<table><caption>Table B14: Allomaterial care and adult female 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>1.984<br>(5.343)</td><td></td><td></td><td></td><td>2.527<br>(5.337)</td></tr><tr><td>Care: Father (daily)</td><td></td><td>-4.381<br>(10.282)</td><td></td><td></td><td>-4.302<br>(10.338)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>9.241<br>(29.602)</td><td></td><td>12.174<br>(28.901)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-5.320<br>(15.042)</td><td>-5.296<br>(15.037)</td></tr><tr><td>R<sup>2</sup></td><td>0.441</td><td>0.441</td><td>0.442</td><td>0.441</td><td>0.443</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>7.112<br>(5.360)</td><td></td><td></td><td></td><td>7.742<br>(5.445)</td></tr><tr><td>Care: Father (daily)</td><td></td><td>-12.303<br>(10.568)</td><td></td><td></td><td>-13.781<br>(10.641)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-3.940<br>(28.739)</td><td></td><td>-3.106<br>(28.579)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-0.751<br>(14.982)</td><td>-0.272<br>(15.360)</td></tr><tr><td>Mother's cognitive ability</td><td>-0.252<br>(0.871)</td><td>-0.170<br>(0.869)</td><td>-0.185<br>(0.870)</td><td>-0.165<br>(0.869)</td><td>-0.280<br>(0.872)</td></tr><tr><td>Consumer durables</td><td>3.236<br>(3.540)</td><td>2.980<br>(3.589)</td><td>2.559<br>(3.523)</td><td>2.486<br>(3.530)</td><td>3.921<br>(3.645)</td></tr><tr><td>Emotional support</td><td>-6.760<br>(6.301)</td><td>-5.760<br>(6.551)</td><td>-6.925<br>(6.186)</td><td>-6.990<br>(6.296)</td><td>-5.204<br>(6.453)</td></tr><tr><td>Small financial support</td><td>-5.632<br>(6.220)</td><td>-6.668<br>(6.403)</td><td>-4.949<br>(6.185)</td><td>-4.903<br>(6.282)</td><td>-7.863<br>(6.596)</td></tr><tr><td>Large financial support</td><td>-6.209<br>(6.113)</td><td>-5.719<br>(6.153)</td><td>-5.649<br>(6.167)</td><td>-5.508<br>(6.294)</td><td>-6.530<br>(6.237)</td></tr><tr><td>Production support</td><td>12.739*<br>(7.484)</td><td>13.560*<br>(7.283)</td><td>12.416<br>(7.656)</td><td>12.257*<br>(7.409)</td><td>14.485*<br>(7.562)</td></tr><tr><td>Church congregants</td><td>-1.729<br>(7.998)</td><td>-3.240<br>(7.785)</td><td>-2.779<br>(7.618)</td><td>-2.915<br>(7.822)</td><td>-1.748<br>(7.609)</td></tr><tr><td>Witness violence (0/1)</td><td>16.407<br>(11.533)</td><td>15.762<br>(11.225)</td><td>14.889<br>(10.986)</td><td>14.625<br>(11.333)</td><td>17.890<br>(11.908)</td></tr><tr><td>Time in gardens</td><td>-8.957<br>(6.638)</td><td>-10.312<br>(6.687)</td><td>-9.923<br>(6.631)</td><td>-10.105<br>(6.629)</td><td>-8.961<br>(6.735)</td></tr><tr><td>Time selling in other village</td><td>0.846<br>(4.563)</td><td>0.459<br>(4.526)</td><td>0.334<br>(4.545)</td><td>0.338<br>(4.532)</td><td>1.015<br>(4.608)</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>0.495</td><td>0.495</td><td>0.492</td><td>0.492</td><td>0.499</td></tr><tr><td>Mean DV</td><td>231.91</td><td>231.91</td><td>231.91</td><td>231.91</td><td>231.91</td></tr><tr><td>SD DV</td><td>82.36</td><td>82.36</td><td>82.36</td><td>82.36</td><td>82.36</td></tr></tbody></table>

<footnote>All specifications identical to Table 3 but using adult female vocalizations as an outcome. * 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.</footnote>
<table><caption>Table B15: Allomaterial care and adult male 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>0.262<br>(4.471)</td><td></td><td></td><td>-0.723<br>(4.468)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-5.297<br>(7.063)</td><td></td><td>-4.812<br>(7.196)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-19.119<br>(15.082)</td><td>-19.107<br>(15.261)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-2.313<br>(9.248)</td><td>-0.566<br>(9.588)</td></tr><tr><td>R<sup>2</sup></td><td>0.382</td><td>0.383</td><td>0.388</td><td>0.382</td><td>0.389</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>3.039<br>(4.395)</td><td></td><td></td><td>2.789<br>(4.338)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-6.318<br>(7.837)</td><td></td><td>-7.618<br>(7.860)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-29.897*<br>(17.293)</td><td>-29.848*<br>(17.904)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-1.306<br>(10.302)</td><td>-0.701<br>(10.460)</td></tr><tr><td>Mother's cognitive ability</td><td>0.063<br>(0.567)</td><td>0.098<br>(0.570)</td><td>-0.051<br>(0.565)</td><td>0.100<br>(0.566)</td><td>-0.087<br>(0.570)</td></tr><tr><td>Consumer durables</td><td>4.338*<br>(2.263)</td><td>4.272*<br>(2.322)</td><td>4.597**<br>(2.237)</td><td>4.022*<br>(2.268)</td><td>5.202**<br>(2.315)</td></tr><tr><td>Emotional support</td><td>-2.544<br>(4.292)</td><td>-2.006<br>(4.416)</td><td>-1.822<br>(4.133)</td><td>-2.582<br>(4.296)</td><td>-0.884<br>(4.276)</td></tr><tr><td>Small financial support</td><td>3.109<br>(4.069)</td><td>2.508<br>(4.116)</td><td>2.608<br>(4.000)</td><td>3.335<br>(4.219)</td><td>1.104<br>(4.150)</td></tr><tr><td>Large financial support</td><td>0.732<br>(4.423)</td><td>0.927<br>(4.361)</td><td>0.228<br>(4.260)</td><td>1.081<br>(4.408)</td><td>-0.103<br>(4.329)</td></tr><tr><td>Production support</td><td>-1.262<br>(5.232)</td><td>-0.795<br>(5.213)</td><td>0.097<br>(5.279)</td><td>-1.403<br>(5.326)</td><td>1.187<br>(5.438)</td></tr><tr><td>Church congregants</td><td>2.262<br>(4.781)</td><td>1.592<br>(4.760)</td><td>3.188<br>(4.641)</td><td>1.829<br>(4.753)</td><td>3.559<br>(4.720)</td></tr><tr><td>Witness violence (0/1)</td><td>8.681<br>(7.985)</td><td>8.498<br>(8.329)</td><td>9.451<br>(8.100)</td><td>7.832<br>(8.145)</td><td>10.722<br>(8.002)</td></tr><tr><td>Time in gardens</td><td>5.160<br>(4.924)</td><td>4.562<br>(4.810)</td><td>6.001<br>(4.643)</td><td>4.660<br>(4.856)</td><td>6.307<br>(4.766)</td></tr><tr><td>Time selling in other village</td><td>4.062<br>(3.081)</td><td>3.906<br>(3.075)</td><td>3.792<br>(3.092)</td><td>3.840<br>(3.068)</td><td>4.059<br>(3.125)</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>0.413</td><td>0.413</td><td>0.423</td><td>0.411</td><td>0.427</td></tr><tr><td>Mean DV</td><td>109.35</td><td>109.35</td><td>109.35</td><td>109.35</td><td>109.35</td></tr><tr><td>SD DV</td><td>48.71</td><td>48.71</td><td>48.71</td><td>48.71</td><td>48.71</td></tr></tbody></table>

<footnote>All specifications identical to Table 3 but using adult male vocalizations as an outcome. * 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.</footnote>
<table><caption>Table B16: Allomaterial care and child vocalizations: robustness to winsorizing</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>-0.367<br>(5.838)</td><td></td><td></td><td></td><td>0.484<br>(6.130)</td></tr><tr><td>Care: Father (daily)</td><td></td><td>-11.278<br>(10.388)</td><td></td><td></td><td>-12.485<br>(10.537)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>5.341<br>(18.496)</td><td></td><td>2.463<br>(20.073)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>23.358*<br>(13.310)</td><td>24.250*<br>(13.450)</td></tr><tr><td>R<sup>2</sup></td><td>0.437</td><td>0.440</td><td>0.437</td><td>0.444</td><td>0.448</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>2.060<br>(6.264)</td><td></td><td></td><td></td><td>3.320<br>(6.241)</td></tr><tr><td>Care: Father (daily)</td><td></td><td>-10.800<br>(10.587)</td><td></td><td></td><td>-10.192<br>(10.388)</td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>8.125<br>(19.279)</td><td></td><td>5.793<br>(20.452)</td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>34.674**<br>(14.581)</td><td>34.509**<br>(14.777)</td></tr><tr><td>Mother's cognitive ability</td><td>0.785<br>(0.955)</td><td>0.774<br>(0.940)</td><td>0.852<br>(0.943)</td><td>0.821<br>(0.926)</td><td>0.803<br>(0.936)</td></tr><tr><td>Consumer durables</td><td>1.851<br>(3.593)</td><td>1.981<br>(3.607)</td><td>1.442<br>(3.542)</td><td>1.791<br>(3.476)</td><td>2.361<br>(3.527)</td></tr><tr><td>Emotional support</td><td>-8.713<br>(6.558)</td><td>-7.844<br>(6.682)</td><td>-9.118<br>(6.745)</td><td>-10.665+<br>(6.823)</td><td>-9.687<br>(7.022)</td></tr><tr><td>Small financial support</td><td>1.205<br>(8.061)</td><td>-0.409<br>(8.228)</td><td>1.625<br>(7.925)</td><td>4.916<br>(7.898)</td><td>2.970<br>(8.623)</td></tr><tr><td>Large financial support</td><td>-6.519<br>(6.348)</td><td>-6.668<br>(6.439)</td><td>-6.007<br>(6.365)</td><td>-7.760<br>(6.304)</td><td>-8.216<br>(6.237)</td></tr><tr><td>Production support</td><td>-7.668<br>(6.929)</td><td>-6.632<br>(6.824)</td><td>-8.271<br>(6.835)</td><td>-10.423+<br>(7.206)</td><td>-9.365<br>(7.140)</td></tr><tr><td>Church congregants</td><td>14.112*<br>(7.291)</td><td>13.682**<br>(6.920)</td><td>13.343*<br>(7.228)</td><td>11.242+<br>(6.963)</td><td>11.500+<br>(7.212)</td></tr><tr><td>Witness violence (0/1)</td><td>-15.484<br>(13.359)</td><td>-15.224<br>(12.978)</td><td>-16.429<br>(13.065)</td><td>-13.218<br>(13.305)</td><td>-12.360<br>(13.505)</td></tr><tr><td>Time in gardens</td><td>-7.790<br>(7.179)</td><td>-8.308<br>(7.379)</td><td>-8.486<br>(7.247)</td><td>-8.160<br>(7.234)</td><td>-7.863<br>(7.088)</td></tr><tr><td>Time selling in other village</td><td>6.769+<br>(4.612)</td><td>6.749+<br>(4.517)</td><td>6.647+<br>(4.527)</td><td>6.762+<br>(4.446)</td><td>7.075+<br>(4.519)</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>341</td><td>341</td><td>341</td><td>341</td><td>341</td></tr><tr><td>R<sup>2</sup></td><td>0.495</td><td>0.497</td><td>0.495</td><td>0.509</td><td>0.512</td></tr><tr><td>Mean DV</td><td>209.98</td><td>209.98</td><td>209.98</td><td>209.98</td><td>209.98</td></tr><tr><td>SD DV</td><td>79.37</td><td>79.37</td><td>79.37</td><td>79.37</td><td>79.37</td></tr></tbody></table>

<footnote>+ p<0.15, * p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a child recording. Sample excludes bottom and top 5th percentiles of recording lengths. 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.</footnote>
<table><caption>Table B17: Robustness: Allomaterial care and child stress</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: ln(Cortisol) – Basic controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-0.047<br>(0.171)</td><td></td><td></td><td>-0.092<br>(0.165)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-0.601*<br>(0.336)</td><td></td><td>-0.567*<br>(0.328)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-0.172<br>(0.378)</td><td>-0.325<br>(0.408)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-0.666**<br>(0.271)</td><td>-0.614**<br>(0.260)</td></tr><tr><td>R<sup>2</sup></td><td>0.327</td><td>0.364</td><td>0.327</td><td>0.353</td><td>0.389</td></tr><tr><td colspan="6"><strong>Panel B: ln(Cortisol) – Extended controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-0.123<br>(0.111)</td><td></td><td></td><td>-0.107<br>(0.120)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>-0.404<br>(0.266)</td><td></td><td>-0.421<br>(0.283)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>-0.261<br>(0.266)</td><td>-0.382<br>(0.293)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-0.158<br>(0.266)</td><td>-0.234<br>(0.293)</td></tr><tr><td>Ln(Mother's cortisol)</td><td>0.377*<br>(0.200)</td><td>0.419**<br>(0.187)</td><td>0.376*<br>(0.199)</td><td>0.382*<br>(0.199)</td><td>0.426**<br>(0.198)</td></tr><tr><td>R<sup>2</sup></td><td>0.551</td><td>0.560</td><td>0.549</td><td>0.549</td><td>0.568</td></tr><tr><td colspan="6"><strong>Panel C: ln(Cortisone) – Basic controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-0.032<br>(0.128)</td><td></td><td></td><td>-0.043<br>(0.128)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>0.117<br>(0.167)</td><td></td><td>0.153<br>(0.168)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>0.162<br>(0.340)</td><td>0.159<br>(0.348)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-0.317**<br>(0.137)</td><td>-0.347**<br>(0.147)</td></tr><tr><td>R<sup>2</sup></td><td>0.368</td><td>0.371</td><td>0.369</td><td>0.385</td><td>0.396</td></tr><tr><td colspan="6"><strong>Panel D: ln(Cortisone) – Extended controls</strong></td></tr><tr><td>Care: Mother (Ln(Hours/week))</td><td>-0.051<br>(0.114)</td><td></td><td></td><td>-0.077<br>(0.114)</td><td></td></tr><tr><td>Care: Father (daily)</td><td></td><td>0.300*<br>(0.155)</td><td></td><td>0.331*<br>(0.171)</td><td></td></tr><tr><td>Care: Other relatives of child (weekly or more)</td><td></td><td></td><td>0.177<br>(0.327)</td><td>0.228<br>(0.342)</td><td></td></tr><tr><td>Care: Non-relatives (weekly or more)</td><td></td><td></td><td></td><td>-0.150<br>(0.201)</td><td>-0.119<br>(0.193)</td></tr><tr><td>Ln(Mother's cortisone)</td><td>0.157*<br>(0.091)</td><td>0.125<br>(0.094)</td><td>0.153*<br>(0.089)</td><td>0.161*<br>(0.093)</td><td>0.112<br>(0.090)</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>103</td><td>103</td><td>103</td><td>103</td><td>103</td></tr><tr><td>R<sup>2</sup></td><td>0.585</td><td>0.603</td><td>0.586</td><td>0.587</td><td>0.614</td></tr></tbody></table>

<footnote>* p<0.10, ** p<0.05, *** p<0.01. Unit of observation is a child. Care variables are indicators for whether the child receives care at the frequency indicated. All estimates include village fixed effects, and control for the child's ln(age), gender, and mother's ln(age). Panels B and D include 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. Standard errors in parentheses clustered at the village level. Missing observations imputed for control variables and all estimates include indicator variables for missing observations of control variables.</footnote>
# C Empirical specifications for summary figures and child-level regressions

## Summary figures for help with child care and dictator game giving

To construct Figure 2, we limit the sample to participants with children (N=631). In panel (a), we calculate the average amount of reported help with child care from each individual in the participant's network (spouse, mother, father, sister, brother, mother-in-law, father-in-law, friend, neighbor). We conduct t-tests for differences in means between mothers' and fathers' reported help with child care, separately for each individual in their network, and report stars, which correspond to p-values, above the bars.

In panel (b) of Figure 2 we calculate the average share sent in the dictator game, both anonymously (altruism) and non-anonymously (reciprocity), to each individual in the participant's network, including strangers. We conduct t-tests for differences in altruism vs. reciprocity, for mothers and fathers separately, and report stars, which correspond to p-values, above the bars.

## Regressions for child socio-cognitive and socio-emotional benefits

The subset of 183 married couples with a small child, for whom we surveyed both the wife and the husband, constitutes our analytical sample. In a few cases in which the parents had more than one child in the target age range, we collected information on the additional children, for a total of 197 children, which constitutes our sample of child vocalizations. Because each child had 2 USB devices, most children have 2 observations of vocalizations. There are 10 children for whom only 1 recording is available, therefore the total sample of child recordings is N=384.

We estimate the following equation at the level of a child-recording (cr), and include controls for the mother (m) and the amount of child care provided by various relatives and non-relatives (k):

$$y_{cr} = \alpha + \sum_{k=1}^{4} \beta_k \text{Care}_{kc} + X'_{cm} \Gamma + \mu_v + \varepsilon_{cr} \quad (6)$$

where $y_{cr}$ is the number of vocalizations per hour by child c on USB recording device r. We first introduce the amount of care from various relatives and non-relatives ($Care_{kc}$) separately to avoid potential issues with multicollinearity across care from different people, and then together. In all specifications, we control for the child's ln(age) and gender, as well as the mother's ln(age) in $X_{cm}$. We then include an extended set of controls in $X_{cm}$, as described in the main text: chid BMI, total number of children in the household, whether the mother's spouse is the child's biological father, the usual set of mother-level characteristics: proxy for cognitive ability, wealth, social, emotional, productive, and economic support, as well as presence of relatives in the village, time spent in gardens and participation in market, and conflict exposure. We include village fixed effects ($\mu_v$) to account for unobservable factors that influence care and child speech at the village level. We weight all regressions by the duration of the recording and cluster standard errors by child.

For logistical reasons, we only collected hair samples in Western Province.<fnref n="51" /> The

<footnote n="51">⁵¹Each team had to carry all their food and equipment. In Western Province, but not in Choiseul, the</footnote>
sample of child-mother pairs for whom cortisol and cortisone were measured consists of N=102 children. We estimate the following equation at the level of the child (c), and include controls for the mother (m) and the amount of child care provided by various relatives and non-relatives (k):

$$y_c = \alpha + \sum_{k=1}^{4} \beta_k \text{Care}_{kc} + X'_{cm} \Gamma + \mu_v + \varepsilon_c \quad (7)$$

where $y_c$ is the natural log of the child's hormone level and $Care_{kc}$ is the amount of care provided by various relatives and non-relatives, including: (i) the mother (log of hours per week); (ii) biological father (indicator equal to 1 if care provided on a daily basis); (iii) other relatives of the child, including the maternal and paternal grandparents, as well as the brother and sister of the mother (indicator equal to 1 if care provided on a weekly or more frequent basis); and (iv) non-relatives (indicator equal to 1 if care provided on a weekly or more frequent basis). We first introduce the amount of care from various relatives and non-relatives separately to avoid potential issues with multicollinearity across care from different people, and then together. In all specifications, we control for the child's ln(age) and gender, as well as the mother's ln(age) in $X_{cm}$, and then include the set of extended controls described above, as well as mother's stress. We include village fixed effects to account for unobservable factors at the village level that influence both child care and child stress. We cluster standard errors at the village level.

<footnote>teams were able to go back to a central location where they could store the hair samples.</footnote>
# D Data Appendix

<table><caption>Table D1: Variable Descriptions</caption><thead><tr><th>Variable Name</th><th>Description</th></tr></thead><tbody><tr><td><em>Solomon Islands Sample</em></td><td></td></tr><tr><td>Share sent</td><td>The share of the endowment (SI$40) sent in the dictator game. Senders could give $0, $10, $20, $30, or $40, such that the variable takes values 0, 0.25, 0.5, 0.75, or 1.</td></tr><tr><td>Child care</td><td>The amount of help with child care that the receiver gives to the participant. Coded 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. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Child care from relatives</td><td>The sum of each <em>child care</em> variable for the following receivers: mother, father, sister, brother. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Child care from non-relatives</td><td>The sum of each <em>child care</em> variable for the following receivers: friends and neighbors. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Same village</td><td>Binary variable equal to one if the receiver is a stranger in the same village, zero otherwise.</td></tr><tr><td>Reciprocity</td><td>Binary variable equal to one if the <em>share sent</em> was given under the non-anonymous dictator game condition, zero otherwise.</td></tr><tr><td>Emotional support</td><td>The amount of emotional support that the receiver gives to the participant. Coded 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. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Small financial support</td><td>A binary variable equal to one if the participant reports that they could ask the receiver for small financial support when in need, zero otherwise.</td></tr></tbody></table>
<table><tr><td>Large financial support</td><td>A binary variable equal to one if the participant reports that they could ask the receiver for large financial support when in need, zero otherwise.</td></tr><tr><td>Production support</td><td>The amount of help that the receiver gives to the participant in their gardens and with fishing. Coded 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. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Attend same church</td><td>A binary variable equal to one if the receiver attends the same church congregation as the participant, zero otherwise.</td></tr><tr><td>Cognitive ability</td><td>Number of correct answers (out of 24) to Raven's-like matrix puzzles.</td></tr><tr><td>Child vocalizations</td><td>Number of vocalizations per hour by the recorded child.</td></tr><tr><td>Cortisol (pg/mg)</td><td>Picograms per milligram of cortisol measured by hair sample.</td></tr><tr><td>Cortisone (pg/mg)</td><td>Picograms per milligram of cortisone measured by hair sample.</td></tr><tr><td>Time in gardens</td><td>The frequency at which the participant works in their gardens. Coded 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. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Time selling in other village</td><td>The frequency at which the participant sells goods in villages other than their own. Coded as: (0) never, (1) once a year or less, (2) once a month, (3) once a week or more. Normalized to mean zero, standard deviation one.</td></tr><tr><td>Witness violence</td><td>Answer to the question: "Have you ever witnessed organized violence (i.e. in a group of more than 2 people) or warfare with people from another village?". Coded as (0) No, (1) Yes.</td></tr></table>
**Religiosity**
The frequency at which the participant engages in religious activities, e.g. praying, attending or preparing mass, preparing food for religious ceremonies. Coded 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.

**Consumer durables**
The sum of dummies capturing whether the respondent owns: a mobile phone, a FM radio, an iron roof, a solar light, a water tank, a toilet, a stove, an outboard motor.

**Number of relatives in the village**
Constructed from a roster of family members living in the same village.

### Standard Cross-Cultural Sample (SCCS)

**Allomaterial care**
The role of non-maternal relations in infancy (v51). Coded from 1 to 6, where 1 is “almost exclusively mother”, 5 is care from mothers is “minor but significant”, and 6 is mother has minimal role “except nursing”.

**Trust**
The importance of inculcating trust in children (v335). Originally coded in Barry et al. (1976) and “refers to confidence in social relationships, especially toward community members outside the family”. Coded on a scale of 0 to 10, where 0 is “no strong inculcation” and 10 is “extremely strong inculcation”.

**Honesty**
The importance of inculcating honesty in the society (v336). Originally coded in Barry et al. (1976) and “refers to desire and strong approval for truthfulness under all circumstances” in the society. Coded on a scale of 0 to 10, where 0 is “no strong inculcation” and 10 is “extremely strong inculcation”.

**Population density**
(v64). Coded on a scale of 1 to 7, where 1 is “less than 1 person per 5 sq. mile” and 7 is “over 500 persons per sq. mile”.

**Complexity settlements**
(v705: “Settlement type”). Coded on a scale of 1 to 8, where 1 is “fully migratory or nomadic bands” and 8 is “complex settlements surrounded by homes”.

**Size of communities**
(v235: “Mean Size of Local Communities”). Coded on a scale of 1 to 8, where 1 is “fewer than 50” and 8 is “one or more cities of more than 50,000”.
<table><tr><td>Witchcraft</td><td>Presence of witchcraft in the society (v656). Coded as: (1) absence of such a cause, (2) minor or relatively important cause, (3) an important auxiliary cause, and (4) predominant cause recognized by the society.</td></tr><tr><td>Rainfall</td><td>Log mean yearly average rainfall (v1913).</td></tr><tr><td>Temperature</td><td>Log mean annual temperature (v186).</td></tr><tr><td>Longitude</td><td>Longitude in degrees (longitude).</td></tr><tr><td>Latitude</td><td>Latitude in degrees (latitude).</td></tr><tr><td>Altitude</td><td>Altitude in meters (v183).</td></tr><tr><td>Number of dry months</td><td>Number of dry months (v196).</td></tr><tr><td>Number of frost months</td><td>Number of frost months (v199).</td></tr><tr><td>Date of observation</td><td>Focal year for the SCCS society (focyear).</td></tr><tr><td>Region</td><td>Dummy variable indicating: Africa, Circum-Mediterranean, East Eurasia, Insular Pacific, North America, or South America (v200).</td></tr><tr><td>Publication date</td><td>Date of publication of the study from which the ethno-graphic information is derived (v802).</td></tr><tr><td>Belief in moralizing gods</td><td>Presence of a belief in moralizing gods who intervene in human affairs (v238). Coded as: (1) absent or not reported, (2) present but not active in human affairs, (3) present and active in human affairs, (4) present, active, and specifically supporting morality.</td></tr></table>
E Experimental Instructions

SOLOMON ISLANDS PROJECT
DICTATOR GAME EXPERIMENTAL INSTRUCTIONS
ENUMERATOR SCRIPT

May 1, 2019