bluuebunny/crossref_metadata_2025 huggingface dataset:
The Matthew Effect: Evolutionary Implications
Authors: Sloman Leon , Dunham David W.
Published: July 2015

This article suggests that, in prehistoric man, the results of competition magnified the effect of small genetic differences between competing individuals, thereby increasing the differential in their relative reproductive success (difference amplification). This had the effect of accelerating the evolution of early man. The differential effect of success and failure on competing individuals led to “difference amplification”. These mechanisms can still be observed today. This model is relevant to psychotherapy with depressed clients.
Cheaters Are Looked at Longer and Remembered Better than Cooperators in Social Exchange Situations
Authors: Chiappe Dan , Brown Adam , Dow Brian
Published: July 2015

What information is most salient during social exchange? Our studies assess the relative importance of cheaters and cooperators and whether their importance is affected by amount of resources involved in the exchange. In Experiment 1, participants categorized individuals as cheaters, cooperators, or neither, and rated how important they are to remember using a 7-point scale. In Experiment 2, participants categorized individuals, and then looked at their photos. This was followed by tests of face recognition, and memory for social contract status. Experiment 1 found cheaters were rated more important to remember than cooperators and more so when a greater amount of resources was involved. Experiment 2 found cheaters were looked at longer and people had better memory for their faces and were more likely to remember their social contract status. This suggests the mind evolved to remember information most pertinent in social contract situations.
Which Infidelity Type Makes You More Jealous? Decision Strategies in a Forced-Choice between Sexual and Emotional Infidelity
Authors: Schützwohl Achim
Published: July 2015

This study tested the prediction derived from the evolutionary psychological analysis of jealousy that men and women selecting the adaptively primary infidelity type (i.e., female sexual and male emotional infidelity, respectively) in a forced-choice response format need to engage in less elaborate decision strategies than men and women selecting the adaptively secondary infidelity type (i.e., male sexual and female emotional infidelity, respectively). Unknown to the participants, decision times were registered as an index of the elaborateness of their decision strategies. The results clearly support the prediction. Implications and limitations of the present findings are discussed.
The Heroine with a Thousand Faces: Universal Trends in the Characterization of Female Folk Tale Protagonists
Authors: Gottschall Jonathan
Published: July 2015

Literary scholars and psychologists have long remarked striking similarities in the depiction of male heroes in the world's folk tale traditions. The best-known attempt to document and explain these similarities is Joseph Campbell's The Hero with a Thousand Faces (1936). Campbell's work differs in detail from other prominent attempts to define universal features of heroes, however its grand thesis is much the same: while the details of heroes “faces” may change as the investigator crosses geographical, ethnic, cultural and chronological borders, certain details of the hero's life and challenges are everywhere the same. However, in contrast to the many determined efforts to generalize about heroes, scholars have expended little effort generalizing about cross-cultural features of heroines. The present article, based on a quantitative content analysis of folk tales from 48 culture areas around the world, represents the first systematic attempt to identify and explain cross-cultural trends in the characterization of heroines. This study was designed to improve substantially on previous attempts to define literary universals by drawing upon theory and methods used by human scientists to fruitfully explore and explain human universals.
An Environmental Approach to Positive Emotion: Flowers
Authors: Haviland-Jones Jeannette , Rosario Holly Hale , Wilson Patricia , McGuire Terry R.
Published: July 2015

For more than 5000 years, people have cultivated flowers although there is no known reward for this costly behavior. In three different studies we show that flowers are a powerful positive emotion “inducer”. In Study 1, flowers, upon presentation to women, always elicited the Duchenne or true smile. Women who received flowers reported more positive moods 3 days later. In Study 2, a flower given to men or women in an elevator elicited more positive social behavior than other stimuli. In Study 3, flowers presented to elderly participants (55+ age) elicited positive mood reports and improved episodic memory. Flowers have immediate and long-term effects on emotional reactions, mood, social behaviors and even memory for both males and females. There is little existing theory in any discipline that explains these findings. We suggest that cultivated flowers are rewarding because they have evolved to rapidly induce positive emotion in humans, just as other plants have evolved to induce varying behavioral responses in a wide variety of species leading to the dispersal or propagation of the plants.
Dennett, Darwin, and Skinner Crows
Authors: Blommaert Frans , Janssen Ruud
Published: July 2015

The central theme of this paper is the scientific viewpoint taken for understanding behavioral processes. Two classical viewpoints are formulated by Dennett (the intentional stance) and Tinbergen (Tinbergen's four questions). In this paper we argue that the two different viewpoints are linked to the two different processes that underlie complex behavior, namely, the instruction process and the selection process. To zoom in on the similarities and differences between these processes, we model whelk dropping behavior of Northwestern crows as observed by Zach (1978, 1979) from the two different viewpoints: (1) with crows that possess intentional faculties (called Dennett crows), and (2) with crows that possess selectional faculties. The latter type of crows is further divided into a population that is able to adapt over generations only by natural selection (Darwin crows), and a population that, apart from natural selection, is also able to adapt using operant learning (Skinner crows). Salient outcomes are that these two populations need markedly different times to adapt to changes in the environment, and that operant learning needs a value system that is an internal equivalent of the fitness criterion. In conclusion, we propose that understanding behavior should start at a meta-level with identifying whether the nature of the behavioral process under study is intentional or selectional.
Common Ground for Spatial Cognition? A Behavioral and fMRI Study of Sex Differences in Mental Rotation and Spatial Working Memory
Authors: Levin Sarah L. , Mohamed Feroze B. , Platek Steven M.
Published: July 2015

Sex differences in spatial cognition are well documented; males typically outperform females on tasks dealing with mental rotation and spatial navigation, while females tend to outperform males on tasks dealing with object location, relational object location memory, or spatial working memory. Here we investigated both behavioral and neural sex differences in sex-specific spatial abilities. In Experiment 1, sixty-six (30 males, 36 females) participants completed computerized mental rotation (MR) and spatial working memory (SWM) tasks. In Experiment 2, twelve (6 males, 6 females) participants were given slightly modified versions of the same tasks during functional magnetic resonance imaging (fMRI). In both experiments, males outperformed females on the MR task, but no behavioral sex difference was observed on the SWM task. Males showed more activation in left parahippocampal gyrus, right medial frontal gyrus, inferior parietal lobe, inferior frontal gyrus in the MR task. Females showed activation in the left parahippocampal gyrus only. For the study condition of the spatial working memory task, females showed activation in left inferior frontal gyrus, while males activated left inferior parietal and medial frontal areas. In the test conditions, females showed activation in the right inferior frontal gyrus, left middle temporal gyrus, and left parahippocampal gyrus. Males activated right medial frontal gyrus and inferior parietal lobe. Interestingly, similar regions – parahippocampal gyrus, inferior parietal lobe, and middle temporal gyrus - were found to be active when males solved mental rotation tasks and females solved spatial working memory tasks. Further, performance was modulated by activation in the parahippocampal gyrus and middle temporal gyrus for males and the middle temporal gyrus and inferior frontal gyrus for females. These data extend previous claims for sex differences in sex specific spatial cognitive abilities by demonstrating both behavioral and neural sex differences consistent with an evolutionary model, which suggests sexual selection may have favored sex-differences in such abilities and the neural substrates that sub-serve those processes.
The Effect of Vividness of Experience on Sex Differences in Jealousy
Authors: Strout Sarah L. , Laird James D. , Shafer Aaron , Thompson Nicholas S.
Published: July 2015

Doubt has been raised about the validity of results that appear to demonstrate sex differences in the type of infidelity that elicits jealousy. Two studies explored proposed methodological weaknesses of this research. The first study distinguished participants who had experienced infidelity and those who had only imagined infidelity. The study found the classic sex differences when participants were “forced” to choose which kind of infidelity would be most upsetting, and these differences were more pronounced among participants who were recalling the actual infidelity of a partner. The second study explored the impact of the relatively brief, perhaps cursory response that is commonly evoked by questionnaires versus a slower, more vivid imagining of the infidelity experience. The classic forced choice results were found, and the vivid imagining produced effects that are more powerful. The overall results suggest that participants who had experienced infidelity or vividly imagined infidelity showed greater sex differences, suggesting that the usual format (filling out a questionnaire) may not trigger the evolved mechanism for jealousy.
The Anti-Naturalistic Fallacy: Evolutionary Moral Psychology and the Insistence of Brute Facts
Authors: Walter Alex
Published: July 2015

The naturalistic fallacy and Hume's ‘law’ are frequently appealed to for the purpose of drawing limits around the scope of scientific inquiry into ethics and morality. These two objections are shown to be without force. Thus two highly influential obstacles are removed from naturalizing ethics. The relative merits of moral skepticism and moral realism are compared. Moral skepticism and some forms of moral realism are shown to make similar recommendations for developing a science of moral psychology.
A Laboratory Simulation of Parental Investment Decisions: The Role of Future Reproductive Opportunities and Quality of Offspring in Determining Levels of Parental Investment
Authors: Turner Stefanie L. , McAndrew Francis T.
Published: July 2015

Hagen's Defection Hypothesis (2002) predicts that a mother's age and the quality of her offspring are critical factors in determining her investment in her newborn. We tested this hypothesis using hamster races in which 113 college student participants received a hamster (“offspring”) and 10 poker chips (“resources”) to “invest” into the hamster based on information about the quality of the hamster and about the possibility of future races. Subjects invested the most in low quality offspring when they expected to run only one race and the least in low quality offspring when they expected more racing opportunities in the future. Offspring quality affected investment differently depending on the presence or absence of future investment opportunities and the sex of the subject. Overall, the results supported Hagen's model of parental investment and also suggest that parental investment may be explained by conscious as well as unconscious decision-making.
Hand of God, Mind of Man: Punishment and Cognition in the Evolution of Cooperation
Authors: Johnson Dominic , Bering Jesse
Published: July 2015

The evolution of human cooperation remains a puzzle because cooperation persists even in conditions that rule out mainstream explanations. We present a novel solution that links two recent theories. First, Johnson & Kruger (2004) suggested that ancestral cooperation was promoted because norm violations were deterred by the threat of supernatural punishment. However, this only works if individuals attribute negative life events (or a prospective afterlife) as intentionally caused by supernatural agents. A complementary cognitive mechanism is therefore required. Recently, Bering and Shackelford (2004) suggested precisely this. The evolution of “theory of mind” and, specifically, the “intentionality system” (a cognitive system devoted to making inferences about the epistemic contents and intentions of other minds), strongly favoured: (1) the selection of human psychological traits for monitoring and controlling the flow of social information within groups; and (2) attributions of life events to supernatural agency. We argue that natural selection favoured such attributions because, in a cognitively sophisticated social environment, a fear of supernatural punishment steered individuals away from costly social transgressions resulting from unrestrained, evolutionarily ancestral, selfish interest (acts which would rapidly become known to others, and thereby incur an increased probability and severity of punishment by group members). As long as the net costs of selfish actions from real-world punishment by group members exceeded the net costs of lost opportunities from self-imposed norm abiding, then god-fearing individuals would outcompete non-believers.
Who's Afraid of the Naturalistic Fallacy?
Authors: Curry Oliver
Published: July 2015

David Hume argued that values are the projections of natural human desires, and that moral values are the projections of desires that aim at the common good of society. Recent developments in game theory, evolutionary biology, animal behaviour and neuroscience explain why humans have such desires, and hence provide support for a Humean approach to moral psychology and moral philosophy. However, few philosophers have been willing to pursue this naturalistic approach to ethics for fear that it commits something called ‘the naturalistic fallacy’. This paper reviews several versions of the fallacy, and demonstrates that none of them present an obstacle to this updated, evolutionary version of Humean ethical naturalism.
Women More than Men Attend to Indicators of Good Character: Two Experimental Demonstrations
Authors: Bleske-Rechek April , Remiker Mark W. , Swanson Meghan R. , Zeug Nicole M.
Published: July 2015

Past research implicates adaptations in women to assess men's willingness to invest in offspring ( La Cerra, 1995 ). In two new studies, women's evaluations of an opposite-sex target as a long-term partner and short-term sex partner were negatively impacted by viewing that target ignore a baby in distress; this effect occurred for men in Study 1 only. Men's short-term sexual attraction to a female target was not affected by context. In Study 2, women responded similarly to a man vacuuming and to a man interacting with a happy baby. Neither sociosexual orientation nor sex-role beliefs moderated participants' sensitivity to targets' behavior. Women more than men appear to display a general sensitivity to an opposite-sex target's good character.
High-K Strategy Scale: A Measure of the High-K Independent Criterion of Fitness
Authors: Giosan Cezar
Published: July 2015

The present study aimed at testing whether factors documented in the literature as being indicators of a high-K reproductive strategy have effects on fitness in extant humans. A 26-item High-K Strategy Scale comprising these factors was developed and tested on 250 respondents. Items tapping into health and attractiveness, upward mobility, social capital and risks consideration, were included in the scale. As expected, the scale showed a significant correlation with perceived offspring quality and a weak, but significant association with actual number of children. The scale had a high reliability coefficient (Cronbach's Alpha = .92). Expected correlations were found between the scale and number of medical diagnoses, education, perceived social support, and number of previous marriages, strengthening the scale's construct validity. Implications of the results are discussed.
An Evolutionary Interpretation of Gift-Giving Behavior in Modern Norwegian Society
Authors: Mysterud Iver , Drevon Thomas , Slagsvold Tore
Published: July 2015

We have studied gift giving at Christmas among 50 graduate students in Norway. The students invested more the closer the coefficient of relatedness. However, partners ranked highest, which is natural for people at the start of their reproductive career. All students gave to their parents, siblings, and children, most gave to their grandparents, and only a third gave to some, but not all, of their genetic aunts/uncles. Twenty percent gave to first cousins, and none to second or third cousins. Similar patterns for gifts received were found. There were also sex differences (e.g. women had larger exchange networks than men), and birth order effects. Firstborns spent more on relatives than laterborns. However, middleborns gave more to their male friends than both firstborns and lastborns. We conclude that the results are consistent with theories of kin selection, reciprocity, sex differences and birth order effects.
Parental Investment and Resemblance: Replications, Refinements, and Revisions
Authors: Volk Anthony A. , Quinsey Vernon L.
Published: July 2015

Evolutionary theory predicts that men should be more concerned with issues of false paternity than women should be concerned with false maternity. In an earlier study ( Volk and Quinsey, 2002 ), we studied how infant cues of resemblance influenced adults' hypothetical adoption decisions. We found that self-perceived cues of resemblance were significantly more important in men's decisions than in women's. Since that study was published, conflicting results have been reported regarding a sex-difference in the importance of cues of resemblance for adoption preference. We therefore sought to replicate our findings in three new studies. In all three studies, we replicated the initial finding of a larger correlation between ratings of resemblance and ratings of adoption preference among men than among women. We also found a trend towards slightly higher global resemblance scores in younger children, suggesting that adults view infants as more anonymous and/or less uniquely distinctive than older children. However, there was wide variance in both the global resemblance and developmental changes in resemblance amongst the different child stimuli used.
Do Impressions of Health, Dominance, and Warmth Explain Why Masculine Faces are Preferred More in a Short-Term Mate?
Authors: Luevano Victor X. , Zebrowitz Leslie A.
Published: July 2015

Men high in facial masculinity are preferred more as a short-term partner (STP) than a long-term partner (LTP). We used a representative sample of natural faces to examine whether the greater preference for masculine-looking men as a STP could be explained by the fact that they look healthier, more dominant, or lower in warmth. None of these attributes explained the greater preference for facial masculinity in a STP. Rather, masculinity mediated the greater preference for healthy and dominant looking men as a STP. Women also preferred men who appeared high in warmth more as a LTP than a STP, an effect independent of facial masculinity, but mediated by facial expression. Our results suggest that women do not prefer masculine-looking men more as a STP than a LTP simply because they look healthier, more dominant, or less warm.
Getting Our History Right: Six Errors about Darwin and His Influence
Authors: Caton Hiram
Published: July 2015

The Darwin Exhibition created by the American Museum of Natural History is the centerpiece of the bicentennial of Darwin's birth. It opened in November 2005 and will circulate to a number of museums before terminating at the London Natural History Museum in February 2009. The Exhibition is also a major contributor to online instruction about evolution for schools. The quality of the Exhibition's narrative is accordingly of some significance. This paper argues that the narrative is the legendary history that dominates public opinion. The legend has been thoroughly disassembled by historical research over recent decades. My criticism is organized as six theses. (1) Publication of the Origin was not a sudden (“revolutionary”) interruption of Victorian society's confident belief in the traditional theological world-view. (2) The Origin did not “revolutionize” the biological sciences by removing the creationist premise or introducing new principles. (3) The Origin did not revolutionize Victorian public opinion. The public considered Darwin and Spencer to be teaching the same lesson, known today as “Social Darwinism”, which, though fashionable, never achieved dominance. (4) Many biologists expressed significant disagreements with Darwin's principles. (5) Darwin made little or no contribution to the renovation of theology. His public statements on Providence were inconsistent and the liberal reform of theology was well advanced by 1850. (6) The so-called “Darwinian revolution” was, at the public opinion level, the fashion of laissez-faire economic beliefs backed by Darwin and Spencer's inclusion of the living world in the economic paradigm.
Early Psychosocial Stress Predicts Extra-Pair Copulations
Authors: Koehler Nicole , Chisholm James S.
Published: July 2015

Cheating on a mate, known as an extra-pair copulation (EPC), is considered unacceptable by most individuals. Nonetheless many individuals engage in such risky behaviors. Because individuals with high, as opposed to low, levels of early psychosocial stress are more risk prone and more likely to engage in opportunistic matings, we predicted that individuals reporting EPCs, one of many types of opportunistic mating (e.g., one-night stand, consecutive short-term relationships etc), have higher levels of early psychosocial stress than those who do not. Two types of EPCs were examined: EPC-self (EPC-S), having sex with someone other than one's mate, and EPC-other (EPC-O), having sex with someone else's mate. In a sample of 229 women and 161 men, significantly higher levels of early psychosocial stress were found amongst those reporting an EPC-S than those reporting none, irrespective of EPC-Os. Furthermore, the more EPC-Ss men, but not women, reported the higher their early psychosocial stress. Early psychosocial stress was not associated with EPC-Os irrespective of EPC-Ss. Participants were also classified into one of four groups (no EPCs, EPC-O only, EPC-S only, or EPC-S&O) which significantly interacted with early psychosocial stress. Results are discussed from adaptationist and mechanist perspectives and why early psychosocial stress was higher in individuals reporting EPC-Ss irrespective of EPC-Os, but not EPC-Os irrespective of EPC-Ss, than those not reporting the EPC of interest.
Where Evolutionary Psychology Meets Cognitive Neuroscience: A Précis to Evolutionary Cognitive Neuroscience
Authors: Krill Austen L. , Platek Steven M. , Goetz Aaron T. , Shackelford Todd K.
Published: July 2015

Cognitive neuroscience, the study of brain-behavior relationships, has long attempted to map the brain. The discipline is flourishing, with an increasing number of functional neuroimaging studies appearing in the scientific literature daily. Unlike biology and even psychology, the cognitive neurosciences have only recently begun to apply evolutionary meta-theory and methodological guidance. Approaching cognitive neuroscience from an evolutionary perspective allows scientists to apply biologically based theoretical guidance to their investigations and can be conducted in both humans and nonhuman animals. In fact, several investigations of this sort are underway in laboratories around the world. This paper and two new volumes ( Platek, Keenan, and Shackelford [Eds.], 2007 ; Platek and Shackelford [Eds.], under contract) represent the first formal attempts to document the burgeoning field of evolutionary cognitive neuroscience. Here, we briefly review the current state of the science of evolutionary cognitive neuroscience, the methods available to the evolutionary cognitive neuroscientist, and what we foresee as the future directions of the discipline.
Information Behavior: A Socio-Cognitive Ability
Authors: Spink Amanda , Cole Charles
Published: July 2015

How has human information behavior evolved? Our paper explores this question in the form of notions, models and theories about the relationship between information behavior and human evolution. Alexander's Ecological Dominance and Social Competition/Cooperation (EDSC) model currently provides the most comprehensive overview of human traits in the development of a theory of human evolution and sociality. His model provides a basis for explaining the evolution of human socio-cognitive abilities, including ecological dominance, and social competition/cooperation. Our paper examines the human trait of information behavior as a socio-cognitive ability related to ecological dominance, and social competition/cooperation. The paper first outlines what is meant by information behavior from various interdisciplinary perspectives. We propose that information behavior is a socio-cognitive ability that is related to and enables other socio-cognitive abilities such as human ecological dominance, and social competition/cooperation. The paper reviews the current state of evolutionary approaches to information behavior and future directions for this research
Altruists Attract
Authors: Farrelly Daniel , Lazarus John , Roberts Gilbert
Published: July 2015

Explaining human cooperation continues to present a challenge because it goes beyond what is predicted by established theories of kinship and reciprocal altruism. Little attention has been paid to the sexual selection hypothesis that proposes that cooperation can act as a display that attracts mates. The costs of cooperating are then offset not by kinship or reciprocation but by increased mating success. Here we present results from a series of experiments which show that, as predicted by the sexual selection hypothesis, people preferentially direct cooperative behavior towards more attractive members of the opposite sex. Furthermore, cooperative behavior increases the perceived attractiveness of the cooperator. Economically costly behaviors can therefore bring benefits through mate choice and sexual selection should be regarded as an evolutionary mechanism capable of promoting cooperation.
The Major Histocompatibility Complex and Perfumers' Descriptions of Human Body Odors
Authors: Wedekind Claus , Escher Sina , Van de Waal Matthijs , Frei Elisabeth
Published: July 2015

The MHC (major histocompatibility complex) is a group of genes that play a crucial role in immune recognition and in tolerance of tissue grafting. The MHC has also been found to influence body odors, body odor preferences, and mate choice in mice and humans. Here we test whether verbal descriptions of human body odors can be linked to the MHC. We asked 45 male students to live as odor neutral as possible for two consecutive days and to wear a T-shirt during the nights. The odors of these T-shirts were then described by five evaluators: two professional perfumers and three laymen. One of the perfumers was able to describe the T-shirt odors in such a way that some of the allelic specificity of the MHC was significantly revealed (after Bonferroni correction for multiple testing). This shows that, although difficult, some people are able to describe MHC-correlated body odor components.
Competitive Status Signaling in Peer-to-Peer File-Sharing Networks
Authors: Lyle Henry F. , Sullivan Roger J.
Published: July 2015

Internet peer-to-peer file sharing is a contemporary example of asymmetrical sharing in which “altruists” (file uploaders) share unconditionally with non-reciprocating “free riders” (file downloaders). Those who upload digital media files over the Internet risk prosecution for copyright infringement, and are more vulnerable to computer hackers and viruses. In an analysis of file-sharing behavior among university undergraduates ( N=331), we found that significantly more males than females engaged in risky file uploading. Contrary to expectations, uploaders were not concerned about their reputation online and file sharers were not interested in identifying or chatting with uploaders while online. Among uploaders, males were more likely than females to be identified as uploaders by friends, to discuss uploading and to upload in the presence of peers. We interpret these results using costly-signaling theory, and argue that uploading is a costly signal in which males engage in avoidable risk taking as a means to compete for status among peers in social contexts other than the Internet.
Looking for Ms. Right: Allocating Attention to Facilitate Mate Choice Decisions
Authors: Suschinsky Kelly D. , Elias Lorin J. , Krupp Daniel Brian
Published: July 2015

Through various signals, the human body provides information that may be used by receivers to make decisions about mate value. Here, we investigate whether there exists a complementary psychological system designed to selectively attend to these signals in order to choose, and direct effort toward the acquisition of, a potential mate. We presented young men with three images of the same woman (six women in total) simultaneously, varying the waist-to-hip ratio (WHR) of each image while holding other traits constant. While participants chose their preferred image, we monitored visual attention using an infrared eye-tracker. We found that participants focused their attention selectively on body regions known to provide reproductive information in a manner consistent with the research hypothesis: Reproductively relevant body regions, especially the head and breasts, received the most visual attention. Likewise, images with lower WHRs and reproductively relevant regions in images with lower WHRs received the most visual attention and were chosen as most attractive. Finally, irrespective of WHR size, participants fixated more often and for longer durations on the images that they selected as most attractive.
Territory, Rank and Mental Health: The History of an Idea
Authors: Price John S. , Gardner Russell , Wilson Daniel R. , Sloman Leon , Rohde Peter , Erickson Mark
Published: July 2015

We trace the development of ideas about the relation of mood to social rank and territory. We suggest that elevated mood enabled a person to rise in rank and cope with the increased activities and responsibilities of a leadership role, while depressed mood enabled a person to accept low rank and to forego the rewards associated with high rank. This led to the concept of a trio of agonist/investor strategy sets, each consisting of escalating and de-escalating strategies, one set at each of the three levels of the triune forebrain. Depressed mood can be seen as a de-escalating (appeasement) strategy at the lowest (reptilian) level; this should facilitate de-escalation at the highest (rational) level, but sometimes this rational level de-escalation is blocked (e.g., by stubbornness, courage, pride or ambition) and then clinical depression may ensue. These evolved psychobiological mechanisms survived the partial transition from agonistic to prestige competition. We discuss difficulties which have arisen with our ideas, and their implications for clinical work and research.
Differences in Dietary Intake as a Function of Sexual Activity and Hormonal Contraception
Authors: Fleischman Diana S. , Fessler Daniel M. T.
Published: July 2015

As a consequence of the need to downregulate some maternal immune responses so as to tolerate paternal genetic material following conception, the luteal phase of the menstrual cycle is associated with increased susceptibility to infection. Because meat was one of the primary sources of foodborne pathogens throughout our evolutionary history, Fessler (2001) predicted a decrease in meat intake during the luteal phase; the current research provides the first test of this prediction. Based on the assumption that any such behavioral changes would be hormonally mediated, we also investigated the effects of varying levels of exogenous hormones on meat consumption by examining dietary intake in women using hormonal contraceptives. Lastly, because, from a functional perspective, immunomodulation is unnecessary during anovulatory cycles and in women who are not currently sexually active, luteal phase compensatory behavioral prophylaxis was predicted to be absent in these contexts. Although we find that women who are sexually active eat less meat than those who are not, we do not find support for the core prediction regarding effect of cycle phase on meat consumption, nor do we find support for the ancillary prediction that meat consumption would be influenced by the presence or withdrawal of exogenous hormones. We replicate the finding that periovulatory total food intake is decreased compared to the rest of the cycle and find that sexually active women show a greater periovulatory decrease in food intake than sexually inactive women.
Testing Predictions from the Hunter-Gatherer Hypothesis — 2: Sex Differences in the Visual Processing of near and Far Space
Authors: Sanders Geoff , Sinclair Kamila , Walsh Tom
Published: July 2015

Here, in the second of two linked reports, we focus on sex differences in visual processing. Study 1 presented a time estimation task in virtual space and generated the predicted Space*Sex interaction with men performing significantly better in far than in near space. Study 2 used a laboratory-based puzzle completion task in which participants saw their hands and the puzzle in far or near space. This time women performed significantly better in near than far space. Study 3 simplified the puzzle completion task. Once again the predicted Space*Sex interaction was significant but with both sexes showing significantly different performances: women better in near, men in far space. These findings are compatible with an evolutionary origin as predicted by the hunter-gatherer hypothesis. Far and near space are processed in the ventral and dorsal streams, two cortical regions more widely known as the “what” and “where” visual systems. To those traditional descriptions we suggest adding that the two streams are sex-dimorphic, with the ventral “there” system interacting with far space and favored in men and the dorsal “here” system interacting with near space and favored in women. Future studies of visual systems should consider the impact of sex differences and the spatial location of stimulus presentations.
Polymorphisms in the Dopamine D4 and D2 Receptor Genes and Reproductive and Sexual Behaviors
Authors: Eisenberg Dan T.A. , Campbell Benjamin , MacKillop James , Modi Meera , Dang David , Lum J. Koji , Wilson David S.
Published: July 2015

Human reproductive and sexual behaviors are heritable and may represent integral life history traits that are likely partially subserved by the dopamine system. Two dopamine receptor polymorphisms, DRD4 48bp VNTR and DRD2 TaqI A, were examined in relation to the Sexual-Orientation Inventory (SOI), age at first sexual intercourse, desired age of marriage, and desired age to have children in 195 (45% male) individuals from a general student population. As DRD4 7R alleles have been associated with migratory behavior, we also examined whether those with more 7R alleles had a greater frequency of multi-racial ancestries. Minor alleles of both polymorphisms (7R and A1 respectively) are believed to decrease the function of their respective receptors. Individuals with DRD4 7R alleles were more likely to have had sexual intercourse and to desire children earlier in life. In addition, DRD4 7R+ individuals were more likely to report multi-racial ancestries. Individuals with DRD2 A1 alleles were more likely to not want children and not want to marry. These results suggest that polymorphisms in the DRD4 and DRD2 genes are meaningfully associated with variation in reproductive and sexual behaviors. These results are provisionally interpreted as consistent with other findings suggesting that DRD4 7R and DRD2 A1 alleles are adaptive for lower offspring investment strategies in dynamic social environments.
Sex Differences in Performance with the Hand and Arm in near and Far Space: A Possible Effect of Tool Use
Authors: Sanders Geoff , Perez Marta
Published: July 2015

Using novel tasks, we tested two predictions from the hunter-gatherer hypothesis concerning sex differences in the motor control of hand and arm and in the visual processing of near and far space. In Study 1 we replicated earlier findings by demonstrating that women scored higher with the hand while men scored higher with the arm. Study 2 tested the motor and visual predictions concurrently and showed that the Muscle*Sex interaction, seen in Study 1, occurs in far as well as near space. However, we failed to confirm that women perform better with visual information from near and men from far space. Instead the relative performance of women and men was the same in far as it was in near space. Drawing on evidence from studies of selective visual neglect we suggest that this outcome arose because tool use causes far space to be re-mapped as near space. Finally, the selective visual neglect literature indicates that the processing of far and near space is located in the ventral and dorsal cortical streams, previously described as two “what”/“where” visual systems. We draw attention to their additional “there”/“here” functions that are sex dimorphic and, as we have shown, modulated by tool use.
Decision Strategies in Continuous Ratings of Jealousy Feelings Elicited by Sexual and Emotional Infidelity
Authors: Schützwohl Achim
Published: July 2015

Two studies (total N = 689) tested the assumption of DeSteno, Bartlett, Braverman, and Salovey (2002) that sex differences in jealousy predicted by the evolutionary view are an artifact of measurement because they are restricted to a forced-choice response format and do not emerge when using continuous jealousy ratings. In Study 1, men and women rated how much a mate's emotional and sexual infidelity contributed to their jealousy feeling. In Study 2, men and women rated the intensity of their jealousy feeling elicited by a mate's emotional and sexual infidelity. In one condition they were asked to make their ratings spontaneously whereas in the other condition they were instructed to make their ratings only after careful consideration. The results of both studies lend no support for the artifact-of-measurement assumption. The implications of the present finding for the assumption of DeSteno et al. (2002) are discussed.
Parental Investment in Children with Chronic Disease: The Effect of Child's and Mother's Age
Authors: Tifferet Sigal , Manor Orly , Constantini Shlomi , Friedman Orna , Elizur Yoel
Published: July 2015

Parents do not invest their resources in their children equally. Three factors which elicit differential parental investment are the parent's reproductive value, the child's reproductive value (RV), and the impact of the investment on the child (II). As the child matures, his RV increases while the II may decrease. This raises a question regarding the favored strategy of investment by child age. It was hypothesized that different categories of parental investment generate different age-based strategies. Emotional investment, such as maternal worrying for the child's health, was hypothesized to increase with the child's age, while direct care was hypothesized to decrease with the child's age. Both categories were hypothesized to increase with the mother's age at childbirth. 137 Israeli mothers of children with chronic neurological conditions reported levels of worrying for their child and levels of change in direct care. Maternal worrying about the child's health was positively associated with the child's age at diagnosis and the severity of his illness, and negatively associated with the time from diagnosis. An increase in direct care was positively associated with maternal age at childbirth and illness severity, and negatively associated with the time from diagnosis, and the duration of the marriage. Contrary to the hypothesis, the child's age had no effect on changes in direct care. It appears that in mothers of children with adverse neurological conditions, child and maternal age effect parental investment differently. While the child's age is related to maternal worrying about his health, the mother's age at childbirth is related to changes in direct care.
Persistent Misunderstandings of Inclusive Fitness and Kin Selection: Their Ubiquitous Appearance in Social Psychology Textbooks
Authors: Park Justin H.
Published: July 2015

Inclusive fitness theory and kin selection theory are among the most recognizable theories associated with evolutionary biology and psychology—they are also among the most widely misunderstood. The problem begins early, in undergraduate psychology textbooks. Here, ten social psychology textbooks were reviewed, and they were all found to contain at least one form of misunderstanding. Because these misunderstandings appear to result partly from people's intuitions about kinship and adaptive behavior (which are not necessarily in line with the scientific theories), writers must be especially vigilant in order to combat the misunderstandings.
Sex Differences in the Value of Parents versus Same-Sex Peers
Authors: Benenson Joyce F. , Saelen Cécile , Markovits Henry , McCabe Sarah
Published: July 2015

The current research examined the hypothesis that males derive greater benefits than females do from cooperation with same-sex peers versus parents. In Study 1, 194 children, early adolescents, older adolescents, and adults from Brussels, Belgium predicted whether parents or same-sex peers would provide more benefits to a typical individual of their same age and sex. Results showed that at all four age levels, compared with females, males predicted that same-sex peers would provide more benefits relative to parents. Study 2 was designed to examine which benefits same-sex peers relative to parents provide more for males than females. In Study 2, 50 young adults from Montreal, Canada were asked to report to what extent same-sex peers and parents satisfied physical needs, fulfilled socioemotional needs, and helped with acquiring societal skills over the past year. Males more than females reported that same-sex peers relative to parents satisfied socioemotional needs and helped with the acquisition of societal skills. Discussion revolves around the hypothesized differential relations of males and females to families versus same-sex peers.
Sex Differences in Everyday Risk-Taking Behavior in Humans
Authors: Pawlowski B. , Atwal Rajinder , Dunbar R.I.M.
Published: July 2015

Sexual selection theory predicts that males will tend to behave in ways that are more risky than females. We explored this in humans by studying two everyday situations (catching a bus and crossing a busy road). We show that humans are competent optimizers on such tasks, adjusting their arrival times at a bus stop so as to minimize waiting time. Nonetheless, single males pursue a more risky strategy than single females by cutting waiting times much finer. Males are also more likely than females to cross busy roads when it is risky to do so. More importantly, males are more likely to initiate a crossing in high risk conditions when there are females present in the immediate vicinity, but females do not show a comparable effect in relation to the number of males present. These results support the suggestion that risk-taking is a form of “showing off” used as mate advertisement.
The Bilingual Brain: Human Evolution and Second Language Acquisition
Authors: Hagen L. Kirk
Published: July 2015

For the past half-century, psycholinguistic research has concerned itself with two mysteries of human cognition: (1) that children universally acquire a highly abstract, computationally complex set of linguistic rules rapidly and effortlessly, and (2) that second language acquisition (SLA) among adults is, conversely, slow, laborious, highly variable, and virtually never results in native fluency. We now have a decent, if approximate, understanding of the biological foundations of first language acquisition, thanks in large part to Lenneberg's (1964, 1984) seminal work on the critical period hypothesis. More recently, the elements of a promising theory of language and evolution have emerged as well (see e.g. Bickerton, 1981 , 1990 ; Leiberman, 1984, 1987). I argue here that the empirical foundations of an evolutionary theory of language are now solid enough to support an account of bilingualism and adult SLA as well. Specifically, I will show that evidence from the environment of evolutionary adaptation of paleolithic humans suggests that for our nomadic ancestors, the ability to master a language early in life was an eminently useful adaptation. However, the ability to acquire another language in adulthood was not, and consequently was not selected for propagation.
Anorexic Behavior, Female Competition and Stress: Developing the Female Competition Stress Test
Authors: Salmon Catherine , Crawford Charles B. , Walters Sally
Published: July 2015

The FCST (Female-Female Competition Stress Test) was constructed to assess stress from adolescent female-female competition. Such stress is particularly relevant to the Reproductive Suppression Hypothesis that has been suggested as one possible explanation for the development of anorexic type behavior in young women. A series of items generated an initial test in the first phase of development. In the second phase, three studies were conducted to assess reliability and validity. Female undergraduates retrospectively rated the female-female competition stress they had experienced as adolescents, and their responses were factor-analyzed. In a second group of subjects, FCST scores were correlated with a measure of anxiety. In the third study, three samples provided prototypicality ratings of the test items to determine both the agreement among raters and which items were not sufficiently prototypical of female-female competition stress to be retained. In the final phase, the responses of adolescent girls to the FCST and several measures of body image were factor analyzed, showing the utility of the FCST.