. *Child care* is the frequency of help with child care that the receiver provides to the participant, normalized to mean zero, standard deviation one. *Non-Anonymous* is an indicator variable taking value one for the non-anonymous giving condition.</footnote>
Turning to reciprocal motives, the positive and statistically significant (p-value < 0.10) coefficient for *Non-anonymous* (an indicator for the non-anonymous giving condition) in Table 1 suggests that the prospect of eliciting future cooperation is an important general motive for gift-giving. However, the sum of the coefficients on *Child care* and *Child care X Non-anonymous* ($β_1$ + $β_2$) is not statistically significantly different from zero in Columns 4 and 5, suggesting that inducing future reciprocity may not be the most important motivation in the relationship between allomaterial care and prosociality, and that strong reciprocal motives or gratitude for past help are perhaps more salient.

Overall, the results suggest that receiving help with child care makes mothers more generous towards those who provide more help. The point estimate suggests that a one standard deviation increase in help with child care (receiving help with care from a few times a month to a few times a week) is associated with a 1.5 percentage point increase in anonymous gift giving, a 3.84% increase at the mean.<fnref n="38" />

## 3.3 Help from non-relatives and altruism toward strangers

To examine the relationship between allomaterial care and altruism toward strangers, we turn to the relationship between help with child care that participants receive and their generosity toward strangers (i.e., random person in own village and random person in a distant village). Our experimental design specifies that strangers are not related to the participant, or even known to them, so there is no known history of reciprocal relationships.<fnref n="39" /> In practice, however, given the size of villages in our sample, a stranger in one's village could be a distant relative or a friend, and a non-anonymous gift may sow the seed of future reciprocation. Therefore, to capture different degrees of social distance, we elicit gift giving to strangers in both the same and distant villages, again both non-anonymously and anonymously. We consider non-anonymous giving to strangers as a proxy for weak altruism and anonymous giving to strangers as a proxy for strong altruism.

Looking at the raw experimental results, Figure 3 suggests that help with care from non-relatives is correlated with greater altruism toward strangers. Comparing the shares of the endowment sent to strangers between those who receive high (above median) vs. low (below median) help from non-relatives shows that participants who receive more help from non-relatives demonstrate greater prosociality toward strangers (uncontrolled t-tests shown in Appendix Table B7).

We test these relationships more rigorously in Table 2. We limit the sample to participants who have children and restrict the set of receivers to strangers. We estimate the

<footnote n="38">³⁸The mean share of the endowment in the anonymous gift giving condition is 0.39 for women.</footnote>

<footnote n="39">³⁹This explains why, by construction, specification (1) excludes strangers, since strangers cannot provide childcare.</footnote>
<figure><img src="image_4.png" /><figcaption>Figure 3: Dictator game giving to strangers and help with care from non-relatives</figcaption></figure>

Notes: N=374 mothers and 257 fathers. Bars represent the average share of the dictator game endowment given to strangers for mothers and fathers who receive a high amount of help with child care (above median) vs. a low amount of help (below median) from non-relatives (friends and neighbors). *p-value < 0.10, **p-value < 0.05, ***p-value < 0.01).

following equation, separately for mothers and fathers, at the level of a participant-receiver dyad, pooled over all treatment conditions (stranger in the same or distant village (s), and anonymous and non-anonymous giving (g)):

$$y_{ivsg} = \alpha + \sum_{k=1}^{3} \beta_{1k} \text{Care}_{ki} + \beta_{2} T_{sg} + \sum_{k=1}^{3} \beta_{3k} \text{Care}_{ki} * T_{sg} + X'_{i}\Gamma + \mu_{v} + \varepsilon_{ivsg} \quad (2)$$

where $y_{ivsg}$ is the share of the endowment given to stranger s from participant i in village v under giving condition g, and $Care_{ki}$ is the amount of help with child care provided to i by k, with k being: (i) the spouse, (ii) other relatives of the child, and (iii) non-relatives (friend, neighbor). In all specifications we interact the treatment conditions $T_{sg}$ (stranger in same vs. distant village; non-anonymous vs. anonymous) with each of the three child care variables to test different motives of altruism: (i) altruism strength (non-anonymous vs. anonymous), and (ii) social distance (same vs. distant village). Because the amount of help with child care does not vary across strangers for a given participant, our specifications cannot include participant fixed effects. We instead include village fixed effects $\mu_v$ that account for broad differences in prosociality or child care practices across villages, such as kinship, residence patterns or geography. Additionally, we include a wide range of participant-level controls in
$X_i$, such as age, proxies of the participant's presence of relatives in the village, which is the main predictor of help by relatives, proxies for social status, such as cognitive ability and wealth, which may influence both how much help participants can elicit and their generosity toward strangers, and number of children. For women, work in the gardens and participation in markets are significant predictors of how much allomaterial care they receive. These variables may also systematically correlate with prosocial preferences. We therefore control for the time participants spend working in their gardens and whether they sell goods in other villages. Moreover, given the substantial literature discussing how conflict exposure (see footnote 1 and Bauer et al. (2016) for a review) or religion (see, e.g. Norenzayan (2013)) may affect prosocial preferences, we also control for individual exposure to organized violence, as well as for religiosity. Finally, we account for the total amount of emotional, productive, and economic support provided to the participant from the individuals in their network, as well as the total number of these individuals who attend the same church congregation as the participant.

We first present uncontrolled regressions and then include individual covariates and in-
teraction terms in later specifications. Table 2 shows that help with child care from the
participant's spouse or relatives is not associated with altruism towards strangers. For fa-
thers, we observe no statistically significant or robust relationship between any form of
help with child care and generosity toward strangers. However, mothers who receive more
help from *non-relatives* (friends and neighbors) are systematically more generous toward
strangers. This result holds regardless of possible motives of altruism (weak or strong) or
social distance, as none of the interaction terms are statistically significant at p-value < 0.10.
It also holds controlling for a wide array of individual covariates, including how much social,
economic, and emotional support the participant receives, proxies for status and wealth,
and participation in markets. Again, child care help (from non-relatives) appears to matter
most for mothers: the coefficients associated with other forms of support are generally small
in magnitude, statistically indistinguishable from zero, and inconsistent in sign, with some
positive (number of church congregants) and some negative (total help with production).<fnref n="40" />

While some of the controls that are considered important correlates of prosociality, such
as participation in markets, are themselves correlated with allomaterial care from non-
relatives, the magnitude of the coefficient on care from non-relatives is either hardly affected

<footnote n="40">⁴⁰Benchmarking our effect size against the large literature on the relationship between conflict and prosocial behavior, the meta-analysis by Bauer et al. (2016) finds that the average effect of conflict on prosocial behavior in experiments is 0.17 SDs. By comparison, the estimated coefficient on *Care from: Non-relatives* for mothers in Table 2 is 0.027, which amounts to an effect size of 0.11 SDs. The identification in Table 2 is similar to most studies of conflict and relies on location fixed effects and conditional unconfoundedness. Our identification strategy in Table 1 relies on individual and recipient-type fixed effects, and is therefore more demanding. The estimated coefficient on *Child care* is smaller and equivalent to a 0.04 SD effect size.</footnote>
<table><caption>Table 2: Allom maternal care and dictator game giving to strangers</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th></tr><tr><th></th><th colspan="4">Mothers</th><th colspan="4">Fathers</th></tr></thead><tbody><tr><td>Care from: Spouse</td><td>-0.004<br>(0.008)</td><td>-0.002<br>(0.009)</td><td>-0.004<br>(0.010)</td><td>-0.002<br>(0.012)</td><td>0.005<br>(0.018)</td><td>0.000<br>(0.020)</td><td>0.019<br>(0.021)</td><td>0.013<br>(0.021)</td></tr><tr><td>Care from: Relatives of child</td><td>-0.014<br>(0.010)</td><td>-0.013<br>(0.014)</td><td>-0.011<br>(0.014)</td><td>-0.009<br>(0.017)</td><td>0.021*<br>(0.012)</td><td>0.022<br>(0.017)</td><td>0.013<br>(0.016)</td><td>0.014<br>(0.019)</td></tr><tr><td>Care from: Non-relatives</td><td>0.024**<br>(0.011)</td><td>0.027**<br>(0.011)</td><td>0.024*<br>(0.013)</td><td>0.027*<br>(0.013)</td><td>0.013<br>(0.015)</td><td>0.019<br>(0.016)</td><td>0.014<br>(0.019)</td><td>0.020<br>(0.020)</td></tr><tr><td>Same village × Care from: Spouse</td><td></td><td></td><td>0.003<br>(0.010)</td><td>0.003<br>(0.010)</td><td></td><td></td><td>-0.024<br>(0.019)</td><td>-0.023<br>(0.019)</td></tr><tr><td>Same village × Care from: Relatives of child</td><td></td><td></td><td>0.009<br>(0.009)</td><td>0.008<br>(0.009)</td><td></td><td></td><td>0.003<br>(0.015)</td><td>0.005<br>(0.015)</td></tr><tr><td>Same village × Care from: Non-relatives</td><td></td><td></td><td>-0.005<br>(0.008)</td><td>-0.005<br>(0.008)</td><td></td><td></td><td>-0.004<br>(0.016)</td><td>-0.006<br>(0.015)</td></tr><tr><td>Non-Anonymous × Care from: Spouse</td><td></td><td></td><td>-0.003<br>(0.009)</td><td>-0.003<br>(0.009)</td><td></td><td></td><td>-0.003<br>(0.016)</td><td>-0.003<br>(0.016)</td></tr><tr><td>Non-Anonymous × Care from: Relatives of child</td><td></td><td></td><td>-0.016<br>(0.010)</td><td>-0.016<br>(0.010)</td><td></td><td></td><td>0.011<br>(0.012)</td><td>0.011<br>(0.013)</td></tr><tr><td>Non-Anonymous × Care from: Non-relatives</td><td></td><td></td><td>0.005<br>(0.008)</td><td>0.005<br>(0.008)</td><td></td><td></td><td>0.003<br>(0.014)</td><td>0.003<br>(0.014)</td></tr><tr><td>Same village</td><td>0.030**<br>(0.013)</td><td>0.030**<br>(0.013)</td><td>0.033**<br>(0.013)</td><td>0.032**<br>(0.013)</td><td>0.034***<br>(0.011)</td><td>0.034***<br>(0.011)</td><td>0.045***<br>(0.016)</td><td>0.044**<br>(0.016)</td></tr><tr><td>Non-Anonymous</td><td>0.013<br>(0.010)</td><td>0.013<br>(0.010)</td><td>0.010<br>(0.012)</td><td>0.010<br>(0.012)</td><td>0.019<br>(0.015)</td><td>0.019<br>(0.015)</td><td>0.020<br>(0.019)</td><td>0.020<br>(0.019)</td></tr><tr><td>Emotional support</td><td></td><td></td><td>-0.000<br>(0.013)</td><td>-0.000<br>(0.013)</td><td></td><td>-0.031**<br>(0.015)</td><td></td><td>-0.031**<br>(0.015)</td></tr><tr><td>Small financial support</td><td></td><td></td><td>0.004<br>(0.012)</td><td>0.004<br>(0.012)</td><td></td><td>0.003<br>(0.015)</td><td></td><td>0.003<br>(0.015)</td></tr><tr><td>Large financial support</td><td></td><td></td><td>-0.010<br>(0.010)</td><td>-0.010<br>(0.010)</td><td></td><td>-0.013<br>(0.014)</td><td></td><td>-0.013<br>(0.014)</td></tr><tr><td>Production support</td><td></td><td></td><td>-0.021<br>(0.016)</td><td>-0.021<br>(0.016)</td><td></td><td>0.023<br>(0.018)</td><td></td><td>0.023<br>(0.018)</td></tr><tr><td>Church congregants</td><td></td><td></td><td>0.011<br>(0.013)</td><td>0.011<br>(0.013)</td><td></td><td>0.015<br>(0.014)</td><td></td><td>0.014<br>(0.014)</td></tr><tr><td>Additional controls:</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Villages</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td></tr><tr><td>Observations</td><td>1444</td><td>1444</td><td>1444</td><td>1444</td><td>968</td><td>968</td><td>968</td><td>968</td></tr><tr><td>R<sup>2</sup></td><td>0.247</td><td>0.276</td><td>0.249</td><td>0.277</td><td>0.218</td><td>0.262</td><td>0.220</td><td>0.264</td></tr><tr><td>δ Care from: Non-relatives</td><td></td><td>1.87</td><td></td><td>-2.74</td><td></td><td>3.63</td><td></td><td>-2.76</td></tr><tr><td>Mean DV</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.28</td><td>0.28</td><td>0.28</td><td>0.28</td></tr><tr><td>SD DV</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.24</td><td>0.24</td><td>0.24</td><td>0.24</td></tr></tbody></table>

or becomes larger when we include the full range of individual-level covariates. Coefficients from a test for selection on unobservables (Oster, 2019) suggest that the influence of omitted variables would need to be roughly twice as large as the influence of all included controls to explain away the coefficient associated with allom maternal care from non-relatives (δ displayed

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, restricted to strangers, only. All estimates include village fixed effects. Additional controls include log of participant's age, cognitive ability, number of children, number of relatives living in the village, ownership of consumer durables, whether the participant ever witnessed inter-village violence, and religiosity. Care variables represent the amount of help with child care that each group provides to the participant standardized to mean zero, standard deviation one. Non-Anonymous is an indicator variable taking value one for the non-anonymous giving condition. Support variables represent the total amount of support, for each type of support as described in the main text, received from the various individuals in a participant's network, normalized to mean zero, standard deviation one. Standard errors clustered at the village level in parentheses. The coefficients δ are calculated using the psacalc function in Stata assuming an R-max = 1.3 * R<sup>2</sup> and represent the proportional degree of selection on unobservables needed to overturn the estimated effects. Missing observations imputed to the sample mean for control variables and all estimates include indicator variables for missing observations.</footnote>
at the bottom of Table 2).<sup>41</sup> In terms of magnitude, the results suggest that for mothers, a standard deviation increase in help with child care from non-relatives corresponds to a 0.025 percentage point increase in the share sent to strangers, which corresponds to a 9.26% increase at the mean.<sup>42</sup> Table B8 shows that our results are unchanged if we include an interaction between the same village and reciprocity treatments.<sup>43</sup>

Table B9 in the Appendix displays the coefficients associated with each individual control. For mothers, time spent in the gardens is significantly associated with gift-giving to strangers. The coefficients associated with market participation or with religiosity are not significantly associated with gift giving to strangers. The coefficient associated with witnessing organized violence is negative, and only statistically significant for mothers at the 10% level. The negative sign is consistent with the literature on parochialism and previous results by Cassar et al. (2013) and Rohner et al. (2013), given that we elicit giving specifically to *strangers*. For fathers, the only significant coefficients are those associated with our wealth proxy, performance on a cognitive task, and emotional support. They are all negative, suggesting that men with higher status and more emotional support in their village are less generous toward strangers. We also find that, as expected due to the closer social distance, the coefficients on *Same Village* indicate that gift giving to strangers in the same village is higher than to strangers in a distant village, both for mothers and fathers.

## 3.4 Group-level evidence on non-parents

Finally, to shed some light on potential group-level effects, we limit our analysis to participants who do not have children, and thus do not directly benefit from the provision of child care. We correlate the share of the dictator game endowment that these non-parents give to strangers with the average amount of child care help that parents in their village receive. Appendix Tables B10 and B11 show a positive and significant relationship (p-value < 0.05) between impersonal prosociality and village-level help with child care, which is robust to the inclusion of a large number of individual covariates as controls, including age, cognitive ability, number of relatives living in the village, wealth, religiosity, and personal

<footnote n="41"><sup>41</sup>Negative coefficients result from the coefficient of interest becoming larger when including additional covariates, suggesting that if anything, the inclusion of unobserved variables would make the coefficient larger.</footnote>

<footnote n="42"><sup>42</sup>Our findings of giving to strangers (see Table B6) between 25% (anonymously to distant village by women) and 32% of the endowment (non-anonymously to same village by men) align closely with the average results of Henrich et al. (2005), which reports an average giving of 28% across all societies, with significant variation depending on the society, ranging from as low as 20% (among the Hadza in Tanzania) to as high as 58% (among the Lamalera whale hunters in Indonesia).</footnote>

<footnote n="43"><sup>43</sup>The results in Table B8 also illustrate that people do understand the distinction between anonymous and non-anonymous payments: the estimate associated with the interaction between the non-anonymous gift and the same village treatment is positive and statistically significant, and large in magnitude (+12.5% of the average amount sent in the DG) for men. For women, it is positive but not significant.</footnote>
exposure to conflict, as well as to the inclusion of an interaction between the same village and non-anonymous treatments. These results suggest that altruism can be sustained by generalized norms of prosociality that also influence the behavior of those who do not directly benefit from allomaternal care. Moreover, consistent with our individual level results for mothers, the statistically significant interaction term in Columns 5 and 6 indicates that this relationship is driven by women.

The results thus far show that help with child care is associated with greater prosociality, and that help from non-relatives specifically is associated with heightened altruism. Overall, this suggests a link between allomaternal care and prosociality that goes beyond simple reciprocal relationships and generalizes to impersonal interactions. This evidence is consistent with the cross-cultural evidence discussed in the Introduction and provides support for the hypothesis that the social organization for child rearing may be a crucial element for cooperation. Our findings suggest that the capacity for generalized prosociality may be linked to cooperation with non-relatives over child care.

# 4 Allomaternal care and benefits to children

We now investigate whether allomaternal care is associated with socio-cognitive benefits to children. We focus on language, a unique human social characteristic. We calibrate measures of child socio-cognitive development based on the number of child vocalizations estimated from child-centered long-form recordings collected from 197 children using a wearable recording device (Lavechin et al., 2021). We analyze recordings using a multilingually-trained, neural network that outperforms other software alternatives (Lavechin et al., 2020).

We regress child vocalization counts on the amount of care that the child receives from various people, including their mother, father, other relatives (grandparents, aunts and uncles), and non-relatives (friends and neighbors).44 We include village fixed effects to account for broad geographic, cultural, and linguistic differences across villages that could influence child outcomes. We control for child-characteristics that could influence child socio-cognitive development and correlate with the amount of care that the child receives from different caregivers, such as age, gender, BMI, total number of children in the household, and whether the mother's spouse is the child's biological father. We also control for mother-level characteristics that influence child cognitive and non-cognitive development directly,45 such as mother's age, cognitive ability, and wealth, or indirectly through her time constraints, socialization environment, and mental well-being,46 such as the total amount of social, emotional, pro-

<footnote n="44">⁴⁴More information on the specification is included in Section C of the Appendix.</footnote>

<footnote n="45">⁴⁵See, e.g., Kosse et al. (2020); Falk et al. (2021).</footnote>

<footnote n="46">⁴⁶See, e.g., Baranov et al. (2020).</footnote>
ductive, and economic support she receives from all individuals in her network, time spent
in gardens and market participation (an important predictor of care by non-relatives), the
presence of relatives in the village (an important predictor of care by relatives), religiosity,
and conflict exposure.

These controls may play an important role in our estimation. Mothers’ time spent in gardens and market participation may reduce the time spent with her children and increase the amount of care given by non-relatives. We thus expect the inclusion of these controls to improve the precision of our estimates. Yet, there is also a possibility that some of these controls are endogenous to child socio-cognitive outcomes and allom maternal care. For example, mothers may participate less in markets if finding a friend or neighbor willing to take care of a child is more difficult for a children with low socio-cognitive skills. To address this possibility, we systematically present the results of specifications that include only basic controls (child age and gender, mother age), as well as the full set of controls.

The results displayed in Table 3 show that care from non-relatives is a robust and con-
sistent predictor of higher child vocalizations. Care from any other caregiver does not con-
sistently correlate with our measure of child socio-cognitive development. Care from the
mother is positively associated with vocalizations, care by the father negatively, and care by
other relatives of the child inconsistent in sign; but none of the coefficients are statistically
distinguishable from zero.

Estimates displayed in Column 4 of Panel A (with minimal controls for child age and gender and mother age) suggest that receiving care by non-relatives on at least a weekly basis is associated with more vocalizations. Parsimoniously controlling for care by different caregivers as we do in Columns 1 to 4 may mask systematic correlations in care by different caregivers. To address this, Column 5 controls for all inputs by different caregivers together. The coefficient associated with care by non-relatives is barely affected, and if anything, increases slightly in magnitude, suggesting that care by non-relatives does not, in our context, fully substitute for care by other caregivers. The coefficient suggests 22.76 more vocalizations per hour (an 11% increase from the mean) with weekly or more frequent care from non-relatives.

Child care provided by non-relatives may also capture other dimensions of maternal support, such as emotional or social support. In the specifications displayed in Panel B, we control for all other dimensions of maternal support, as well as the other mother-level controls discussed above. In particular, we control for time spent in gardens and market participation, which for mothers are associated with child care help from non-relatives. The coefficients for each of the controls are displayed in Appendix Table B12.

As expected, controlling for the extended set of controls improves the precision of the
<table><caption>Table 3: Allomaterial care and child vocalizations</caption><thead><tr><th></th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th></tr></thead><tbody><tr><td colspan="6"><strong>Panel A: Vocalizations per hour – Basic controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-0.791<br>(5.587)</td><td></td><td></td><td>-0.494<br>(5.973)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-15.650<br>(10.577)</td><td></td><td>-17.220<br>(10.733)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-2.508<br>(18.035)</td><td>-4.841<br>(19.142)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>20.401*<br>(11.920)</td><td>22.756*<br>(11.869)</td></tr><tr><td>R<sup>2</sup></td><td>0.407</td><td>0.413</td><td>0.407</td><td>0.413</td><td>0.420</td></tr><tr><td colspan="6"><strong>Panel B: Vocalizations per hour – Extended controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>1.599<br>(6.133)</td><td></td><td></td><td>2.578<br>(6.156)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-13.767<br>(10.403)</td><td></td><td>-14.264<br>(10.307)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-1.236<br>(17.902)</td><td>-3.072<br>(18.655)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>31.008**<br>(13.208)</td><td>31.174**<br>(13.175)</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>378</td><td>378</td><td>378</td><td>378</td><td>378</td></tr><tr><td>R<sup>2</sup></td><td>0.465</td><td>0.468</td><td>0.465</td><td>0.476</td><td>0.480</td></tr><tr><td>Mean DV</td><td>206.67</td><td>206.67</td><td>206.67</td><td>206.67</td><td>206.67</td></tr><tr><td>SD DV</td><td>80.87</td><td>80.87</td><td>80.87</td><td>80.87</td><td>80.87</td></tr></tbody></table>

estimate associated with care by non-relatives. The coefficient suggests that receiving care by non-relatives on at least a weekly basis is associated with 31 more vocalizations per hour, which amounts to 15% of the mean, (p-value < 0.05). In Appendix Table B13, we include an additional control for the mother's stress hormone, noting that the sample size is reduced to only those children for whom a child-mother hair sample was collected (102 children). The estimates are robust to controlling for mother stress and confirm that care by non-relatives

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a child recording. Care variables are indicators for whether the child receives care at the frequency indicated. All estimates include village fixed effects, and control the child's ln(age), gender, and mother's ln(age). Panel B includes the following additional controls: child BMI, whether the mother's spouse is the biological father of the child, total number of children in the household, and the following controls for the mother: cognitive ability, number of consumer durables owned, amount of time spent working in the gardens, amount of time spent selling goods in another village, whether she has witnessed inter-village violence, religiosity, and the amount of various forms of support (i.e., small and large financial, help with production, emotional support, and attend the same church) that she receives from all individuals in her network. Support variables and time working in gardens and selling goods normalized to mean zero, standard deviation one. Standard errors in parentheses, clustered by child. Missing observations imputed for control variables and all estimates include indicator variables for missing observations of control variables. All estimates weighted by the duration of the recording. Table B12 displays the full controls of Panel B.</footnote>
is the only type of care that is positively associated with higher vocalizations. In addition, mother stress is, as could be expected, negatively associated with child vocalizations.

The only other robust predictors of child vocalizations are the amount of large financial support the mother receives (negative correlation, p-value < 0.05) and mother's participation in markets (positive correlation, p-value < 0.10). The result for mother's market participation suggests that such behavior may reflect mothers' non-cognitive skills, which may be partly inherited and predictive of children's socio-cognitive development. Although we observe a weak negative correlation between performance on the cognitive task and market participation (-0.17), the correlation between market participation and emotional support is positive (0.24), suggesting that market participation may indeed partly reflect social skills.<fnref n="47" />

A potential limitation of automated long-form recording data is the possibility that cries, and hence child distress, may be categorized as vocalizations.<fnref n="48" /> We address this possibility in two ways. First, we observe that given the magnitude of our results and the low average proportion of crying in vocalizations, it is unlikely that our results can be entirely explained by stress. The average proportion of crying in vocalizations coded by lab scientists in a random subset of our data was 3.20%; applying this to the mean vocalization suggests an estimate of 6.58 average crying vocalizations per hour. The coefficient associated with weekly or more frequent care by non-relatives hovers around 20-30 additional vocalizations, which would represent a 300-450% increase in crying if the effect were entirely due to distress, which seems implausibly large. Second, to provide a more direct measure of distress, we collected measures of child emotional wellbeing from hormonal biomarkers for cortisol and cortisone in hair samples of 102 mother-child pairs. The rationale for collecting this data is that unmet children's needs, excessive crying, and distress under the care of others would translate into higher levels of stress.

The results displayed in Appendix Table B17 show that care from non-relatives is associated with lower levels of stress hormones, cortisone and cortisol, in children.<fnref n="49" /> The coefficient remains negative, but loses significance, when the full set of extended controls is included.

<footnote n="47">⁴⁷The correlation between performance on the cognitive task and emotional support is itself negative and small in magnitude (-0.10).</footnote>

<footnote n="48">⁴⁸We have already commented on the accuracy of VTC to measure child vocalizations. We further provide evidence in Appendix Tables B14 and B15 that these results do not reflect more vocalizations by adults, or more background noise. We replicate the analysis in Table 3 but for adult female and adult male vocalizations as dependent variables, instead of child vocalizations. We find no relationship between care by non-relatives and adult female or male vocalizations. We also check in Appendix Table B16 that our main results in Table 3 are robust to winsorizing our sample, excluding the top and bottom fifth percentiles in recording duration.</footnote>

<footnote n="49">⁴⁹The results also show that mother stress is, as expected, positively correlated with child stress. More information on the empirical specifications used to generate these results is included in Section C of the Appendix.</footnote>
The result that care by non-relatives is, if anything, negatively associated with child stress suggests that our vocalization result is unlikely to be driven by cries. Given that higher levels of cortisol and cortisone are associated with impaired brain development in children (Lupien et al., 1998, 2009) and, for adults in laboratory settings, increased cortisol is associated with lower prosociality (Haushofer et al., 2023), the result that care by non-relatives is negatively associated with child stress suggests potential socio-emotional benefits that go beyond the socio-cognitive benefits that we document.

# 5 Allom maternal care and growth

The literature in evolutionary biology and anthropology characterizes allom maternal care as critical for human demographic success, as allom maternal care enables women to have more children (Hrdy, 1999; Kramer, 2010). Population growth is also the key indicator of economic development in preindustrial societies, such as the ones studied in the SCCS and in our Solomon Islands sample (Ashraf and Galor, 2011). Following Enke (2019), we use the SCCS variable on population density in seven ordered categories (variable v64 “Population Density” from less than 1 person per 5 sq. mile to over 500 persons per sq. mile). In our Solomon Islands sample, we use the (log) of population as an outcome. As in Enke (2019), we also consider the following additional proxies of economic and political development, available in the SCCS: (i) the complexity of local settlements in eight ordered categories (variable v705 “Settlement type” from 1: “Fully migratory or nomadic bands” to 8: “Complex settlements surrounded by homes”), and (ii) the mean size of communities in eight ordered categories (variable v235 “Mean Size of Local Communities” from 1: “fewer than 50” to 8: “one or more cities of more than 50,000”). In our field sample, we use wealth (measured by an asset scale of durable assets) as a direct proxy of economic development.

Table 4 summarizes the relationships between allom maternal care and these proxies for local
development. Allom maternal care is positively and consistently correlated with population
density, complexity of local settlements, and the size of communities in the SCCS, and with
population and wealth in our Solomon Islands sample. In summary, evidence suggests that
allom maternal care is associated with demographic success and economic development.
<table><caption>Table 4: Allomaterial care and Growth</caption><thead><tr><th></th><th>Pop.<br>Density<br>(1)</th><th>Complex.<br>Settle.<br>(2)</th><th>Size<br>Comm.<br>(3)</th><th>Vill<br>Pop<br>(4)</th><th>Consum.<br>Durables<br>(5)</th></tr></thead><tbody><tr><td>Allomaterial care (SCCS)</td><td>0.119**<br>(0.054)</td><td>0.230**<br>(0.103)</td><td>0.198**<br>(0.096)</td><td></td><td></td></tr><tr><td>Care from: Non-relatives (SI)</td><td></td><td></td><td></td><td>0.290*<br>(0.145)</td><td>0.240*<br>(0.121)</td></tr><tr><td>Fixed Effects:</td><td>Y</td><td>Y</td><td>Y</td><td>NA</td><td>NA</td></tr><tr><td>Controls:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>157</td><td>78</td><td>128</td><td>43</td><td>44</td></tr><tr><td>R<sup>2</sup></td><td>0.355</td><td>0.170</td><td>0.318</td><td>0.109</td><td>0.159</td></tr></tbody></table>

# 6 Discussion and Conclusion

This work provides novel empirical evidence suggestive of a positive relationship between allomaterial care and prosociality. In particular, the association of care by non-relatives with giving to strangers has important implications for impersonal prosociality (altruism). Furthermore, using hormonal data and child vocalizations analyzed through a multilingually-trained neural network, we document socio-cognitive benefits that allomaterial care may bestow on children. Lastly, the correlation between allomaterial care and population measures at the village level and across societies suggests a positive association with economic growth.

Our analysis, based on a combination of experimental and survey data, calibrates the

<footnote>* p< 0.10, ** p<0.05, *** p < 0.01. Historical ethnic group-level OLS estimates in the SCCS in Columns 1 to 3; village-level OLS estimates in our Solomon Islands (SI) samples in Columns 4 and 5. The dependent variables in columns (1)–(3) are: population density, the complexity of settlements, and community size in the SCCS (see definitions in text and in Appendix D1). Allomaterial care - SCCS captures non-maternal relationships in infancy from the SCCS (variable v51) in 5 ordered categories from “Almost exclusively mother” to “Mother minor but significant” (see more detail in Appendix A). Geographic controls include log rainfall, log average annual temperature, latitude, longitude, altitude, number of dry months, number of frost months, and date at which the society is observed. The number of observations varies because of missing observations in the SCCS. The dependent variable in column (4) is the (log) of population in a village in our field sample. The dependent variable in column (5) is individual ownership of consumer durables. The independent variable in Columns 4 and 5 (Care from: Non-relatives (SI)) is the average amount of help with child care that parents receive from non-relatives in the village. Geographic controls include latitude, longitude. All displayed coefficients are standardized. Robust standard errors in parentheses.</footnote>
relationship between various dimensions of help and prosociality, and produces results consistent with the hypothesis that help with child care has a primal role in predicting reciprocity and altruism. We find evidence of heightened prosociality not just toward relatives and other network members but also toward strangers, suggesting an important, less studied foundation for the development of impersonal prosociality. Given the relevance of care by non-relatives in our findings, our analysis suggests a new mechanism that can help to explain the negative relationship between the strength of family and social ties and cooperative behavior, whose negative consequences for economic and political development have been established by several studies (Banfield, 1958; Alesina and Giuliano, 2011, 2014; Alesina et al., 2015; Enke, 2019; Bahrami-Rad et al., 2022; Schulz, 2022).

Our framework, focusing on the need to elicit and maintain cooperation for the purpose of child rearing, and our findings, showing enhanced prosociality with greater allomaternal care, can be seen as complementary to the more widespread hypothesis in the literature which roots prosociality in intergroup conflict. Although the role of gender has been somewhat overlooked in asexual models of representative agents (Choi and Bowles, 2007; Bowles, 2008), other strands of the social sciences literature, with few exceptions (Cassar et al., 2023), have pointed to an especially male psychology to explain the emergence of cooperation, the so-called “male warrior hypothesis” (Vugt et al., 2007; Yuki and Yokota, 2009; McDonald et al., 2012). By contrast, our results are primarily predictive of women’s prosociality.

A potential explanation for why our results hold more strongly for women lies in gender differences in network formation and use. Despite similarities across genders in who helps with child care, with both parents receiving similar help from genetic relatives of the child, there are also important differences. In particular, mothers rely much more on non-relatives to take care of children than fathers. This more acute need for mothers to elicit and maintain networks of unrelated carergivers may have important implications for the economic returns to networks and how these returns differ across genders. The economic literature on social networks has described how women's social networks are, compared with men's, more stable, smaller, composed of a greater proportion of strong relative to weak links, and less responsive to information about the likely monetary returns to a link (see, e.g., Yang et al., 2019; Friebel et al., 2021). In economic contexts like job search, more weak links are often more useful: acquaintances' greater ability to provide novel information outweighs their lesser motivation to provide support and help (see Granovetter (1973) and Beaman et al. (2018) for empirical evidence). Conversely, in contexts like child care, the benefits of stronger links (with greater motivation to cooperate, commitment, and knowledge about trustworthiness) matter more than their ability to provide information.

The characteristics of child care networks that we describe in this paper are also directly
tied to female labor. Even in the context of small-scale horticultural societies that we study, care by non-relatives is particularly important for women who work more in their gardens or spend more time selling goods in markets outside of their village. Fostering these networks may thus not only matter for prosociality, but also free women's ability to work outside the home.

Finally, our work suggests a new mechanism and interpretation of the findings that, compared with exclusive care by parents, the provision of child care by others is associated with long-term advantages in cognition, educational achievement, non-cognitive skills, earnings, and social preferences (Cunha and Heckman, 2007; Heckman, 2013; Cappelen et al., 2020; Attanasio et al., 2022a,b; Bjorvatn et al., 2022). We document that care by unrelated individuals is associated with language development in children, a crucial socio-cognitive skill for cooperation and communication. Our findings could be relevant for the design of early childhood and parenting interventions, which should consider and potentially leverage networks of unrelated acquaintances to provide regular care to children without necessarily substituting for maternal care, such as mothers' groups.

Overall, our findings about the importance of caregiving networks, over other social, emotional, productive and risk-sharing networks, as a potential foundation of prosociality and determinant of child human capital suggest that these networks are a promising new avenue to promote a number of policy interventions targeting women and children, in particular early childhood education, female empowerment, and female labor force participation programs.
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# Online Appendix:

It Makes a Village: Child Care and Prosociality

Cassar, Cristia, Grosjean, and Walker

<table><tr><td>A Evidence from the Standard Cross-Cultural Sample</td><td>2</td></tr><tr><td>B Appendix Tables</td><td>6</td></tr><tr><td>C Empirical specifications for summary figures and child-level regressions</td><td>23</td></tr><tr><td>D Data Appendix</td><td>25</td></tr><tr><td>E Experimental Instructions</td><td>29</td></tr></table>
# A Evidence from the Standard Cross-Cultural Sample

## A.1 Dataset and variable description

The Standard Cross-Cultural Sample (SCCS; Murdock and White (1969)) contains detailed information on 186 cultural societies across the world that were originally selected from a list of 1,265 societies in the Ethnographic Atlas (EA). The goal of the SCCS is to represent the cultural diversity of human societies, which range from now extinct civilizations to contemporary hunter-gatherers. These societies are considered largely independent of one another and arguably representative of mutually distinct cultures (Murdock and White, 1969).

Information on child care practices is available for a subset of the societies in the SCCS. To match the age range of children included in our sample, we focus on the question on the role of non-maternal relations in infancy (hereafter, allomaterial care) (v51, N=162). Answers are coded from 1 to 6, with 1 capturing care “almost exclusively by mother” (in 5 societies: Azande, Callinago, Fon, Konso, and Kwoma), 5 describing societies in which the care by mothers is “minor but significant” (in 2 societies: Alorese and Irish) and 6 capturing mothers having a minimal role “except nursing” (in 1 society: Ancient Rome, a single outlier that we exclude from our analysis, although our results are insensitive to including it). The mean value of this allomaterial care variable is 2.52 (s.d. 0.72).

Figure A1 maps the distribution of allomaterial care practices across the world. Allomaterial care in infancy is most prevalent in the Insular Pacific region (mean of v51: 2.66, but not statistically significantly different from the rest of the world (P-value difference in means: 0.27) and lowest in the Americas (2.43).

The SCCS also includes information on trust (v335, N=138), which we leverage as a proxy for prosocial norms. This variable is originally coded in Barry et al. (1976) and “refers to confidence in social relationships, especially toward community members outside the family, e.g., children are welcome in any home in the village, possessions are left unguarded” (Barry et al., 1976, p.95). It is coded on a scale of 0 (“No Inculcation, or Opposite Trait”, coded in only one society, the Kwoma) to 10 (“Extremely Strong Inculcation”, coded in only one society, the Mbuti). It has a mean of 5.15, and a standard deviation of 2.23, and the mode of the distribution is 5 (“Moderately Strong Inculcation”). The societies scoring highest on this variable are the Mbuti (v335 = 10), the Tikopia, Havasupai, and King Bushmen (for whom v335 = 9); and the lowest are the Kwoma (v335 = 0), which, incidentally, is also among the societies with the least allomaterial care. This variable is strongly correlated with inculcation of honesty (variable v336 in SCCS, raw correlation: 0.45), which “refers to desire and strong approval for truthfulness under all circumstances” in the society (Barry et al., 1976, p.95). Consistent with a recent literature on the negative relationship between witchcraft and prosociality in a society (Quinlan and Quinlan, 2007; Le Rossignol et al., 2023), we also verify a negative and statistically significant correlation (raw correlation: -0.28) between our measure of prosociality and presence of witchcraft in the subset of 97 societies for which both information on trust inculcation and on witchcraft are available (question v656 Theories of Witchcraft, with answers: 1. Absence of such a cause; 2. Minor or relatively unimportant cause; 3. An important auxiliary cause; 4. Predominant cause recognized by the society).
<figure><img src="image_5.png" /><figcaption>Figure A1: Allomaterial care and trust in the Standard Cross-Cultural Sample (SCCS)</figcaption></figure>

Notes: Allomaterial care comes from question v51 in the SCCS. Trust comes from question v335 in the SCCS: importance of inculcation of trust in childhood. The Figure maps the quantiles of the distribution of these variables across the world. Source: SSCS (Murdock and White, 1969).

## A.2 Analysis underlying Figure 1

Figure A1 overlays the quantiles of this variable with the prevalence of allomaterial care across the world. Inculcation of trust is most important in East Eurasia (mean: 6.16), followed by Africa (5.5) and the Insular Pacific (5.35), and lowest in the Circum-Mediterranean region (mean: 3.88).

Figure 1 in Introduction shows the correlation between prosocial orientation and the prevalence of allomaterial care in the SCCS. It plots the conditional expectation function of societal trust orientation conditional on allomaterial care provision in infancy, controlling for region fixed effects (v200 in the SCCS: Africa, Circum-Mediterranean, East Eurasia, Insular Pacific, North America, South America), log mean yearly average rainfall (v1913), log mean annual temperature (v186), latitude and longitude, which could all influence both child care arrangements and social preferences. To address potential criticisms of the SCCS related to the underlying variation in the time at which each society was observed and in the timing of publication of the different ethnographies and documents used to assemble the SCCS, we control for the date at which the society was observed (variable *focyear*), and the publication date of the study dealing with a given society (v802).<fnref n="50" /> We additionally

<footnote n="50">⁵⁰For missing values of *v802*, we impute 0 values and include an indicator variable for missing observations</footnote>
control for the presence of a belief in moralizing gods who intervene in human affairs, which has been discussed in the literature as an important determinant of trust and cooperation (Lang et al., 2019) (variable v238, High Gods, 1= Absent or not reported, 2= Present but not active in human affair, 3= Present and active in human affairs, 4= Present, active, and specifically supporting morality).

In other words, we estimate the following multivariate OLS regressions at the level of a society (s) in the SCCS:

$$Trust_{sr} = \alpha_1 + X'_{sr}\Gamma + \delta_r + \varepsilon_{sr} \quad (3)$$

$$Allocare_{sr} = \alpha_2 + X'_{sr}\Gamma_2 + \delta_{2r} + \varepsilon_{2sr} \quad (4)$$

where Trust$_{sr}$ is the average trust orientation of society s in region r, and Allocare$_{sr}$ measures alomaterial care in infancy in society s in region r. X$_{sr}$ is a vector of society-level characteristics that could be correlated both with child care practices and with societal trust orientation, and includes climatic conditions, latitude, longitude, the date at which each society was observed, and the presence of a belief in moralizing gods; and δ$_{r}$ is a set of regional area fixed effects.

The binscatter in Figure 1 plots the mean estimated residuals ε$_{1sr}$ against the mean estimated residuals ε$_{2sr}$, averaged in equal-sized bins. The Figure also displays the best linear fit line, constructed from an OLS regression of the y-residuals ε$_{1sr}$ on the x-residuals ε$_{2sr}$. The slope of the fit line matches the coefficient of the following multivariate OLS regression:

$$Trust_{sr} = \alpha + \beta Allocare_{sr} + X'_{sr}\Gamma + \delta_r + \varepsilon_{sr} \quad (5)$$

of societal trust orientation on allomaterial care, controlling for the same set of controls and fixed effects as in equations (3) and (4). Throughout, we cluster standard errors at the language family level.

The corresponding regression results displayed in Table A1 confirm a strong, positive, and robust correlation between allomaterial care and trust across societies.

Controlling for region fixed effects δ$_{r}$, geographic controls, presence of a belief in moralizing gods, and dates of ethnographies, the point estimates suggests that a one unit increase along the allomaterial care scale is associated with a 0.77 increase in trust, which corresponds to a 14.56% increase at the mean. Standardized estimates suggest that a one standard deviation increase in allomaterial care is associated with a 0.25 standard deviation increase in societal trust. The coefficient is statistically significant at the 3% level. These estimates, which correspond to the estimates obtained from estimating equation (5), are displayed in Column 3 of Table A1. The uncontrolled estimate, displayed in Column 1 is close in magnitude and statistically significant at the 1.4% level.

<footnote>as an additional regressor in X$_{sr}$.</footnote>
<table><caption>Table A1: Societal trust in the SCCS and Allomaterial care</caption><thead><tr><th rowspan="2"></th><th colspan="3">Societal Trust Orientation in the SCCS</th></tr><tr><th>(1)</th><th>(2)</th><th>(3)</th></tr></thead><tbody><tr><td>Allomaterial care</td><td>0.703**<br>(0.275)</td><td>0.612**<br>(0.273)</td><td>0.766**<br>(0.334)</td></tr><tr><td>Regional Area Fixed Effects</td><td></td><td>✓</td><td>✓</td></tr><tr><td>Geographic Controls</td><td></td><td>✓</td><td>✓</td></tr><tr><td>Community Size</td><td></td><td>✓</td><td>✓</td></tr><tr><td>Dates Pub.</td><td></td><td>✓</td><td>✓</td></tr><tr><td>Religion</td><td></td><td></td><td>✓</td></tr><tr><td>R-squared</td><td>0.05</td><td>0.16</td><td>0.19</td></tr><tr><td>Observations</td><td>121</td><td>121</td><td>109</td></tr><tr><td>Mean DepVar</td><td>5.29</td><td>5.29</td><td>5.29</td></tr><tr><td>Sd DepVar</td><td>2.25</td><td>2.25</td><td>2.27</td></tr></tbody></table>

Notes: Historical ethnic group-level OLS estimates in the SCCS. The dependent variable is the importance of inculcation of trust in childhood in the SCCS. Regional are fixed effects are from question v200 Geographic controls include log rainfall, log average annual temperature, latitude, longitude, and date at which the society is observed. All displayed coefficients are standardized. Robust standard errors (*** p<0.01, ** p<0.05, * p<0.10).
# B Appendix Tables

<table><caption>Table B1: Summary statistics</caption><thead><tr><th></th><th>N</th><th>Mean</th><th>SD</th><th>Min</th><th>Max</th></tr></thead><tbody><tr><td colspan="6"><em>Participant information</em></td></tr><tr><td>Female</td><td>820</td><td>0.52</td><td>0.50</td><td>0.00</td><td>1.00</td></tr><tr><td>Age</td><td>817</td><td>30.85</td><td>7.83</td><td>16.00</td><td>54.00</td></tr><tr><td>Has children</td><td>820</td><td>0.77</td><td>0.42</td><td>0.00</td><td>1.00</td></tr><tr><td>Completed secondary school</td><td>820</td><td>0.38</td><td>0.49</td><td>0.00</td><td>1.00</td></tr><tr><td>Cognitive (Raven's test score)</td><td>820</td><td>12.79</td><td>6.32</td><td>0.00</td><td>24.00</td></tr><tr><td>Works in garden a couple times a week</td><td>820</td><td>0.75</td><td>0.44</td><td>0.00</td><td>1.00</td></tr><tr><td>Fishes a couple times a week</td><td>820</td><td>0.46</td><td>0.50</td><td>0.00</td><td>1.00</td></tr><tr><td>Number of own relatives in village</td><td>820</td><td>2.96</td><td>2.64</td><td>0.00</td><td>15.00</td></tr><tr><td>Provides allocare to others</td><td>820</td><td>0.62</td><td>0.48</td><td>0.00</td><td>1.00</td></tr><tr><td>Number of own children</td><td>631</td><td>2.92</td><td>1.74</td><td>1.00</td><td>11.00</td></tr><tr><td>Cares for own children daily</td><td>631</td><td>0.71</td><td>0.45</td><td>0.00</td><td>1.00</td></tr><tr><td>Total number of allocarers</td><td>631</td><td>7.07</td><td>2.72</td><td>0.00</td><td>14.00</td></tr><tr><td>Daily allocare from spouse</td><td>631</td><td>0.52</td><td>0.50</td><td>0.00</td><td>1.00</td></tr><tr><td>Daily allocare (excl spouse)</td><td>631</td><td>0.62</td><td>0.49</td><td>0.00</td><td>1.00</td></tr><tr><td>Witness violence</td><td>819</td><td>0.47</td><td>0.50</td><td>0.00</td><td>1.00</td></tr><tr><td>Religiosity</td><td>820</td><td>3.30</td><td>1.34</td><td>0.00</td><td>6.00</td></tr><tr><td>Share sent in DG (Anonymous)</td><td>818</td><td>0.39</td><td>0.18</td><td>0.00</td><td>1.00</td></tr><tr><td>Share sent in DG (Non-Anonymous)</td><td>818</td><td>0.40</td><td>0.18</td><td>0.00</td><td>1.00</td></tr><tr><td colspan="6"><em>Child information</em></td></tr><tr><td>Age (months)</td><td>197</td><td>25.41</td><td>9.15</td><td>6.00</td><td>48.00</td></tr><tr><td>Female</td><td>197</td><td>0.47</td><td>0.50</td><td>0.00</td><td>1.00</td></tr><tr><td>Mother's partner not the biological father</td><td>197</td><td>0.17</td><td>0.37</td><td>0.00</td><td>1.00</td></tr><tr><td>Vocalizations (per hour)</td><td>197</td><td>215.47</td><td>82.08</td><td>0.00</td><td>525.30</td></tr><tr><td>Cortisol (pg/mg)</td><td>103</td><td>6.06</td><td>5.22</td><td>0.08</td><td>27.40</td></tr><tr><td>Cortisone (pg/mg)</td><td>103</td><td>23.15</td><td>15.50</td><td>1.91</td><td>101.70</td></tr></tbody></table>
<table><caption>Table B2: Accuracy of allom maternal care help: Comparing mothers' and fathers' answers</caption><thead><tr><th></th><th colspan="8">Allom maternal care from:</th></tr><tr><th></th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th></tr><tr><th></th><th>Mother's Mother</th><th>Mother's Mother</th><th>Father's Mother</th><th>Father's Mother</th><th>Mother's Father</th><th>Mother's Father</th><th>Father's Father</th><th>Father's Father</th></tr></thead><tbody><tr><th>Mother</th><td>0.057<br>(0.137)</td><td>-0.273<br>(0.148)</td><td>-0.279***<br>(0.056)</td><td>0.026<br>(0.062)</td><td>0.047<br>(0.092)</td><td>-0.059<br>(0.091)</td><td>-0.305***<br>(0.085)</td><td>0.094<br>(0.102)</td></tr><tr><th>Other support</th><td></td><td></td><td>✓</td><td></td><td>✓</td><td></td><td></td><td>✓</td></tr><tr><th>R-squared</th><td>0.03</td><td>0.41</td><td>0.06</td><td>0.44</td><td>0.10</td><td>0.50</td><td>0.10</td><td>0.31</td></tr><tr><th>Observations</th><td>298</td><td>298</td><td>285</td><td>285</td><td>258</td><td>258</td><td>215</td><td>215</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a parent in the paired mother-father sample. OLS estimates. The dependent variable in Column 1 is the help provided by the maternal grandmother (i.e. childcare help provided by the mother if the participant is the mother and the childcare help provided by the mother-in-law if the participant is the father). The dependent variable in Column 2 is the help provided by the paternal grandmother (i.e. mother-in-law if the participant is the mother, mother if the participant is the father). The dependent variable in Column 3 is the help provided by the maternal grandfather (i.e. father if the participant is the mother, father-in-law if the participant is the father). The dependent variable in Column 4 is the help provided by the paternal grandfather (i.e. father-in-law if the participant is the mother, father if the participant is the father). We standardize all dependent variables to have mean 0 and standard deviation of 1 and regress them on whether the respondent is the mother. All regressions with a constant and a household fixed effect. Robust standard errors clustered at the household level in parenthesis. Estimates in Columns 5 to 8 additionally control for “Other support”, i.e. financial (large or small), productive, and emotional support provided by the grandparent of interest (indicated in Columns) as well as for whether the participant and grandparent go to Church together.</footnote>
<table><caption>Table B3: Help with child care</caption><thead><tr><th></th><th>Mothers<br>(1)</th><th>Fathers<br>(2)</th><th>Overall<br>(3)</th><th>p-value<br>(1) vs. (2)</th></tr></thead><tbody><tr><td>Spouse</td><td>4.115<br>(0.075)</td><td>5.209<br>(0.057)</td><td>4.606<br>(0.054)</td><td><strong>0.000</strong></td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>305</td><td>249</td><td>554</td><td></td></tr><tr><td>Mother</td><td>2.977<br>(0.118)</td><td>2.884<br>(0.132)</td><td>2.940<br>(0.088)</td><td>0.605</td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>307</td><td>207</td><td>514</td><td></td></tr><tr><td>Father</td><td>2.428<br>(0.128)</td><td>2.429<br>(0.153)</td><td>2.429<br>(0.098)</td><td>0.994</td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>250</td><td>156</td><td>406</td><td></td></tr><tr><td>Sister</td><td>2.262<br>(0.108)</td><td>2.518<br>(0.123)</td><td>2.367<br>(0.081)</td><td>0.122</td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>325</td><td>226</td><td>551</td><td></td></tr><tr><td>Brother</td><td>1.596<br>(0.096)</td><td>1.912<br>(0.119)</td><td>1.726<br>(0.075)</td><td><strong>0.038</strong></td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>342</td><td>238</td><td>580</td><td></td></tr><tr><td>Mother in law</td><td>2.226<br>(0.132)</td><td>2.528<br>(0.141)</td><td>2.366<br>(0.096)</td><td>0.118</td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>226</td><td>197</td><td>423</td><td></td></tr><tr><td>Father in law</td><td>1.808<br>(0.151)</td><td>2.044<br>(0.151)</td><td>1.924<br>(0.107)</td><td>0.272</td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>167</td><td>160</td><td>327</td><td></td></tr><tr><td>Friend</td><td>2.752<br>(0.100)</td><td>1.996<br>(0.120)</td><td>2.434<br>(0.079)</td><td><strong>0.000</strong></td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>331</td><td>240</td><td>571</td><td></td></tr><tr><td>Neighbor</td><td>2.821<br>(0.095)</td><td>2.320<br>(0.122)</td><td>2.617<br>(0.076)</td><td><strong>0.001</strong></td></tr><tr><td>s.e.</td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>336</td><td>231</td><td>567</td><td></td></tr></tbody></table>

Entries represent average amount of help with care provided by named individual ranked as: (0) never, (1) less frequently than once a month, (2) more frequently than once a month, (3) once a week, (4) a few times a week, (5) every day, a little bit, or (6) every day, for a large part of the day. Standard errors in parentheses. T-tests p-values of differences between mothers and fathers averages.
<table><caption>Table B4: Determinants of allom maternal care</caption><thead><tr><th></th><th>(1)<br>Ln(age)</th><th>(2)<br>Cognitive</th><th>(3)<br>Wealth</th><th>(4)<br>School</th><th>(5)<br># Kids</th><th>(6)<br>Kin in vill</th><th>(7)<br>Care own</th><th>(8)<br>Allo others</th><th>(9)<br>Gardens</th><th>(10)<br>Fishing</th><th>(11)<br>Market</th><th>(12)<br>Violence</th></tr></thead><tbody><tr><td colspan="13"><strong>Panel A: Mothers</strong></td></tr><tr><td colspan="13"><em>Total amount of help with child care</em></td></tr><tr><td>Child care</td><td>-0.051***<br>(0.010)</td><td>0.039<br>(0.284)</td><td>0.049<br>(0.093)</td><td>-0.024<br>(0.022)</td><td>-0.141<br>(0.090)</td><td>0.685***<br>(0.167)</td><td>0.168***<br>(0.061)</td><td>0.057<br>(0.055)</td><td>0.158***<br>(0.056)</td><td>0.186***<br>(0.052)</td><td>0.168***<br>(0.043)</td><td>0.007<br>(0.026)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from spouse</em></td></tr><tr><td>Child care from spouse</td><td>-0.025**<br>(0.012)</td><td>0.270<br>(0.417)</td><td>0.010<br>(0.095)</td><td>0.031<br>(0.028)</td><td>-0.066<br>(0.099)</td><td>-0.008<br>(0.167)</td><td>0.103<br>(0.067)</td><td>-0.019<br>(0.053)</td><td>0.033<br>(0.047)</td><td>-0.087<br>(0.069)</td><td>0.081<br>(0.057)</td><td>-0.006<br>(0.028)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from relatives of child</em></td></tr><tr><td>Child care from relatives</td><td>-0.061***<br>(0.010)</td><td>0.226<br>(0.291)</td><td>0.063<br>(0.095)</td><td>-0.007<br>(0.023)</td><td>-0.336***<br>(0.091)</td><td>0.914***<br>(0.138)</td><td>0.124**<br>(0.057)</td><td>0.023<br>(0.053)</td><td>0.091<br>(0.063)</td><td>0.180***<br>(0.047)</td><td>0.090**<br>(0.044)</td><td>0.018<br>(0.024)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from non-relatives</em></td></tr><tr><td>Child care from non-relatives</td><td>-0.016<br>(0.013)</td><td>-0.134<br>(0.279)</td><td>-0.017<br>(0.095)</td><td>-0.034<br>(0.021)</td><td>0.069<br>(0.083)</td><td>0.203<br>(0.147)</td><td>0.163***<br>(0.053)</td><td>0.164***<br>(0.048)</td><td>0.142**<br>(0.068)</td><td>0.129**<br>(0.060)</td><td>0.202***<br>(0.047)</td><td>0.003<br>(0.030)</td></tr><tr><td>Observations</td><td>372</td><td>373</td><td>373</td><td>373</td><td>373</td><td>373</td><td>373</td><td>373</td><td>373</td><td>373</td><td>372</td><td>373</td></tr><tr><td colspan="13"><strong>Panel B: Fathers</strong></td></tr><tr><td colspan="13"><em>Total amount of help with child care</em></td></tr><tr><td>Child care</td><td>-0.066***<br>(0.012)</td><td>-0.573<br>(0.389)</td><td>0.006<br>(0.104)</td><td>0.019<br>(0.031)</td><td>-0.277**<br>(0.122)</td><td>0.694***<br>(0.199)</td><td>0.217**<br>(0.086)</td><td>0.201***<br>(0.064)</td><td>0.036<br>(0.074)</td><td>0.032<br>(0.052)</td><td>0.049<br>(0.062)</td><td>0.035<br>(0.036)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from spouse</em></td></tr><tr><td>Child care from spouse</td><td>-0.019<br>(0.020)</td><td>-0.465<br>(0.540)</td><td>-0.059<br>(0.150)</td><td>0.067<br>(0.048)</td><td>0.058<br>(0.149)</td><td>0.118<br>(0.218)</td><td>0.182<br>(0.135)</td><td>-0.005<br>(0.096)</td><td>0.016<br>(0.074)</td><td>0.105<br>(0.085)</td><td>-0.140<br>(0.087)</td><td>-0.041<br>(0.047)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from relatives of child</em></td></tr><tr><td>Child care from relatives</td><td>-0.060***<br>(0.012)</td><td>-0.163<br>(0.445)</td><td>-0.068<br>(0.101)</td><td>0.023<br>(0.024)</td><td>-0.300**<br>(0.118)</td><td>0.829***<br>(0.182)</td><td>0.131*<br>(0.067)</td><td>0.171**<br>(0.066)</td><td>0.045<br>(0.067)</td><td>0.019<br>(0.051)</td><td>0.061<br>(0.060)</td><td>0.019<br>(0.033)</td></tr><tr><td colspan="13"><em>Total amount of help with child care from non-relatives</em></td></tr><tr><td>Child care from non-relatives</td><td>-0.054***<br>(0.013)</td><td>-0.998**<br>(0.397)</td><td>0.188*<br>(0.102)</td><td>-0.002<br>(0.037)</td><td>-0.224<br>(0.139)</td><td>0.090<br>(0.204)</td><td>0.192**<br>(0.075)</td><td>0.193***<br>(0.060)</td><td>-0.007<br>(0.068)</td><td>0.031<br>(0.054)</td><td>0.032<br>(0.060)</td><td>0.076*<br>(0.039)</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>253</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td><td>255</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant who has children. Each cell displays the coefficient and standard error (in parentheses) of a separate regression of each care variable (listed in rows) on the characteristic listed in Columns, controlling for village fixed effects and adjusting standard errors for clustering at the village level. Child care variables normalized to mean zero, standard deviation one.</footnote>
<table><caption>Table B5: Correlations between allom maternal care and other forms of support</caption><thead><tr><th>DV: Amount of help with care</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th><th>(9)</th><th>(10)</th></tr><tr><th></th><th colspan="5">Mothers</th><th colspan="5">Fathers</th></tr></thead><tbody><tr><td>Small financial support (0/1)</td><td>0.375***<br>(0.048)</td><td></td><td></td><td></td><td></td><td>0.197***<br>(0.057)</td><td></td><td></td><td></td><td></td></tr><tr><td>Large financial support (0/1)</td><td></td><td>0.125**<br>(0.057)</td><td></td><td></td><td></td><td></td><td>-0.007<br>(0.070)</td><td></td><td></td><td></td></tr><tr><td>Help with production</td><td></td><td></td><td>0.462***<br>(0.024)</td><td></td><td></td><td></td><td></td><td>0.414***<br>(0.029)</td><td></td><td></td></tr><tr><td>Emotional support</td><td></td><td></td><td></td><td>0.272***<br>(0.026)</td><td></td><td></td><td></td><td></td><td>0.288***<br>(0.028)</td><td></td></tr><tr><td>Attend same church (0/1)</td><td></td><td></td><td></td><td></td><td>0.738***<br>(0.073)</td><td></td><td></td><td></td><td></td><td>0.713***<br>(0.075)</td></tr><tr><td>Participant FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Receiver type FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>2347</td><td>2347</td><td>2347</td><td>2345</td><td>2342</td><td>1764</td><td>1764</td><td>1764</td><td>1764</td><td>1760</td></tr><tr><td>R<sup>2</sup></td><td>0.429</td><td>0.411</td><td>0.529</td><td>0.453</td><td>0.463</td><td>0.485</td><td>0.480</td><td>0.573</td><td>0.523</td><td>0.518</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, excluding strangers. Standard errors clustered at the participant level in parentheses. Amount of help with child care, production, and emotional support standardized to mean zero, standard deviation one.</footnote>
<table><caption>Table B6: Dictator game giving in anonymous (strong reciprocity) and non-anonymous (weak reciprocity) conditions, by mothers and fathers</caption><thead><tr><th rowspan="2"></th><th colspan="3">Mothers</th><th colspan="3">Fathers</th><th colspan="2">Mothers v. Fathers</th></tr><tr><th>Strong Reciprocity (1)</th><th>Weak Reciprocity (2)</th><th>Paired t-test (1)vs.(2) p-value</th><th>Strong Reciprocity (3)</th><th>Weak Reciprocity (4)</th><th>Paired t-test (3)vs.(4) p-value</th><th>Strong Reciprocity (1)vs.(3) p-value</th><th>Weak Reciprocity (2)vs.(4) p-value</th></tr></thead><tbody><tr><td>Spouse</td><td>0.48<br>(0.016)</td><td>0.478<br>(0.017)</td><td>0.840<br>N=292</td><td>0.557<br>(0.017)</td><td>0.567<br>(0.017)</td><td>0.495<br>N=238</td><td><strong>0.001</strong></td><td><strong>0.000</strong></td></tr><tr><td>Mother</td><td>0.483<br>(0.016)</td><td>0.501<br>(0.017)</td><td>0.211<br>N=295</td><td>0.5<br>(0.019)</td><td>0.499<br>(0.019)</td><td>0.943<br>N=206</td><td>0.492</td><td>0.936</td></tr><tr><td>Father</td><td>0.484<br>(0.018)</td><td>0.519<br>(0.019)</td><td><strong>0.034<br>N=241</strong></td><td>0.49<br>(0.022)</td><td>0.503<br>(0.022)</td><td>0.390<br>N=168</td><td>0.858</td><td>0.596</td></tr><tr><td>Sister</td><td>0.389<br>(0.014)</td><td>0.387<br>(0.014)</td><td>0.895<br>N=323</td><td>0.38<br>(0.015)</td><td>0.374<br>(0.014)</td><td>0.575<br>N=220</td><td>0.672</td><td>0.519</td></tr><tr><td>Brother</td><td>0.362<br>(0.013)</td><td>0.371<br>(0.014)</td><td>0.421<br>N=325</td><td>0.38<br>(0.016)</td><td>0.398<br>(0.015)</td><td>0.150<br>N=229</td><td>0.375</td><td>0.182</td></tr><tr><td>Mother in law</td><td>0.374<br>(0.018)</td><td>0.365<br>(0.018)</td><td>0.570<br>N=208</td><td>0.366<br>(0.018)</td><td>0.371<br>(0.018)</td><td>0.757<br>N=198</td><td>0.764</td><td>0.818</td></tr><tr><td>Father in law</td><td>0.324<br>(0.020)</td><td>0.36<br>(0.021)</td><td><strong>0.024<br>N=178</strong></td><td>0.384<br>(0.021)</td><td>0.378<br>(0.020)</td><td>0.737<br>N=160</td><td><strong>0.040</strong></td><td>0.522</td></tr><tr><td>Friend</td><td>0.315<br>(0.013)</td><td>0.339<br>(0.013)</td><td><strong>0.018<br>N=324</strong></td><td>0.315<br>(0.013)</td><td>0.324<br>(0.014)</td><td>0.360<br>N=233</td><td>0.974</td><td>0.455</td></tr><tr><td>Neighbor</td><td>0.309<br>(0.013)</td><td>0.321<br>(0.013)</td><td>0.327<br>N=319</td><td>0.316<br>(0.014)</td><td>0.314<br>(0.014)</td><td>0.830<br>N=223</td><td>0.700</td><td>0.739</td></tr><tr><td>Stranger same village</td><td>0.273<br>(0.012)</td><td>0.294<br>(0.012)</td><td>0.083<br>N=362</td><td>0.283<br>(0.014)</td><td>0.319<br>(0.015)</td><td><strong>0.013<br>N=249</strong></td><td>0.610</td><td>0.191</td></tr><tr><td>Stranger distant village</td><td>0.25<br>(0.014)</td><td>0.256<br>(0.013)</td><td>0.639<br>N=360</td><td>0.267<br>(0.016)</td><td>0.268<br>(0.017)</td><td>0.947<br>N=235</td><td>0.430</td><td>0.559</td></tr></tbody></table>

Entries represent average share of endowment transferred to each receiver under anonymous (Altruism) and non-anonymous (Reciprocity) conditions. Standard errors in parentheses. Paired t-test p-values for testing differences between conditions by sender. Independent samples t-test p-values for testing differences between sexes, within condition.
<table><caption>Table B7: Dictator game giving to strangers, by help from non-relatives (low, high), non-anonymous (weak reciprocity) and anonymous (strong reciprocity) conditions, and type of stranger, for mothers and fathers</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Help from non-relatives</th><th colspan="3">Mothers</th><th colspan="3">Fathers</th></tr><tr><th>Strong Reciprocity (1)</th><th>Weak Reciprocity (2)</th><th>Paired t-test (1)vs.(2) p-value</th><th>Strong Reciprocity (3)</th><th>Weak Reciprocity (4)</th><th>Paired t-test (3)vs.(4) p-value</th></tr></thead><tbody><tr><td rowspan="2">Stranger distant village</td><td>Low help</td><td>0.204<br>(0.018)</td><td>0.211<br>(0.018)</td><td>0.687<br>N=181</td><td>0.250<br>(0.021)</td><td>0.230<br>(0.020)</td><td>0.315<br>N=141</td></tr><tr><td>High help</td><td>0.296<br>(0.020)</td><td>0.300<br>(0.020)</td><td>0.799<br>N=179</td><td>0.293<br>(0.025)</td><td>0.324<br>(0.027)</td><td>0.241<br>N=94</td></tr><tr><td colspan="2">t-test p-value (low) vs. (high)</td><td><strong>0.001</strong></td><td><strong>0.001</strong></td><td></td><td>0.203</td><td><strong>0.005</strong></td><td></td></tr><tr><td rowspan="2">Stranger same village</td><td>Low help</td><td>0.232<br>(0.017)</td><td>0.264<br>(0.017)</td><td>0.068<br>N=184</td><td>0.252<br>(0.018)</td><td>0.290<br>(0.018)</td><td>0.026<br>N=150</td></tr><tr><td>High help</td><td>0.316<br>(0.017)</td><td>0.326<br>(0.018)</td><td>0.557<br>N=178</td><td>0.331<br>(0.023)</td><td>0.364<br>(0.023)</td><td>0.206<br>N=99</td></tr><tr><td colspan="2">t-test p-value (low) vs. (high)</td><td><strong>0.001</strong></td><td><strong>0.012</strong></td><td></td><td><strong>0.007</strong></td><td><strong>0.013</strong></td><td></td></tr></tbody></table>

Entries represent average share of endowment transferred by help (low, high) under anonymous (altruism) and non-anonymous (reciprocity) conditions. Standard errors in parentheses. Paired t-test p-values for differences between conditions. Independent samples t-test p-values for differences between levels of help.
<table><caption>Table B8: Allomaterial care and dictator game giving to strangers, adding an interaction between same village and weak reciprocity</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th></tr><tr><th></th><th colspan="4">Mothers</th><th colspan="4">Fathers</th></tr></thead><tbody><tr><td>Care from: Spouse</td><td>-0.004<br>(0.008)</td><td>-0.002<br>(0.009)</td><td>-0.004<br>(0.010)</td><td>-0.002<br>(0.012)</td><td>0.005<br>(0.018)</td><td>0.000<br>(0.020)</td><td>0.019<br>(0.021)</td><td>0.013<br>(0.021)</td></tr><tr><td>Care from: Relatives of child</td><td>-0.014<br>(0.010)</td><td>-0.013<br>(0.014)</td><td>-0.011<br>(0.014)</td><td>-0.009<br>(0.017)</td><td>0.021*<br>(0.012)</td><td>0.022<br>(0.017)</td><td>0.013<br>(0.016)</td><td>0.014<br>(0.019)</td></tr><tr><td>Care from: Non-relatives</td><td>0.024**<br>(0.011)</td><td>0.027**<br>(0.011)</td><td>0.024*<br>(0.013)</td><td>0.027*<br>(0.013)</td><td>0.013<br>(0.015)</td><td>0.019<br>(0.016)</td><td>0.014<br>(0.019)</td><td>0.020<br>(0.020)</td></tr><tr><td>Same village × Care from: Spouse</td><td></td><td></td><td>0.003<br>(0.010)</td><td>0.003<br>(0.010)</td><td></td><td></td><td>-0.024<br>(0.019)</td><td>-0.023<br>(0.019)</td></tr><tr><td>Same village × Care from: Relatives of child</td><td></td><td></td><td>0.009<br>(0.009)</td><td>0.008<br>(0.009)</td><td></td><td></td><td>0.003<br>(0.015)</td><td>0.005<br>(0.015)</td></tr><tr><td>Same village × Care from: Non-relatives</td><td></td><td></td><td>-0.005<br>(0.008)</td><td>-0.005<br>(0.008)</td><td></td><td></td><td>-0.004<br>(0.016)</td><td>-0.006<br>(0.015)</td></tr><tr><td>Non-Anonymous × Care from: Spouse</td><td></td><td></td><td>-0.003<br>(0.009)</td><td>-0.003<br>(0.009)</td><td></td><td></td><td>-0.003<br>(0.016)</td><td>-0.003<br>(0.016)</td></tr><tr><td>Non-Anonymous × Care from: Relatives of child</td><td></td><td></td><td>-0.016<br>(0.010)</td><td>-0.016<br>(0.010)</td><td></td><td></td><td>0.011<br>(0.012)</td><td>0.011<br>(0.013)</td></tr><tr><td>Non-Anonymous × Care from: Non-relatives</td><td></td><td></td><td>0.005<br>(0.008)</td><td>0.005<br>(0.008)</td><td></td><td></td><td>0.003<br>(0.014)</td><td>0.003<br>(0.014)</td></tr><tr><td>Same village</td><td>0.023<br>(0.015)</td><td>0.022<br>(0.015)</td><td>0.025*<br>(0.014)</td><td>0.025*<br>(0.014)</td><td>0.017<br>(0.013)</td><td>0.016<br>(0.014)</td><td>0.028*<br>(0.016)</td><td>0.026<br>(0.017)</td></tr><tr><td>Non-Anonymous</td><td>0.006<br>(0.012)</td><td>0.006<br>(0.012)</td><td>0.002<br>(0.013)</td><td>0.002<br>(0.013)</td><td>0.001<br>(0.019)</td><td>0.001<br>(0.019)</td><td>0.002<br>(0.021)</td><td>0.002<br>(0.021)</td></tr><tr><td>Same village × Non-Anonymous</td><td>0.015<br>(0.015)</td><td>0.015<br>(0.015)</td><td>0.015<br>(0.015)</td><td>0.015<br>(0.015)</td><td>0.035*<br>(0.020)</td><td>0.035*<br>(0.020)</td><td>0.035*<br>(0.020)</td><td>0.035*<br>(0.020)</td></tr><tr><td>Emotional support</td><td></td><td></td><td>-0.000<br>(0.013)</td><td>-0.000<br>(0.013)</td><td></td><td></td><td>-0.031**<br>(0.015)</td><td>-0.031**<br>(0.015)</td></tr><tr><td>Small financial support</td><td></td><td></td><td>0.004<br>(0.012)</td><td>0.004<br>(0.012)</td><td></td><td></td><td>0.003<br>(0.015)</td><td>0.003<br>(0.015)</td></tr><tr><td>Large financial support</td><td></td><td></td><td>-0.010<br>(0.010)</td><td>-0.010<br>(0.010)</td><td></td><td></td><td>-0.013<br>(0.014)</td><td>-0.013<br>(0.014)</td></tr><tr><td>Production support</td><td></td><td></td><td>-0.021<br>(0.016)</td><td>-0.021<br>(0.016)</td><td></td><td></td><td>0.023<br>(0.018)</td><td>0.023<br>(0.018)</td></tr><tr><td>Church congregants</td><td></td><td></td><td>0.011<br>(0.013)</td><td>0.011<br>(0.013)</td><td></td><td></td><td>0.015<br>(0.014)</td><td>0.014<br>(0.014)</td></tr><tr><td>Additional controls:</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Villages</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td></tr><tr><td>Observations</td><td>1444</td><td>1444</td><td>1444</td><td>1444</td><td>968</td><td>968</td><td>968</td><td>968</td></tr><tr><td>R<sup>2</sup></td><td>0.247</td><td>0.276</td><td>0.249</td><td>0.277</td><td>0.219</td><td>0.264</td><td>0.221</td><td>0.266</td></tr><tr><td>δ Care from: Non-relatives</td><td></td><td>1.87</td><td></td><td>-2.73</td><td></td><td>3.61</td><td></td><td>-2.75</td></tr><tr><td>Mean DV</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.28</td><td>0.28</td><td>0.28</td><td>0.28</td></tr><tr><td>SD DV</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.24</td><td>0.24</td><td>0.24</td><td>0.24</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, restricted to strangers, only. All estimates include village fixed effects. Additional controls include log of participant's age, cognitive ability, number of children, number of relatives living in the village, ownership of consumer durables, whether the participant ever witnessed inter-village violence, and religiosity. Care variables represent the amount of help with child care that each group provides to the participant standardized to mean zero, standard deviation one. Non-Anonymous is an indicator variable taking value one for the non-anonymous giving condition. Support variables represent the total amount of support, for each type of support as described in the main text, received from the various individuals in a participant's network, normalized to mean zero, standard deviation one. Standard errors clustered at the village level in parentheses. The coefficients δ are calculated using the psacalc function in Stata assuming an R-max = 1.3 * R<sup>2</sup> and represent the proportional degree of selection on unobservables needed to overturn the estimated effects. Missing observations imputed to the sample mean for control variables and all estimates include indicator variables for missing observations.</footnote>
<table><caption>Table B9: Allomaterial care and dictator game giving to strangers (full controls)</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th></tr><tr><th></th><th colspan="4">Mothers</th><th colspan="4">Fathers</th></tr></thead><tbody><tr><td>Care from: Spouse</td><td>-0.004<br>(0.008)</td><td>-0.002<br>(0.009)</td><td>-0.004<br>(0.010)</td><td>-0.002<br>(0.012)</td><td>0.005<br>(0.018)</td><td>0.000<br>(0.020)</td><td>0.019<br>(0.021)</td><td>0.013<br>(0.021)</td></tr><tr><td>Care from: Relatives of child</td><td>-0.014<br>(0.010)</td><td>-0.013<br>(0.014)</td><td>-0.011<br>(0.014)</td><td>-0.009<br>(0.017)</td><td>0.021*<br>(0.012)</td><td>0.022<br>(0.017)</td><td>0.013<br>(0.016)</td><td>0.014<br>(0.019)</td></tr><tr><td>Care from: Non-relatives</td><td>0.024**<br>(0.011)</td><td>0.027**<br>(0.011)</td><td>0.024*<br>(0.013)</td><td>0.027*<br>(0.013)</td><td>0.013<br>(0.015)</td><td>0.019<br>(0.016)</td><td>0.014<br>(0.019)</td><td>0.020<br>(0.020)</td></tr><tr><td>Same village × Care from: Spouse</td><td></td><td></td><td>0.003<br>(0.010)</td><td>0.003<br>(0.010)</td><td></td><td></td><td>-0.024<br>(0.019)</td><td>-0.023<br>(0.019)</td></tr><tr><td>Same village × Care from: Relatives of child</td><td></td><td></td><td>0.009<br>(0.009)</td><td>0.008<br>(0.009)</td><td></td><td></td><td>0.003<br>(0.015)</td><td>0.005<br>(0.015)</td></tr><tr><td>Same village × Care from: Non-relatives</td><td></td><td></td><td>-0.005<br>(0.008)</td><td>-0.005<br>(0.008)</td><td></td><td></td><td>-0.004<br>(0.016)</td><td>-0.006<br>(0.015)</td></tr><tr><td>Non-Anonymous × Care from: Spouse</td><td></td><td></td><td>-0.003<br>(0.009)</td><td>-0.003<br>(0.009)</td><td></td><td></td><td>-0.003<br>(0.016)</td><td>-0.003<br>(0.016)</td></tr><tr><td>Non-Anonymous × Care from: Relatives of child</td><td></td><td></td><td>-0.016<br>(0.010)</td><td>-0.016<br>(0.010)</td><td></td><td></td><td>0.011<br>(0.012)</td><td>0.011<br>(0.013)</td></tr><tr><td>Non-Anonymous × Care from: Non-relatives</td><td></td><td></td><td>0.005<br>(0.008)</td><td>0.005<br>(0.008)</td><td></td><td></td><td>0.003<br>(0.014)</td><td>0.003<br>(0.014)</td></tr><tr><td>Same village</td><td>0.030**<br>(0.013)</td><td>0.030**<br>(0.013)</td><td>0.033**<br>(0.013)</td><td>0.032**<br>(0.013)</td><td>0.034***<br>(0.011)</td><td>0.034***<br>(0.011)</td><td>0.045***<br>(0.016)</td><td>0.044**<br>(0.016)</td></tr><tr><td>Non-Anonymous</td><td>0.013<br>(0.010)</td><td>0.013<br>(0.010)</td><td>0.010<br>(0.012)</td><td>0.010<br>(0.012)</td><td>0.019<br>(0.015)</td><td>0.019<br>(0.015)</td><td>0.020<br>(0.019)</td><td>0.020<br>(0.019)</td></tr><tr><td>Emotional support</td><td></td><td></td><td>-0.000<br>(0.013)</td><td>-0.000<br>(0.013)</td><td></td><td></td><td>-0.031**<br>(0.015)</td><td>-0.031**<br>(0.015)</td></tr><tr><td>Small financial support</td><td></td><td></td><td>0.004<br>(0.012)</td><td>0.004<br>(0.012)</td><td></td><td></td><td>0.003<br>(0.015)</td><td>0.003<br>(0.015)</td></tr><tr><td>Large financial support</td><td></td><td></td><td>-0.010<br>(0.010)</td><td>-0.010<br>(0.010)</td><td></td><td></td><td>-0.013<br>(0.014)</td><td>-0.013<br>(0.014)</td></tr><tr><td>Production support</td><td></td><td></td><td>-0.021<br>(0.016)</td><td>-0.021<br>(0.016)</td><td></td><td></td><td>0.023<br>(0.018)</td><td>0.023<br>(0.018)</td></tr><tr><td>Church congregants</td><td></td><td></td><td>0.011<br>(0.013)</td><td>0.011<br>(0.013)</td><td></td><td></td><td>0.015<br>(0.014)</td><td>0.014<br>(0.014)</td></tr><tr><td>Ln(age)</td><td></td><td></td><td>0.006<br>(0.048)</td><td>0.006<br>(0.048)</td><td></td><td></td><td>0.110<br>(0.079)</td><td>0.110<br>(0.079)</td></tr><tr><td>Cognitive ability</td><td></td><td></td><td>-0.022<br>(0.013)</td><td>-0.022<br>(0.013)</td><td></td><td></td><td>-0.036***<br>(0.010)</td><td>-0.036***<br>(0.010)</td></tr><tr><td>Consumer durables</td><td></td><td></td><td>-0.011<br>(0.010)</td><td>-0.011<br>(0.010)</td><td></td><td></td><td>-0.029*<br>(0.016)</td><td>-0.029*<br>(0.016)</td></tr><tr><td>Number of relatives in village</td><td></td><td></td><td>0.003<br>(0.005)</td><td>0.004<br>(0.005)</td><td></td><td></td><td>-0.001<br>(0.005)</td><td>-0.001<br>(0.005)</td></tr><tr><td>Time in gardens</td><td></td><td></td><td>0.030***<br>(0.009)</td><td>0.030***<br>(0.009)</td><td></td><td></td><td>-0.024<br>(0.016)</td><td>-0.023<br>(0.016)</td></tr><tr><td>Time selling in other village</td><td></td><td></td><td>-0.007<br>(0.013)</td><td>-0.007<br>(0.013)</td><td></td><td></td><td>0.001<br>(0.012)</td><td>0.001<br>(0.012)</td></tr><tr><td>Witness violence (0/1)</td><td></td><td></td><td>-0.043*<br>(0.022)</td><td>-0.043*<br>(0.022)</td><td></td><td></td><td>-0.015<br>(0.029)</td><td>-0.015<br>(0.029)</td></tr><tr><td>Religiosity</td><td></td><td></td><td>-0.004<br>(0.009)</td><td>-0.004<br>(0.009)</td><td></td><td></td><td>0.006<br>(0.013)</td><td>0.006<br>(0.013)</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Villages</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td><td>44</td></tr><tr><td>Observations</td><td>1444</td><td>1444</td><td>1444</td><td>1444</td><td>968</td><td>968</td><td>968</td><td>968</td></tr><tr><td>R<sup>2</sup></td><td>0.247</td><td>0.276</td><td>0.249</td><td>0.277</td><td>0.218</td><td>0.262</td><td>0.220</td><td>0.264</td></tr><tr><td>δ Care from: Non-relatives</td><td></td><td>1.87</td><td></td><td>-2.74</td><td></td><td>3.63</td><td></td><td>-2.76</td></tr><tr><td>Mean DV</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.27</td><td>0.28</td><td>0.28</td><td>0.28</td><td>0.28</td></tr><tr><td>SD DV</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.25</td><td>0.24</td><td>0.24</td><td>0.24</td><td>0.24</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, restricted to strangers, only. All estimates include village fixed effects. Care variables represent the amount of help with child care that each group provides to the participant standardized to mean zero, standard deviation one. Non-Anonymous is an indicator variable taking value one for the non-anonymous giving condition. Support variables represent the total amount of support received from the various individuals in a participant's network, normalized to mean zero, standard deviation one. Standard errors clustered at the village level in parentheses. The coefficients δ are calculated using the psacalc function in Stata assuming an R-max = 1.3 * R² and represent the proportional degree of selection on unobservables needed to overturn the estimated effects. Missing observations imputed to the sample mean for control variables and all estimates include indicator variables for missing observations.</footnote>
<table><caption>Table B10: Allomaterial care and dictator game giving to strangers (people without children)</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th></tr></thead><tbody><tr><td>Child care</td><td>0.022**<br>(0.010)</td><td>0.024**<br>(0.011)</td><td>0.023**<br>(0.012)</td><td></td><td></td><td></td></tr><tr><td>Women × Child care</td><td></td><td>-0.006<br>(0.015)</td><td>-0.001<br>(0.015)</td><td></td><td></td><td></td></tr><tr><td>Child care from non-relatives</td><td></td><td></td><td></td><td>0.004<br>(0.010)</td><td>-0.012<br>(0.013)</td><td>-0.006<br>(0.014)</td></tr><tr><td>Women × Child care from non-relatives</td><td></td><td></td><td></td><td></td><td>0.039**<br>(0.017)</td><td>0.055***<br>(0.018)</td></tr><tr><td>Women</td><td>-0.018<br>(0.020)</td><td>-0.017<br>(0.020)</td><td>-0.049**<br>(0.021)</td><td>-0.017<br>(0.020)</td><td>-0.020<br>(0.020)</td><td>-0.054***<br>(0.021)</td></tr><tr><td>Same village</td><td>0.044**<br>(0.017)</td><td>0.044**<br>(0.017)</td><td>0.044**<br>(0.017)</td><td>0.043**<br>(0.018)</td><td>0.044**<br>(0.017)</td><td>0.043**<br>(0.017)</td></tr><tr><td>Non-Anonymous</td><td>0.013<br>(0.017)</td><td>0.013<br>(0.017)</td><td>0.013<br>(0.017)</td><td>0.013<br>(0.017)</td><td>0.013<br>(0.017)</td><td>0.013<br>(0.017)</td></tr><tr><td>Indiv. controls:</td><td>N</td><td>N</td><td>Y</td><td>N</td><td>N</td><td>Y</td></tr><tr><td>R<sup>2</sup></td><td>0.024</td><td>0.025</td><td>0.105</td><td>0.018</td><td>0.024</td><td>0.112</td></tr><tr><td>Observations</td><td>710</td><td>710</td><td>706</td><td>710</td><td>710</td><td>706</td></tr><tr><td>Mean DV</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td></tr><tr><td>SD DV</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, restricted to strangers. Participant sample is restricted to participants who do not have children. All estimates control for a province fixed effect, as well as whether the stranger is from a distant village and whether the transfer was anonymous or non-anonymous. *Child care* represents the average amount of help with child care that parents receive in the participant's village, standardized to mean zero, standard deviation one. *Non-Anonymous* is an indicator variable taking value one for the non-anonymous giving condition. Individual controls are: log of participant's age, cognitive ability, number of relatives living in the village, ownership of consumer durables, whether the participant ever witnessed inter-village violence, and religiosity. Robust standard errors in parentheses.</footnote>
<table><caption>Table B11: Allomaterial care and dictator game giving to strangers (people without children), adding an interaction between same village and reciprocity</caption><thead><tr><th>DV: Share sent in DG</th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th></tr></thead><tbody><tr><td>Child care</td><td>0.022**<br>(0.010)</td><td>0.024**<br>(0.011)</td><td>0.023**<br>(0.012)</td><td></td><td></td><td></td></tr><tr><td>Women × Child care</td><td></td><td>-0.006<br>(0.015)</td><td>-0.001<br>(0.015)</td><td></td><td></td><td></td></tr><tr><td>Child care from non-relatives</td><td></td><td></td><td></td><td>0.004<br>(0.010)</td><td>-0.012<br>(0.013)</td><td>-0.006<br>(0.014)</td></tr><tr><td>Women × Child care from non-relatives</td><td></td><td></td><td></td><td></td><td>0.039**<br>(0.018)</td><td>0.055***<br>(0.018)</td></tr><tr><td>Women</td><td>-0.018<br>(0.020)</td><td>-0.017<br>(0.020)</td><td>-0.049**<br>(0.021)</td><td>-0.017<br>(0.020)</td><td>-0.020<br>(0.020)</td><td>-0.054***<br>(0.021)</td></tr><tr><td>Same village</td><td>0.044*<br>(0.025)</td><td>0.044*<br>(0.025)</td><td>0.042*<br>(0.024)</td><td>0.043*<br>(0.025)</td><td>0.043*<br>(0.025)</td><td>0.042*<br>(0.024)</td></tr><tr><td>Non-Anonymous</td><td>0.013<br>(0.026)</td><td>0.013<br>(0.026)</td><td>0.012<br>(0.025)</td><td>0.013<br>(0.026)</td><td>0.013<br>(0.026)</td><td>0.012<br>(0.025)</td></tr><tr><td>Same village × Non-Anonymous</td><td>0.001<br>(0.035)</td><td>0.001<br>(0.035)</td><td>0.003<br>(0.034)</td><td>0.001<br>(0.035)</td><td>0.001<br>(0.035)</td><td>0.003<br>(0.034)</td></tr><tr><td>Indiv. controls:</td><td>N</td><td>N</td><td>Y</td><td>N</td><td>N</td><td>Y</td></tr><tr><td>R<sup>2</sup></td><td>0.024</td><td>0.025</td><td>0.105</td><td>0.018</td><td>0.024</td><td>0.112</td></tr><tr><td>Observations</td><td>710</td><td>710</td><td>706</td><td>710</td><td>710</td><td>706</td></tr><tr><td>Mean DV</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td><td>0.30</td></tr><tr><td>SD DV</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td><td>0.23</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a participant-receiver dyad in the dictator game, restricted to strangers. Participant sample is restricted to participants who do not have children. All estimates control for a province fixed effect, as well as whether the stranger is from a distant village and whether the transfer was anonymous or non-anonymous. *Child care* represents the average amount of help with child care that parents receive in the participant's village, standardized to mean zero, standard deviation one. *Non-Anonymous* is an indicator variable taking value one for the non-anonymous giving condition. Individual controls are: log of participant's age, cognitive ability, number of relatives living in the village, ownership of consumer durables, whether the participant ever witnessed inter-village violence, and religiosity. Robust standard errors in parentheses.</footnote>
<table><caption>Table B12: Robustness: Allomaterial care and child vocalizations (full controls)</caption><thead><tr><th></th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th></tr></thead><tbody><tr><td colspan="6"><strong>Panel B: Vocalizations per hour – Extended controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>1.599<br>(6.133)</td><td></td><td></td><td>2.578<br>(6.156)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-13.767<br>(10.403)</td><td></td><td>-14.264<br>(10.307)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-1.236<br>(17.902)</td><td>-3.072<br>(18.655)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>31.008**<br>(13.208)</td><td>31.174**<br>(13.175)</td></tr><tr><td>Mother's cognitive ability</td><td>0.850<br>(0.940)</td><td>0.865<br>(0.924)</td><td>0.863<br>(0.928)</td><td>0.859<br>(0.912)</td><td>0.807<br>(0.928)</td></tr><tr><td>Consumer durables</td><td>1.126<br>(3.391)</td><td>1.513<br>(3.437)</td><td>0.980<br>(3.418)</td><td>0.815<br>(3.355)</td><td>1.723<br>(3.343)</td></tr><tr><td>Emotional support</td><td>-7.977<br>(6.370)</td><td>-6.612<br>(6.478)</td><td>-8.004<br>(6.502)</td><td>-9.911<br>(6.646)</td><td>-8.258<br>(6.793)</td></tr><tr><td>Small financial support</td><td>3.636<br>(7.856)</td><td>1.766<br>(7.877)</td><td>3.779<br>(7.652)</td><td>6.490<br>(7.586)</td><td>4.008<br>(8.188)</td></tr><tr><td>Large financial support</td><td>-12.278*<br>(6.358)</td><td>-12.322*<br>(6.390)</td><td>-12.161*<br>(6.439)</td><td>-13.683**<br>(6.442)</td><td>-14.213**<br>(6.408)</td></tr><tr><td>Production support</td><td>-3.905<br>(6.719)</td><td>-2.511<br>(6.523)</td><td>-3.959<br>(6.638)</td><td>-6.081<br>(6.836)</td><td>-4.168<br>(6.694)</td></tr><tr><td>Church congregants</td><td>10.578<br>(6.928)</td><td>9.998<br>(6.513)</td><td>10.359<br>(6.862)</td><td>7.966<br>(6.689)</td><td>8.242<br>(6.805)</td></tr><tr><td>Witness violence (0/1)</td><td>-10.053<br>(13.056)</td><td>-9.241<br>(12.551)</td><td>-10.376<br>(12.670)</td><td>-7.695<br>(12.929)</td><td>-5.663<br>(13.112)</td></tr><tr><td>Time in gardens</td><td>-10.074<br>(6.919)</td><td>-10.570<br>(7.098)</td><td>-10.275<br>(7.057)</td><td>-10.033<br>(6.918)</td><td>-9.730<br>(6.910)</td></tr><tr><td>Time selling in other village</td><td>8.705*<br>(4.591)</td><td>8.723*<br>(4.514)</td><td>8.589*<br>(4.496)</td><td>8.732*<br>(4.466)</td><td>9.046**<br>(4.549)</td></tr><tr><td>Female child</td><td>-9.693<br>(11.234)</td><td>-9.403<br>(10.994)</td><td>-10.033<br>(11.207)</td><td>-7.509<br>(11.213)</td><td>-6.032<br>(11.332)</td></tr><tr><td>lnmother's age</td><td>30.810**<br>(12.862)</td><td>30.586**<br>(12.672)</td><td>30.903**<br>(12.938)</td><td>29.198**<br>(12.711)</td><td>28.647**<br>(12.551)</td></tr><tr><td>lnchild's age</td><td>21.214<br>(34.335)</td><td>20.862<br>(34.435)</td><td>21.487<br>(34.118)</td><td>24.468<br>(33.107)</td><td>23.418<br>(33.780)</td></tr><tr><td>Child's BMI</td><td>-0.920<br>(3.436)</td><td>-0.644<br>(3.392)</td><td>-0.913<br>(3.432)</td><td>-1.673<br>(3.313)</td><td>-1.303<br>(3.312)</td></tr><tr><td># Children in HH</td><td>0.852<br>(3.450)</td><td>0.827<br>(3.345)</td><td>0.922<br>(3.422)</td><td>0.272<br>(3.335)</td><td>-0.001<br>(3.348)</td></tr><tr><td>Spouse not biofather</td><td>32.504**<br>(15.099)</td><td>30.763**<br>(14.742)</td><td>32.262**<br>(14.979)</td><td>36.190**<br>(15.126)</td><td>35.436**<br>(15.191)</td></tr><tr><td>Religiosity</td><td>3.154<br>(4.428)</td><td>2.564<br>(4.269)</td><td>3.245<br>(4.394)</td><td>3.340<br>(4.381)</td><td>2.297<br>(4.372)</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>378</td><td>378</td><td>378</td><td>378</td><td>378</td></tr><tr><td>R<sup>2</sup></td><td>0.465</td><td>0.468</td><td>0.465</td><td>0.476</td><td>0.480</td></tr><tr><td>Mean DV</td><td>206.67</td><td>206.67</td><td>206.67</td><td>206.67</td><td>206.67</td></tr><tr><td>SD DV</td><td>80.87</td><td>80.87</td><td>80.87</td><td>80.87</td><td>80.87</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a child recording. Care variables are indicators for whether the child receives care at the frequency indicated. All estimates include village fixed effects. All controls displayed. Support variables and time working in gardens and selling goods normalized to mean zero, standard deviation one. Standard errors in parentheses, clustered by child. Missing observations imputed for control variables and all estimates include indicator variables for missing observations of control variables. All estimates weighted by the duration of the recording.</footnote>
<table><caption>Table B13: Robustness: Allomaterial care and child vocalizations, controlling for mother stress</caption><thead><tr><th></th><th>(1)</th><th>(2)</th><th>(3)</th><th>(4)</th><th>(5)</th><th>(6)</th><th>(7)</th><th>(8)</th><th>(9)</th></tr></thead><tbody><tr><td colspan="10"><strong>Panel A: Vocalizations per hour – Cortisol</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>0.004<br>(8.289)</td><td>-2.889<br>(10.273)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>-1.560<br>(9.589)</td></tr><tr><td>Care: Father (daily)</td><td></td><td></td><td>-6.231<br>(14.486)</td><td>-1.621<br>(17.708)</td><td></td><td></td><td></td><td></td><td>1.125<br>(16.209)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td></td><td></td><td>0.484<br>(16.057)</td><td>-3.153<br>(15.531)</td><td></td><td></td><td>-2.036<br>(18.088)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>28.369<br>(20.223)</td><td>56.840***<br>(19.892)</td><td>56.661***<br>(20.356)</td></tr><tr><td>Ln(Mother's cortisol)</td><td>-18.271*<br>(10.606)</td><td>-14.682<br>(12.286)</td><td>-17.575<br>(10.925)</td><td>-14.308<br>(13.005)</td><td>-18.262*<br>(10.582)</td><td>-14.397<br>(12.479)</td><td>-18.499*<br>(10.402)</td><td>-15.184<br>(11.460)</td><td>-15.356<br>(11.880)</td></tr><tr><td>R<sup>2</sup></td><td>0.418</td><td>0.481</td><td>0.419</td><td>0.480</td><td>0.418</td><td>0.480</td><td>0.428</td><td>0.514</td><td>0.514</td></tr><tr><td colspan="10"><strong>Panel B: Vocalizations per hour – Cortisone</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-1.373<br>(7.169)</td><td>-4.685<br>(9.578)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>-3.450<br>(9.061)</td></tr><tr><td>Care: Father (daily)</td><td></td><td></td><td>-0.285<br>(14.411)</td><td>2.384<br>(17.108)</td><td></td><td></td><td></td><td></td><td>5.409<br>(16.145)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td></td><td></td><td>2.806<br>(15.807)</td><td>1.889<br>(15.508)</td><td></td><td></td><td>2.663<br>(18.346)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>30.951<br>(19.087)</td><td>54.011***<br>(18.473)</td><td>53.794***<br>(18.943)</td></tr><tr><td>Ln(Mother's cortisone)</td><td>-38.227***<br>(12.177)</td><td>-31.143**<br>(13.381)</td><td>-38.107***<br>(13.197)</td><td>-30.815**<br>(13.745)</td><td>-38.155***<br>(12.185)</td><td>-30.613**<br>(13.522)</td><td>-38.968***<br>(11.635)</td><td>-29.380**<br>(12.000)</td><td>-30.609**<br>(12.454)</td></tr><tr><td>Extended controls:</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>N</td><td>Y</td><td>Y</td></tr><tr><td>Village FE:</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td><td>Y</td></tr><tr><td>Observations</td><td>196</td><td>196</td><td>196</td><td>196</td><td>196</td><td>196</td><td>196</td><td>196</td><td>196</td></tr><tr><td>R<sup>2</sup></td><td>0.458</td><td>0.505</td><td>0.458</td><td>0.504</td><td>0.458</td><td>0.504</td><td>0.469</td><td>0.534</td><td>0.535</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a child recording, restricted to the sample of children for whom cortisol and cortisone measures are available for the mother. Care variables are indicators for whether the child receives care at the frequency indicated. All estimates include village fixed effects, and control the child's ln(age), gender, and mother's ln(age). Extended controls includes: child BMI, whether the mother's spouse is the biological father of the child, total number of children in the household, and the following controls for the mother: cognitive ability, number of consumer durables owned, amount of time spent working in the gardens, amount of time spent selling goods in another village, whether she has witnessed inter-village violence, religiosity, and the amount of various forms of support (i.e., small and large financial, help with production, emotional support, and attend the same church) that she receives from all individuals in her network. Support variables and time working in gardens and selling goods normalized to mean zero, standard deviation one. Standard errors in parentheses, clustered by child. Missing observations imputed for control variables and all estimates include indicator variables for missing observations of control variables. All estimates weighted by the duration of the recording.</footnote>