MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Evolution and Human Behaviour' source. Thu, 09 Feb 2012 02:31:45 +0100 http://www.medworm.com/index.php?rid=5497239&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811001206%2Fabstract%3Frss%3Dyes (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497239 Tue, 13 Dec 2011 20:29:02 +0100 5497239 http://www.medworm.com/index.php?rid=5288710&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000663%2Fabstract%3Frss%3Dyes Robert Kurzban is a consortium of modules based at the University of Pennsylvania. They (those modules, or some subset of them) have recently written a very interesting book about self-deception and hypocrisy. You (whoever you are) are reading a review of that book. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288710 Fri, 02 Sep 2011 04:00:00 +0100 5288710 http://www.medworm.com/index.php?rid=5497237&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381100050X%2Fabstract%3Frss%3Dyes Abstract: Cooperative hunting is often assumed to be mutualistic, maintained through returns to scale, where, by working together, foragers can gain higher per capita return rates or harvest sizes than they can by hunting alone. We test this hypothesis among Martu hunters and find that cooperation only provides increased returns to poorer hunters while disadvantaging better hunters. Even so, better hunters still cooperate as frequently as poorer hunters. We ask whether better hunters are advantaged in secondary sharing distributions or whether they bias their partner choice to kin or household members. We find that better hunters are not more likely to pair up with kin and they do not gain consumption benefits from acquiring more. They share a greater proportion of their harvest than poore... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497237 Tue, 16 Aug 2011 04:00:00 +0100 5497237 http://www.medworm.com/index.php?rid=5497236&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000493%2Fabstract%3Frss%3Dyes Abstract: Evolutionary theories (e.g., the challenge hypothesis) suggest that testosterone plays an important role in intrasexual competition. In addition, those theories suggest that testosterone responses during competition should depend upon the presence of potential, immediate mating opportunities associated with the competition. The current research tested the hypothesis that the sex composition of individuals at a competition (ratio of opposite-sex, potential mates to same-sex individuals) would influence changes in competitors' testosterone levels. Consistent with our hypotheses, higher ratios of opposite- to same-sex individuals at an ultimate frisbee tournament were associated with greater increases in salivary testosterone among competitors. The relationship between sex ratio and... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497236 Tue, 16 Aug 2011 04:00:00 +0100 5497236 http://www.medworm.com/index.php?rid=5497235&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000481%2Fabstract%3Frss%3Dyes Abstract: Reasoning about the evolution of our species' capacity for cumulative cultural learning has led culture–gene coevolutionary (CGC) theorists to predict that humans should possess several learning biases which robustly enhance the fitness of cultural learners. Meanwhile, developmental psychologists have begun using experimental procedures to probe the learning biases that young children actually possess — a methodology ripe for testing CGC. Here we report the first direct tests in children of CGC's prediction of prestige bias, a tendency to learn from individuals to whom others have preferentially attended, learned or deferred. Our first study showed that the odds of 3- and 4-year-old children learning from an adult model to whom bystanders had previously preferentially attende... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497235 Tue, 16 Aug 2011 04:00:00 +0100 5497235 http://www.medworm.com/index.php?rid=5497233&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000468%2Fabstract%3Frss%3Dyes Abstract: The persistence of left-handers in every human population studied to date is an evolutionary puzzle in light of evidence of survival costs associated with left-handedness. Associations between left-handedness and socioeconomic advantages have been observed in Western countries and could provide left-handers fitness benefits through higher survival chances and greater reproductive success. We aimed to explore the generality of this result in another culture. For this purpose, we investigated several socioeconomic status indicators and the number of children alive for 917 men and women in Uzbekistan and compared results for two different measures of handedness: hand preferences for writing and for knife use. Among both men and women, left-handed writers were significantly more like... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497233 Tue, 16 Aug 2011 04:00:00 +0100 5497233 http://www.medworm.com/index.php?rid=5112860&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000687%2Fabstract%3Frss%3Dyes In of the above-mentioned article, the table footnote was presented incorrectly. is reprinted below with the correct footnote information. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112860 Thu, 11 Aug 2011 08:39:44 +0100 5112860 http://www.medworm.com/index.php?rid=5497238&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000444%2Fabstract%3Frss%3Dyes Before Principles of Social Evolution, when social scientists or economists asked me to recommend a book on the evolution of cooperation, I never quite knew what to say. , the stalwart of undergraduate Zoology courses, is an excellent, example-laden introduction to social evolution and the wider field, but is too basic for most. he Major Transitions in Evolution (1995) illustrates the importance of sociality but lacks the conceptual framework that explains how it evolves. At the other extreme, oundations of Social Evolution (1998) explains the theory but does not discuss any empirical work. I usually suggest this trilogy and some more recent review papers (e.g. ). Now I will just direct people to the Principles of Social Evolution. This highly readable account uses the conceptual framework... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497238 Fri, 05 Aug 2011 04:00:00 +0100 5497238 http://www.medworm.com/index.php?rid=5497232&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000456%2Fabstract%3Frss%3Dyes We examined how coresidence duration — a cue that would have indicated genetic relatedness in ancestral environments — impacts the development of kin-directed behaviors. In both studies, we found that coresidence duration predicts levels of altruism and sexual aversions directed toward peers. We also investigated the relationship between personal sexual aversions and moral attitudes relating to peer sexual behavior. The absence of norms proscribing sex between peers on the Kibbutz allows for a more tightly controlled investigation of this relationship. We found that total coresidence duration with opposite-sex peers predicts the intensity of moral wrongness associated with third-party peer sexual behavior, but not other behaviors, including sibling incest. More directly, we found that ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497232 Fri, 05 Aug 2011 04:00:00 +0100 5497232 http://www.medworm.com/index.php?rid=5497234&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381100047X%2Fabstract%3Frss%3Dyes Abstract: Human speech evidently conveys an adaptive advantage, given its apparently rapid dissemination through the ancient world and global use today. As such, speech must be capable of altering human biology in a positive way, possibly through those neuroendocrine mechanisms responsible for strengthening the social bonds between individuals. Indeed, speech between trusted individuals is capable of reducing levels of salivary cortisol, often considered a biomarker of stress, and increasing levels of urinary oxytocin, a hormone involved in the formation and maintenance of positive relationships. It is not clear, however, whether it is the uniquely human grammar, syntax, content and/or choice of words that causes these physiological changes, or whether the prosodic elements of speech, whic... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497234 Mon, 01 Aug 2011 04:00:00 +0100 5497234 http://www.medworm.com/index.php?rid=5497230&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000419%2Fabstract%3Frss%3Dyes Abstract: We use data from the National Incident-Based Reporting System to examine the effects of offender and victim age on whether male offenders commit sexual assault while robbing women. Restricting analyses to robberies reveals the offenders' age preferences since it allows one to control for the effects of opportunity. We find that robbers of all ages are most likely to sexually assault women at ages 15–29 years, ages when their reproductive potential is highest. However, in contrast to the idea that rape is a direct adaptation, victims are no more likely to be raped than sexually assaulted at these ages. The age of the offender is also a strong predictor of sexual assault. The likelihood that a robber commits a sexual assault increases from age 12 years until he reaches his early ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497230 Fri, 22 Jul 2011 04:00:00 +0100 5497230 http://www.medworm.com/index.php?rid=5112859&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000407%2Fabstract%3Frss%3Dyes “If you are faced by a difficulty or a controversy in science, an ounce of algebra is worth a ton of verbal argument.”—attributed to J. B. S. Haldane (Maynard ) The problem of cooperation is central to the evolutionary and social sciences. Altruism so bothered Darwin that he thought it ‘fatal to the whole theory' of evolution by natural selection. In the 1960s and 1970s, sociobiology overcame Darwin's ‘special difficulty,' laying down a solid theoretical foundation on which to build a theory of social evolution. This foundation includes Hamilton's reformulation of natural selection as a force that maximizes “inclusive fitness” rather than individual fitness, George Williams' expository evisceration of old-school group selection, Robert Trivers' explanation of cooperation bet... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112859 Thu, 21 Jul 2011 23:00:00 +0100 5112859 http://www.medworm.com/index.php?rid=5497231&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000432%2Fabstract%3Frss%3Dyes Abstract: Friendship is a core aspect of human social life. Friends form long-term, cooperative relationships, and provide material and emotional support for one another. Previous research in social psychology suggests that people prefer balanced relationships over unbalanced relationship with friends, but at the same time, friendship is defined by an absence of direct reciprocity and careful tracking of favors given and received. The goal of this study was to distinguish between differences in tracking and tolerance of imbalances among friends and strangers. We conducted parallel behavioral economic experiments in three different urban cultural settings, USA, Japan and China, in an effort to expand our understanding of the dynamics of human friendship. Across all sites, we found that subj... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497231 Thu, 21 Jul 2011 04:00:00 +0100 5497231 http://www.medworm.com/index.php?rid=5112858&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000420%2Fabstract%3Frss%3Dyes This article looks at two articles recently published here, one by R. Hopcroft [“Sex, status, and reproductive success in the contemporary United States,” Evolution and Human Behavior 27 (2006) 104–120] the second by M. Fieder and S. Huber [“The effects of sex and childlessness on reproductive effort in modern humans,” Evolution and Human Behavior 28 (2007) 392–398]. They both report a positive relationship between male income and male fertility, which marks a real advancement in our knowledge. Hopcroft speculates at the end of her article that the father's status and female fertility will be positive, too. At this point, this will depend on her and others' reaction to the efforts of S. Huber, F. Bookstein, and M. Fiedler. (2010). Socioeconomic status, education, and reproducti... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112858 Wed, 20 Jul 2011 23:00:00 +0100 5112858 http://www.medworm.com/index.php?rid=5288708&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000274%2Fabstract%3Frss%3Dyes Abstract: Intralocus sexual conflict (IASC) occurs when sex-specific selection favors genes that increase fitness in one sex and decrease fitness in the other sex. The current study was designed to explore whether IASC occurs in humans. In a sample of siblings, we identified and measured sexually dimorphic traits and hormones within each sex that are related to fitness and are likely coded for by antagonistic genes: waist-to-hip ratio (WHR) and breast size in women, WHR and bicep size (an index of muscularity) in men, and estradiol (E) and testosterone (T) in both sexes. If these traits and hormones are coded for by genes under IASC, masculine or feminine expression of traits and hormones should differentially predict brothers' and sisters' fitness. Consistent with an IASC model, both men ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288708 Wed, 15 Jun 2011 04:00:00 +0100 5288708 http://www.medworm.com/index.php?rid=5497229&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000250%2Fabstract%3Frss%3Dyes Abstract: It has been hypothesized that female orgasm evolved to facilitate recruitment of high-quality genes for offspring. Supporting evidence indicates that female orgasm promotes conception, although this may be mediated by the timing of female orgasm in relation to male ejaculation. This hypothesis also predicts that women will achieve orgasm more frequently when copulating with high-quality males, but limited data exist to support this prediction. We therefore explored relationships between the timing and frequency of women's orgasms and putative markers of the genetic quality of their mates, including measures of attractiveness, facial symmetry, dominance, and masculinity. We found that women reported more frequent and earlier-timed orgasms when mated to masculine and dominant men�... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5497229 Fri, 10 Jun 2011 04:00:00 +0100 5497229 http://www.medworm.com/index.php?rid=5288707&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000237%2Fabstract%3Frss%3Dyes This study tested if women would outperform men in laboratory-based computer tests of search and gathering skills. In Experiment 1, men found target objects faster and made fewer mistakes than women in a classic visual search study. In Experiment 2, participants gathered items (fruits or letters presented on screen), and again, men performed significantly better. In Experiment 3, participants' incidental learning of object locations in a search experiment was studied, but no statistically significant sex differences were observed. These findings found the opposite of what was expected based on the hypothesis that female cognition has adapted to gathering. Alternative interpretations of the role of object location memory, female gathering roles and the division of labor between the sexes ar... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288707 Thu, 09 Jun 2011 04:00:00 +0100 5288707 http://www.medworm.com/index.php?rid=5288704&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000249%2Fabstract%3Frss%3Dyes Abstract: Developmental instability (DI) reflects the inability of a developing organism to buffer its development against random perturbations, due either to frequent, large perturbations or to a poor buffering system. The primary measure used to assess DI experienced by an individual organism is fluctuating asymmetry (FA), asymmetry of bilateral features that are, on average in a population, symmetrical. A large literature on FA in humans in relation to measures of health and quality (close to 100 studies and nearly 300 individual effect size estimates) has accumulated. This paper presents the first quantitative meta-analysis of this literature. The mean effect size (scaled as Pearson r) was about 0.2. Effect sizes covaried negatively with sample size, consistent with effects of publicat... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288704 Thu, 09 Jun 2011 04:00:00 +0100 5288704 http://www.medworm.com/index.php?rid=5288706&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000225%2Fabstract%3Frss%3Dyes Abstract: Differential grandparental investment in grandchildren is often explained with paternity uncertainty. The asymmetric inheritance of the sex chromosomes, especially of the X chromosomes, may also bias grandparental investment. Recent studies show that ignoring the sex of the grandchild can mask important differences in the investment patterns of the same grandparent category, but this has not been tested in contemporary societies with nationally representative data. With 17 variables from the Involved Grandparenting and Child Well-Being 2007 survey, we tested differential grandparental investment as reported by British and Welsh adolescents and compared predictions based on X-chromosomal relatedness with predictions based on paternity uncertainty. The theories are expected to diff... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288706 Wed, 08 Jun 2011 04:00:00 +0100 5288706 http://www.medworm.com/index.php?rid=4907302&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000262%2Fabstract%3Frss%3Dyes One would hope that a reader entitled Evolution, Literature, and Film would clear several basic hurdles. For starters, one would look for the book to eschew disciplinary boundaries, to swing nimbly from primatology to neuroscience, from standard psychology to Shakespeare to Pudovkin's conception of montage. This book certainly commands that range—on one page one reads about Darwin's theory of emotions as it inheres in the stoic celluloid visage of Clint Eastwood, on another about the resourcefulness of Homeric women, and a chapter traces a lineage leading directly from Shakespeare to When Harry Met Sally and Taxi Driver. Similarly, one would hope for a reasonably ecumenical range of ways that evolutionary theory might be applied to these art forms, and in this regard the book delivers in... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4907302 Wed, 04 May 2011 23:00:00 +0100 4907302 http://www.medworm.com/index.php?rid=4907299&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000043%2Fabstract%3Frss%3Dyes Abstract: The evolution of cooperation through partner choice mechanisms is often thought to involve relatively complex cognitive abilities. Using agent-based simulations, I model a simple partner choice rule, the “Walk Away” rule, where individuals stay in groups that provide higher returns (by virtue of having more cooperators), and “Walk Away” from groups providing low returns. Implementing this conditional movement rule in a public goods game leads to a number of interesting findings: (a) cooperators have a selective advantage when thresholds are high, corresponding to low tolerance for defectors, (b) high thresholds lead to high initial rates of movement and low final rates of movement (after selection), and (c) as cooperation is selected, the population undergoes a spatial tr... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4907299 Sun, 01 May 2011 23:00:00 +0100 4907299 http://www.medworm.com/index.php?rid=4728610&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000146%2Fabstract%3Frss%3Dyes When I was studying for my Ph.D. in the psychology of children's interactions with pets in the early 1990s, “anthrozoologists” were a rare and obscure breed. Journalists and TV producers were always keen to interview us about our work, but the wider academic community was largely uninterested. Studies of people's varied and diverse relationships with animals were regarded as quirky and “special interest”, not really the stuff of serous scientific or ethnographic research. Twenty years later, things have begun to change. Although anthrozoology is still not a large field, the fascinating and sometimes baffling interface between humans and our fellow creatures is a much more acceptable topic for discussion and intellectual discourse. Even the National Institutes of Health has recently... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728610 Wed, 20 Apr 2011 07:22:21 +0100 4728610 http://www.medworm.com/index.php?rid=4728608&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000055%2Fabstract%3Frss%3Dyes Abstract: Moral judgment involves much more than computations of the expected consequences of behavior. A prime example of the complexity of moral thinking is the frequently replicated finding that violations by omission are judged less morally wrong than violations by commission, holding intentions constant. Here we test a novel hypothesis: Omissions are judged less harshly because they produce little material evidence of wrongdoing. Evidence is crucial because moral accusations are potentially very costly unless supported by others. In our experiments, the omission effect was eliminated when physical evidence showed that an omission was chosen. Perpetrators who “opted out” by pressing a button that would clearly have no causal effects on the victim, rather than rescuing them, were ju... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728608 Wed, 30 Mar 2011 23:00:00 +0100 4728608 http://www.medworm.com/index.php?rid=5288705&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513811000031%2Fabstract%3Frss%3Dyes Abstract: Cumulative cultural evolution requires that information is faithfully transmitted from generation to generation. The present study examines the role of agent interaction as a social learning mechanism through which information is transmitted across multiple generations. The performance of two types of linear transmission chains was compared: noninteractive (agents in adjacent chain positions were not permitted to interact) and interactive (adjacent agents freely interacted with one another). In both conditions, information (details of a narrative text) was lost as it was passed along the transmission chain. However, interactive transmission chains promoted more accurate recall of information than noninteractive chains. A content analysis revealed that most listeners actively part... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288705 Fri, 25 Mar 2011 04:00:00 +0100 5288705 http://www.medworm.com/index.php?rid=5112857&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381100002X%2Fabstract%3Frss%3Dyes Abstract: In preindustrial societies, kin may exert influence on the mating choices of women, but there have been few systematic studies of the preferred characteristics of husbands for female kin. In an indigenous Mayangna and Miskito community, photographs of 29 male household heads were presented to informants, who ranked the men on three characteristics: desirability as a spouse, hunting ability and wealth. For the desirability rankings, informants were asked to consider the advice that they would give to young female relatives and rank the men based on the qualities that such women should seek in a husband. Consensus analysis indicates that there is high agreement among informants on all three sets of rankings. There is no evidence that the age and sex of informants are associated wit... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112857 Wed, 23 Mar 2011 00:00:00 +0100 5112857 http://www.medworm.com/index.php?rid=5288703&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001431%2Fabstract%3Frss%3Dyes Abstract: Little is known of the foraging abilities of children in modern cultures, especially when children forage in groups. Here we present a test of optimal foraging theory in groups of street children working for money. The children we observed were selling bottles of water to drivers distributed in two lanes at a crossroad of Istanbul, Turkey. As predicted by the ideal free distribution (a model of optimal group foraging), the ratio of children working in the two lanes was sensitive to the ratio of cars (and therefore the ratio of potential buyers) present in each lane. Deviations from the ideal free model arose largely from numerical restrictions on the set of possible ratios compatible with a small group size. When these constraints were taken into account, optimal behavior emerged... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288703 Fri, 18 Mar 2011 04:00:00 +0100 5288703 http://www.medworm.com/index.php?rid=5112856&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001455%2Fabstract%3Frss%3Dyes Abstract: Drawing from costly signaling theory, we predicted that luxury consumption enhances status and produces benefits in social interactions. Across seven experiments, displays of luxury — manipulated through brand labels on clothes — elicited different kinds of preferential treatment, which even resulted in financial benefits to people who engaged in conspicuous consumption. Furthermore, we tested preconditions in which the beneficial consequences of conspicuous consumption may arise and determined the proximate mechanisms underlying them. The present data suggest that luxury consumption can be a profitable social strategy because conspicuous displays of luxury qualify as a costly signaling trait that elicits status-dependent favorable treatment in human social interactions. (Sou... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112856 Fri, 18 Mar 2011 00:00:00 +0100 5112856 http://www.medworm.com/index.php?rid=5112855&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001443%2Fabstract%3Frss%3Dyes Abstract: Analytical models have identified a set of social learning strategies that are predicted to be adaptive relative to individual (asocial) learning. In the present study, human participants engaged in an ecologically valid artifact-design task with the opportunity to engage in a range of social learning strategies: payoff bias, conformity, averaging and random copying. The artifact (an arrowhead) was composed of multiple continuous and discrete attributes which jointly generated a complex multimodal adaptive landscape that likely reflects actual cultural fitness environments. Participants exhibited a mix of individual learning and payoff-biased social learning, with negligible frequencies of the other social learning strategies. This preference for payoff-biased social learning was... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112855 Thu, 17 Mar 2011 00:00:00 +0100 5112855 http://www.medworm.com/index.php?rid=5288709&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001418%2Fabstract%3Frss%3Dyes Abstract: Life history theory predicts a trade-off between fitness benefits and costs of delaying age at first reproduction (AFR). In many human populations, maternal AFR has been increasingly delayed beyond sexual maturity over the past decades, raising a question of whether any fitness benefits accrued outweigh costs incurred. To investigate the cost–benefit trade-off concerning AFR in women, we construct a theoretical model and test its predictions using pedigree data from historical Finnish mothers. The model predicts that the probability of reproductive failure (no offspring produced reaching breeding) will increase with AFR if the benefit with delaying in terms of improvement to offspring quality (i.e., breeding probability) cannot offset the cost from decline in offspring quantity... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5288709 Thu, 24 Feb 2011 05:00:00 +0100 5288709 http://www.medworm.com/index.php?rid=5112853&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001261%2Fabstract%3Frss%3Dyes This study supports the hypothesis that PGM behavior differs according to her grandchild's sex. Further research should now explore the biological mechanism underlying this phenomenon. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112853 Fri, 18 Feb 2011 00:00:00 +0100 5112853 http://www.medworm.com/index.php?rid=5112852&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381000142X%2Fabstract%3Frss%3Dyes Abstract: Wealth and status covary with lifetime reproductive success in preindustrial human populations. Local ecology is likely to modify this association, but details of this presumed relationship are not yet known. We sought to determine whether local ecology modifies the relationship between status and fitness (number of grandchildren). Our approach to the problem was to measure variation in fitness relative to status (landless or with land) and to local ecology (inland versus coastal communities). We also analyzed life history traits that might explain observed variations in fitness. Our results confirm previous findings that both status (landless=9.9 vs. with land=16.5) and ecology (inland=12.3 vs. coast=14.1) affect the number of grandchildren produced by a female in pre-industrial... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112852 Thu, 17 Feb 2011 00:00:00 +0100 5112852 http://www.medworm.com/index.php?rid=4728603&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001248%2Fabstract%3Frss%3Dyes Abstract: The presence of subtle cues of being watched has been reported to make people behave altruistically, even when they are anonymous. Individual selection theory predicts that generosity in the presence of eyes is based on the providers' expectation of a future reward. On the other hand, as we are living in quite a large society in which altruistic punishment is effective, the eyes could elicit fear of punishment. However, no previous study has investigated whether people are concerned with their reputation when subtle social cues are present. We conducted the dictator game in the presence of, or without, a painting of stylized eyes. The participants were then asked to complete a post-experimental questionnaire designed to investigate what they were thinking when they decided the am... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728603 Mon, 14 Feb 2011 00:00:00 +0100 4728603 http://www.medworm.com/index.php?rid=4467493&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001236%2Fabstract%3Frss%3Dyes Abstract: Visual assessments of relatedness may affect paternal investment decisions and altruistic behaviors. Work examining preferences for cues to self-resemblance in child faces has been equivocal, with findings showing that men have a higher preference than women, that preference for self-resemblance was statistically significant in women but not men, and that both men and women have a significant preference for self-resemblance when making parental investment decisions. Using data from 67 heterosexual romantic couples, we present evidence that both men and women prefer self-resembling infants, but show no significant preference for partner-resembling infants. Moreover, men's intersexual negative inducement tactics were correlated with, and significantly predicted, their preferences f... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467493 Sat, 12 Feb 2011 20:44:20 +0100 4467493 http://www.medworm.com/index.php?rid=5112854&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381000125X%2Fabstract%3Frss%3Dyes Abstract: When predicting the next outcome in a sequence of events, people often appear to expect streaky patterns, such as that sport players can develop a “hot hand,” even if the sequence is actually random. This expectation, referred to as positive recency, can be adaptive in environments characterized by resources that are clustered across space or time (e.g., expecting to find multiple berries on separate bushes). But how strong is this disposition towards positive recency? If people perceive random sequences as streaky, will there be situations in which they forego a payoff because they prefer an unpredictable random environment over an exploitable but alternating pattern? To find out, 238 participants repeatedly chose to bet on the next outcome of one of two sequences of (binary... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112854 Thu, 10 Feb 2011 00:00:00 +0100 5112854 http://www.medworm.com/index.php?rid=4728605&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001212%2Fabstract%3Frss%3Dyes Abstract: Many aspects of personality are honestly signaled on the human face, as shown by accurate identification of personality traits from static images of unknown faces with neutral expressions. Here, we examined the evolutionary history of this signal system. In four studies, we found that untrained human observers reliably discriminated characteristics related to extraversion solely from nonexpressive facial images of chimpanzees (Pan troglodytes). In chimpanzees, as in humans, there is therefore information in the static, nonexpressive face that signals aspects of an individual's personality. We suggest that this performance is best explained by shared personality structure and signaling in the two species. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728605 Tue, 18 Jan 2011 00:00:00 +0100 4728605 http://www.medworm.com/index.php?rid=4467496&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001200%2Fabstract%3Frss%3Dyes This study illustrates both the potency of sexual selection in polygynous human populations and the dramatic influence that short-term societal changes can have on evolutionary processes. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467496 Tue, 18 Jan 2011 00:00:00 +0100 4467496 http://www.medworm.com/index.php?rid=4467491&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001182%2Fabstract%3Frss%3Dyes Abstract: Evolutionary models of parental investment often assume that negative effects of competition between offspring (i.e., quantity-quality trade-off effects) will be most apparent under conditions of resource scarcity. However, improvements in resource access associated with “modernization” may reduce levels of extrinsic environmental risk, creating a stronger association between parental investment and offspring success. Here we provide evidence that a rural development initiative in Ethiopia is associated with increased levels of parental investment in offspring status and increased levels of competition for this investment between siblings. Villages with access to an improved water supply, which have reduced levels of childhood mortality, are associated with higher investments... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467491 Tue, 18 Jan 2011 00:00:00 +0100 4467491 http://www.medworm.com/index.php?rid=4907301&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001273%2Fabstract%3Frss%3Dyes Abstract: Long-distance throwing is uniquely human and enabled Homo sapiens to survive and even thrive during the ice ages. The precise motoric timing required relates throwing and speech abilities as dependent on the same uniquely human brain structures. Evidence from studies of brain evolution is consistent with this understanding of the evolution and success of H. sapiens. Recent theories of language development find readiness to develop language capabilities in perceptual biases that help generate ability to detect relevant higher order acoustic units that underlie speech. Might human throwing capabilities exhibit similar forms of readiness? Recently, human perception of optimal objects for long-distance throwing was found to exhibit a size–weight relation similar to the size–weigh... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4907301 Wed, 12 Jan 2011 00:00:00 +0100 4907301 http://www.medworm.com/index.php?rid=5112851&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001194%2Fabstract%3Frss%3Dyes Abstract: Many animal species have morphological and cognitive adaptations for fighting with others to gain resources, but it remains unclear how humans make fighting decisions. Non-human animals adaptively calibrate fighting behavior to ecological variables such as resource quantity and resource distribution. Also, many species reduce fighting costs by resolving disputes based on power asymmetries or conventions. Here we show that humans apply an ownership convention in response to the problem of costly fighting. We designed a virtual environment where participants, acting as avatars, could forage and fight for electronic food items (convertible to cash). In two experimental conditions, resources were distributed uniformly or clustered in patches. In the patchy condition, we observed an o... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=5112851 Wed, 05 Jan 2011 00:00:00 +0100 5112851 http://www.medworm.com/index.php?rid=4728607&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001170%2Fabstract%3Frss%3Dyes Abstract: Reciprocity evolves only when social partners reliably repay, with interest, the investments of others. However, not all individuals are equally able—or motivated—to recompense others satisfactorily. As such, reciprocity relies greatly on the capacities and motives of partners. Apparent health may provide a cue to the value of potential exchange partners in this regard: healthier individuals will tend to live longer and accrue more, higher quality resources, thus increasing the incentives for mutual cooperation. In a monetary exchange task, we show that the apparent health of partners' faces affects human reciprocity. Specifically, participants were more willing to return a profitable amount to, but not more willing to invest in, apparently healthy than unhealthy partners. Th... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728607 Wed, 05 Jan 2011 00:00:00 +0100 4728607 http://www.medworm.com/index.php?rid=4728609&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001169%2Fabstract%3Frss%3Dyes We present three studies investigating the contribution of carotenoid and melanin to skin color and the healthy appearance of human faces. Study 1 demonstrates similar perceptual preferences for increased skin L* and b* in UK-based Caucasian and black South African populations. Study 2 shows that individuals with higher dietary intakes of carotenoids and fruit and vegetables have increased skin b* values and show skin reflectance spectra consistent with enhanced carotenoid absorption. Study 3 shows that, to maximize apparent facial health, participants choose to increase empirically derived skin carotenoid coloration more than melanin coloration in the skin portions of color-calibrated face photographs. Together our studies link skin carotenoid coloration to both perceived health and healt... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728609 Fri, 24 Dec 2010 00:00:00 +0100 4728609 http://www.medworm.com/index.php?rid=4467489&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000930%2Fabstract%3Frss%3Dyes Abstract: Human fathers are heavily involved in the rearing of children around the world. Early evolutionary explanations focused on the greater need of human children and mothers compared to other species and the consequent increased benefits available to investing fathers and pair-bonded husbands. Contrary to this hypothesis, research suggests that the impact of men's care on the survivorship and physical well-being of juvenile offspring is cross-culturally variable and often unsubstantial. Proper testing of the hypothesis, however, also requires exploring how well children raised with paternal investment fare as adults, compared to those raised in the absence of fathers. We explore this issue among the Tsimane, who exhibit high levels of paternal provisioning and very low divorce rates,... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467489 Wed, 22 Dec 2010 00:00:00 +0100 4467489 http://www.medworm.com/index.php?rid=4256057&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001005%2Fabstract%3Frss%3Dyes Abstract: Kin recognition is an essential component of kin-directed adaptive behavior. Consequently, potential mechanisms of kin recognition, such as learning a kin phenotype from family members (familial imprinting) or self (self-referential phenotype matching), have been the focus of much research. Studies using computer-manipulated self-resemblance show effects for both same-sex and opposite-sex faces and have been interpreted as evidence for self-referential phenotype matching. However, more recent research on sex-contingent face processing suggests that visual experience with faces of one sex has little influence on perceptions of faces of the other sex, calling into question how self-referential phenotype matching can influence perceptions of opposite-sex faces. Because children rese... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256057 Tue, 14 Dec 2010 14:10:26 +0100 4256057 http://www.medworm.com/index.php?rid=4256053&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001029%2Fabstract%3Frss%3Dyes Abstract: Ethnographic, historical, archaeological and experimental work suggests the existence of two basic clusters of ritual dynamics or ‘modes of religiosity’ — a low-frequency, high-arousal cluster linked to the formation of small cohesive communities (imagistic mode) and high-frequency, low-arousal cluster associated with larger, more centralized social morphology (doctrinal mode). Currently, however, we lack a large-scale survey of ritual variation on which to test such predictions. Here, we compile data on 645 religious rituals from 74 cultures around the globe, extracted from the Human Relations Area Files, revealing that the cultural morphospace of ritual form favours rituals that are indeed either low-frequency and highly dysphorically arousing or high-frequency with lower... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256053 Tue, 14 Dec 2010 14:10:23 +0100 4256053 http://www.medworm.com/index.php?rid=4256049&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001017%2Fabstract%3Frss%3Dyes Abstract: Consciousness and self-awareness, juxtaposed by the ability to self-deceive, are legacies of our evolutionary heritage. As a purposive outgrowth of modularity, self-deception may serve to isolate threatening thoughts from consciousness and facilitate cooperation. The primary goal of the present investigation was to determine if individuals with depression exhibit both low levels of self-deception and cooperation. Relationships between the tendency to self-deceive and the conscious attributions typical of depression or promoting cooperation were also examined. Eighty undergraduate participants completed measures of self-deception, impression management, depression, and attributional styles. Cooperation was assessed by responses to social dilemmas based on the prisoner's dilemma ga... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256049 Tue, 14 Dec 2010 14:10:18 +0100 4256049 http://www.medworm.com/index.php?rid=4256045&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000772%2Fabstract%3Frss%3Dyes Abstract: According to error management theory (EMT) [Haselton M.G., & Buss D.M. (2000). Error management theory: a new perspective on biases in cross-sex mind reading. Journal of Personality and Social Psychology, 78, 81–91], evolved psychological mechanisms can lead to systematic cognitive errors whenever costs of false-positive and false-negative decisions have been asymmetrical over evolutionary history. In a courtship context, sex differences in reading commitment intent in a potential partner seem to be a result of these psychological mechanisms. EMT predicts a bias in women toward underperception of men's commitment intentions. Haselton and Buss found evidence for a commitment–skepticism bias in studies testing young women. These findings have not been replicated yet in the publ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256045 Tue, 14 Dec 2010 14:10:14 +0100 4256045 http://www.medworm.com/index.php?rid=4728606&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000966%2Fabstract%3Frss%3Dyes Abstract: Evolutionary theory predicts that kin relations will be distinct from friendships, but recent studies have suggested a degree of similarity between these two types of relationships. In this longitudinal study, we examined the influence of kinship on the maintenance costs of social relationships. We followed 25 students over an 18-month period as they made the transition from school to university and examined the association between kinship, relationship maintenance and decay. The emotional intensity of friendships, in comparison to kin relations, was more sensitive to decreases in contact frequency and more sensitive to decreases in the number of activities done together. These results demonstrate that important differences between kin relations and friendships emerge when the re... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728606 Thu, 09 Dec 2010 00:00:00 +0100 4728606 http://www.medworm.com/index.php?rid=4728604&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810001224%2Fabstract%3Frss%3Dyes Abstract: Laboratory studies have shown that images of eyes can cause people to behave more cooperatively in some economic games, and in a previous experiment, we found that eye images increased the level of contributions to an honesty box. However, the generality and robustness of the eyes effect is not known. Here, we extended our research on the effects of eye images on cooperative behavior to a novel context—littering behavior in a university cafeteria—and attempted to elucidate the mechanism by which they work, by displaying them both in conjunction with, and not associated with, verbal messages to clear one's litter. We found a halving of the odds of littering in the presence of posters featuring eyes, as compared to posters featuring flowers. This effect was independent of wheth... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728604 Mon, 06 Dec 2010 00:00:00 +0100 4728604 http://www.medworm.com/index.php?rid=4728602&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000942%2Fabstract%3Frss%3Dyes Abstract: There is a wide variation in the external eye morphology across species in primates, which is considered to reflect adaptation to ecological factors such as body size and habitat type. However, little attention has been paid to the contribution of social factors to the evolution of primate eye morphology. To explore this, we analyzed correlations among eye morphology, social factors (neocortex ratio and group size) and other factors (habitat type and body mass) in 30 living primate species including humans, using phylogenetically independent contrasts. The results indicated that parameters of primate eye morphology correlate with group size and neocortex ratio (Study 1). Further analysis of behavior indicated that the proportion of scanning with eyeball movement alone per total s... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4728602 Mon, 06 Dec 2010 00:00:00 +0100 4728602 http://www.medworm.com/index.php?rid=4467495&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000954%2Fabstract%3Frss%3Dyes Abstract: We tested the hypothesis that men are particularly sensitive to individual differences in the attractiveness of women of the same mate value as themselves and less sensitive to variation among women of lower or higher mate value. We first assessed sensitivity to variation in women's attractiveness by asking men (n=148) to choose the more attractive of two photographs of the same target woman (n=116), photographed once at ovulation, when estrogen—a hormone that has been found to increase women's attractiveness—is known to be high, and once during a nonfertile phase of the cycle. Across all women, men did not rate the picture of the ovulating woman as more attractive (p>.10), but they did rate this picture as more attractive for women of similar mate value to themselves. When w... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467495 Fri, 03 Dec 2010 00:00:00 +0100 4467495 http://www.medworm.com/index.php?rid=4467494&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381000098X%2Fabstract%3Frss%3Dyes Abstract: Women's mate selection criteria can be expected to include a preference for men who can protect them and their offspring. However, aggressive dominance and physical formidability are not an unalloyed good in a partner; as such, men are likely to be coercive toward their mates. Accordingly, because of the potential costs of living with an aggressively dominant and physically formidable mate, a woman's preferences in this regard can be expected to vary as a function of the appraisal of her vulnerability to aggression — the more that a woman sees herself as potentially benefiting from protection, the more that she can be expected to favor aggressive dominance and physical formidability in a mate. Across three Internet-based studies of US women, we found evidence consistent with th... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467494 Fri, 03 Dec 2010 00:00:00 +0100 4467494 http://www.medworm.com/index.php?rid=4467492&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000978%2Fabstract%3Frss%3Dyes Abstract: People are motivated to self-present to their potential romantic partners. We hypothesized that due to the uncertainty of paternity, one of the self-presentational behaviors that human females engage in when they are motivated to attract a long-term mate is designed to communicate to prospective partners that they are likely to be faithful. In Study 1, we show that females in a long-term-romance mindset are less likely to agree to going to a concert with another female known to be unfaithful (cheater) than with a female known to have many sexual partners (player) or a non-flirtatious control female (control). Females in the long-term-romance mindset are also less willing to be the unfaithful female's friend and less willing to indicate that she is similar to them. In Study 2, we ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467492 Fri, 03 Dec 2010 00:00:00 +0100 4467492 http://www.medworm.com/index.php?rid=4467490&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000991%2Fabstract%3Frss%3Dyes Abstract: Due to tradeoffs between mating and parental effort, men who pay child support to children from previous unions should be less likely to have subsequent children or to remarry than men who do not pay child support. I evaluate this prediction using data from the Panel Study of Income Dynamics (PSID), a nationally representative sample of American households. As predicted, child support payment is associated with lower probability of subsequent birth. However, the prediction was not met for marriage: men who paid child support were more, rather than less, likely to remarry. One interpretation of this result is that child support payment is an honest signal of men's willingness to commit to parental investment: by continuing to pay child support, men signal to prospective mates that... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4467490 Fri, 03 Dec 2010 00:00:00 +0100 4467490 http://www.medworm.com/index.php?rid=4907298&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000905%2Fabstract%3Frss%3Dyes Abstract: The occurrence of cooperation poses a problem for the biological and social sciences. However, many aspects of the biological and social science literatures on this subject have developed relatively independently, with a lack of interaction. This has led to a number of misunderstandings with regard to how natural selection operates and the conditions under which cooperation can be favoured. Our aim here is to provide an accessible overview of social evolution theory and the evolutionary work on cooperation, emphasising common misconceptions. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4907298 Wed, 10 Nov 2010 00:00:00 +0100 4907298 http://www.medworm.com/index.php?rid=4256043&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000747%2Fabstract%3Frss%3Dyes Abstract: Current research increasingly suggests that spatial cognition in humans is accomplished by many specialized mechanisms, each designed to solve a particular adaptive problem. A major adaptive problem for our hominin ancestors, particularly females, was the need to efficiently gather immobile foods which could vary greatly in quality, quantity, spatial location and temporal availability. We propose a cognitive model of a navigational gathering adaptation in humans and test its predictions in samples from the US and Japan. Our results are uniformly supportive: the human mind appears equipped with a navigational gathering adaptation that encodes the location of gatherable foods into spatial memory. This mechanism appears to be chronically active in women and activated under explicit ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256043 Mon, 08 Nov 2010 00:00:00 +0100 4256043 http://www.medworm.com/index.php?rid=4907300&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000784%2Fabstract%3Frss%3Dyes Abstract: The evolution of parochial altruism is not well understood. We study this problem by considering a prisoner's dilemma game with four strategies: altruists who cooperate with everyone; parochialists who only cooperate with members of their own group; traitors who only cooperate with outgroup individuals; and egoists who never cooperate. We develop a model that allows for both assortment and conflict between groups. Individuals discriminate between in- and outgroup members. While assortment and conflict allow for the evolution of both indiscriminate and parochial altruism, discriminate behavior creates an advantage for parochialists over altruists, as the latter waste help on outgroup members. We use computer simulations to study the multilevel selection dynamics. The simulation mo... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4907300 Mon, 01 Nov 2010 00:00:00 +0100 4907300 http://www.medworm.com/index.php?rid=4256055&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000735%2Fabstract%3Frss%3Dyes Abstract: The May 12, 2008, Chinese earthquake of 8.0 magnitude on the Richter scale placed residents in devastated areas in a disadvantaged position. We conducted three sequential surveys in both devastated and non-devastated areas to test our hypothesis that residential devastation would evoke more prosocial behavior. As expected, the results revealed that the degree of prosocial behavior increased with an increasing level of residential devastation, but decreased with the passage of time. However, we also found evidence that a catastrophic disaster leaves a long-lasting effect on prosocial behavior. These findings should improve the conceptual understanding of the origin of prosocial behavior. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256055 Mon, 01 Nov 2010 00:00:00 +0100 4256055 http://www.medworm.com/index.php?rid=4256051&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000899%2Fabstract%3Frss%3Dyes Abstract: Reputation monitoring and the punishment of cheats are thought to be crucial to the viability and maintenance of human cooperation in large groups of non-kin. However, since the cost of policing moral norms must fall to those in the group, policing is itself a public good subject to exploitation by free riders. Recently, it has been suggested that belief in supernatural monitoring and punishment may discourage individuals from violating established moral norms and so facilitate human cooperation. Here we use cross-cultural survey data from a global sample of 87 countries to show that beliefs about two related sources of supernatural monitoring and punishment — God and the afterlife — independently predict respondents' assessment of the justifiability of a range of moral trans... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256051 Mon, 01 Nov 2010 00:00:00 +0100 4256051 http://www.medworm.com/index.php?rid=4256047&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000760%2Fabstract%3Frss%3Dyes Abstract: In addition to triggering appropriate physiological activity and behavioural responses, emotions and moods can have an important role in decision making. Anxiety, for example, arises in potentially dangerous situations and can bias people to judge many stimuli as more threatening. Here, we investigated the possibility that affective states may also influence the time taken to make such judgements. Participants completed the Positive and Negative Affect Schedule (PANAS) mood inventory [Watson, D., Clark, L.A., Tellegen, A. Development and validation of brief measures of positive and negative affect: the PANAS scales. J Pers Soc Psychol, 54 (1988) 1063–1070] and undertook a computer-based task in which they were required to decide whether ambiguous and unambiguous predictor stimu... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256047 Mon, 01 Nov 2010 00:00:00 +0100 4256047 http://www.medworm.com/index.php?rid=4054612&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000759%2Fabstract%3Frss%3Dyes This study investigated the primary conclusion from Clark and Hatfield's often cited field experiment “Consent to Sex with a Stranger” that men agree to sexual invitations from moderately attractive strangers of the opposite gender more readily than women do. In addition, this study investigated whether rates of consent are influenced by a subject's age, relationship status, rating of confederate attractiveness, and type of sexual invitation. A number of moderately attractive confederates of the opposite gender individually approached 173 men and 216 women. After a standard introduction, the confederates asked each participant one of the following three questions: “Would you go on a date with me tonight or during the week/weekend?”, “Would you come to my place tonight or during t... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054612 Mon, 11 Oct 2010 14:40:26 +0100 4054612 http://www.medworm.com/index.php?rid=4054611&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000723%2Fabstract%3Frss%3Dyes We examined the trade-off from two perspectives using a representative sample of married South Korean women aged 20–44 in 2005 (n=977). First, paternal investment in domestic labor, including child care and housework, was expected to be associated with women's preference regarding future reproduction. Second, relative paternal investment was expected to increase women's preference for future reproduction, especially among employed women. We found that increased paternal investment in child care and housework remarkably enhanced women's intention to have a second child, especially among employed women. In addition, although family members provide a low percentage of child care in South Korea, such help is likely to be a useful resource for second childbirth among employed women. Somewhat ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054611 Mon, 27 Sep 2010 23:00:00 +0100 4054611 http://www.medworm.com/index.php?rid=4054610&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000711%2Fabstract%3Frss%3Dyes Abstract: The current study examined whether or not individuals who vicariously win a competition seek out pornography relatively more often than individuals who vicariously lose a competition. By examining a portion of Google keyword searches during the 2004, 2006 and 2008 US election cycles, the relative popularity of online pornography keywords searches was computed for each state and the District of Columbia the week before and the week after each election. Consistent with the Challenge Hypothesis, following all three election cycles, individuals located in states voting for the winning political party tended to search for pornography keywords relatively more often than individuals residing in states voting for the losing political party. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054610 Mon, 27 Sep 2010 23:00:00 +0100 4054610 http://www.medworm.com/index.php?rid=4054606&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000504%2Fabstract%3Frss%3Dyes Abstract: Research over the past decade has documented clear, robust changes in women's sexual preferences and interests across the ovarian cycle. When fertile, women are particularly attracted to a number of masculine male features (e.g., masculine faces, voices, scents and bodies) and other traits, and especially when they evaluate men's “sexiness” rather than their attractiveness as long-term partners. The current research extended this line of research by examining changes in women's self-reported sexual interests across the cycle. We asked 68 normally ovulating women in committed romantic relationships to fill out questionnaires about their sexual preferences and interests (at that time, not in general) twice across their cycles: once when fertile and once during the luteal phase.... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054606 Mon, 27 Sep 2010 23:00:00 +0100 4054606 http://www.medworm.com/index.php?rid=4054608&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000693%2Fabstract%3Frss%3Dyes This study investigates the fitness consequences of pre-reproductive school performance in a Swedish population-based cohort of 5244 males and 4863 females born 1915-1929. School performance was measured at around age 10 using three variables: mean school marks, being promoted/held back in school, and recognised learning difficulties. Our primary outcomes were probability of ever marrying, total number of children and total number of grandchildren. In males (but not females), poorer school performance predicted fewer children and grandchildren. This was primarily mediated via probability of marriage; mortality and fertility within marriage were not important mediating pathways. The effect of school performance upon marriage in males was independent of early-life social and biological chara... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054608 Tue, 31 Aug 2010 23:00:00 +0100 4054608 http://www.medworm.com/index.php?rid=4054609&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381000070X%2Fabstract%3Frss%3Dyes Abstract: Deviations from perfect symmetry in paired traits of otherwise bilateral symmetrical organisms are thought to reflect developmental quality, especially the ability to resist environmental perturbations early in ontogeny. It is well established that poor environmental conditions increase developmental instability (DI) as reflected by measurements of fluctuating asymmetry. In humans, there is evidence that DI relates to numerous fitness components, and studies have found that perceptions of facial attractiveness for example are positively correlated with measurements of facial symmetry. Here we report the data on measurements of facial symmetry of 503 Turkish senior year high school students aged 17 to 18 years, of whom 133 males and 117 females were recruited from a slum district ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054609 Sun, 29 Aug 2010 23:00:00 +0100 4054609 http://www.medworm.com/index.php?rid=4054607&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000681%2Fabstract%3Frss%3Dyes Abstract: A substantial body of work demonstrates that women's mate preferences change across the ovulatory cycle. When fertile in their cycles, women are especially attracted to masculine features (e.g., faces, voices, bodies), socially dominant behavior, and male scents associated with body symmetry and social dominance. Women may also find intelligent men particularly attractive when fertile, though findings are mixed. Related research shows that, on average, romantically-involved women report stronger sexual attraction to men other than their pair-bond partners, but not partners, when fertile, and especially when their partners lack features fertile women prefer (e.g., symmetry). In the current study, we examined whether women's patterns of sexual interests across the cycle are similar... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054607 Sun, 29 Aug 2010 23:00:00 +0100 4054607 http://www.medworm.com/index.php?rid=4054605&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000498%2Fabstract%3Frss%3Dyes Abstract: Research shows that women more positively evaluate targets evincing cues of high male genetic quality as a function of fertility across the menstrual cycle. Recently, a link between fertility and anti-black race bias has also been documented, an effect that is argued to serve a sexual coercion avoidance function. Here we demonstrate that both effects can be operative toward the same male target depending on inter-individual differences in race perception of the target. Across two studies, we found that the intention to vote for Barack Obama in the months preceding the 2008 election increased as a function of conception risk across the menstrual cycle. In the second study, we found that the effect is greatest among women who perceived him as more white than black, whereas the oppo... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054605 Thu, 22 Jul 2010 23:00:00 +0100 4054605 http://www.medworm.com/index.php?rid=3863957&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000516%2Fabstract%3Frss%3Dyes Abstract: Restrictive eating attitudes and behaviors have been hypothesized to be related to processes of intrasexual competition. According to this perspective, within-sex competition for status serves the adaptive purpose of attracting mates. As such, status competition salience may lead to concerns of mating desirability. For heterosexual women and gay men, such concerns revolve around appearing youthful and, thus, thinner. Following this logic, we examined how exposure to high-status and competitive (but not thin or highly attractive) same-sex individuals would influence body image and eating attitudes in heterosexual and in gay/lesbian individuals. Results indicated that for heterosexuals, intrasexual competition cues led to greater body image dissatisfaction and more restrictive eati... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863957 Thu, 22 Jul 2010 23:00:00 +0100 3863957 http://www.medworm.com/index.php?rid=4256059&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000450%2Fabstract%3Frss%3Dyes At its best, philosophy provides the theories that empirical scientists test and critically evaluates the results of their work: it is the conceptual wing of the natural sciences. At its worst, it has a reputation for getting itself tangled up in language games, introducing concepts and arguments that serve more to muddle than to clarify. In its finer moments, Jerry Fodor and Massimo Piatelli-Palmarini's (hereafter, FPP) new book, What Darwin Got Wrong, is an example of the first kind of philosophy (). It provides the kind of cautionary note that seems all the rage amongst philosophers writing about “Darwinism” at the moment: a scolding to those of us who are perceived as running amok in the playground of adaptationist explanation (e.g., ). While I happen to find most of these scolding... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4256059 Fri, 09 Jul 2010 00:00:00 +0100 4256059 http://www.medworm.com/index.php?rid=4054604&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000486%2Fabstract%3Frss%3Dyes This study accessed minimum (youngest age considered) and maximum (oldest age considered) age preferences from 14 separate cultures and two religious groups from both sexes at ages 20, 25, 30, 35, 40, 45, and 50 years. The results showed that overall there was a growing disparity between males own age and preferred age of partner as males themselves aged (as indicated by greater effect sizes with advertisers age), with females showing a pattern for preferences around their own age or older. Females did not express an age preference for males younger than male's age preferences for females at any advertiser's age. On only three occasions were there no age differences between the sexes in their desire to initiate a relationship with the opposite sex. The results were clearly concurrent with ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054604 Thu, 08 Jul 2010 23:00:00 +0100 4054604 http://www.medworm.com/index.php?rid=3863956&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000462%2Fabstract%3Frss%3Dyes Abstract: Humans are the only primates that make music. But the evolutionary origins and functions of music are unclear. Given that in traditional cultures music making and dancing are often integral parts of important group ceremonies such as initiation rites, weddings or preparations for battle, one hypothesis is that music evolved into a tool that fosters social bonding and group cohesion, ultimately increasing prosocial in-group behavior and cooperation. Here we provide support for this hypothesis by showing that joint music making among 4-year-old children increases subsequent spontaneous cooperative and helpful behavior, relative to a carefully matched control condition with the same level of social and linguistic interaction but no music. Among other functional mechanisms, we propos... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863956 Thu, 08 Jul 2010 23:00:00 +0100 3863956 http://www.medworm.com/index.php?rid=3863951&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000474%2Fabstract%3Frss%3Dyes Abstract: Error management theory is a theory of considerable scope and emerging influence. The theory claims that cognitive biases do not necessarily reflect flaws in evolutionary design, but that they may be best conceived as design features. Unfortunately, existing accounts are vague with respect to the key concept of bias. The result is that it is unclear that the cognitive biases that the theory seeks to defend are not simply a form of behavioral bias, in which case the theory reduces to a version of expected utility theory. We propose some clarifications and refinements of error management theory by emphasizing important distinctions between different forms of behavioral and cognitive bias. We also highlight a key assumption, that the capacity for Bayesian beliefs is subject to const... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863951 Thu, 08 Jul 2010 23:00:00 +0100 3863951 http://www.medworm.com/index.php?rid=3863958&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000413%2Fabstract%3Frss%3Dyes Abstract: Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The kin selection hypothesis for male androphilia suggests that androphilic males have been selected to act as “helpers-in-the-nest,” caring for nieces and nephews and, by extension, increasing their indirect fitness. Previous research has demonstrated that Samoan male androphiles (known locally as fa'afafine) exhibit significantly higher altruistic tendencies toward nieces and nephews compared to Samoan women and gynephilic men. Elevated avuncular tendencies must translate into real-world avuncular behavior if they are to have any impact on the fitness of nieces and nephews and the uncles themselves. The present study examined wheth... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863958 Tue, 22 Jun 2010 23:00:00 +0100 3863958 http://www.medworm.com/index.php?rid=3863955&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000425%2Fabstract%3Frss%3Dyes Abstract: Studies of physical attractiveness have long emphasized the constituent features that make faces and bodies attractive, such as symmetry, skin texture, and waist-to-hip ratio. Few studies, however, have examined the reproductively relevant cues conveyed by faces and bodies as whole units. Based on the premise that fertility cues are more readily assessed from a woman's body than her face, the present study tested the hypothesis that men evaluating a potential short-term mate would give higher priority to information gleaned from her body, relative to her face, than men evaluating a potential long-term mate. Male and female participants (N=375) were instructed to consider dating an opposite sex individual, whose face was occluded by a “face box” and whose body was occluded by ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863955 Tue, 22 Jun 2010 23:00:00 +0100 3863955 http://www.medworm.com/index.php?rid=3863953&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000292%2Fabstract%3Frss%3Dyes Abstract: Conformist social learning, the tendency to acquire the most common trait in a group, allows individuals to rapidly acquire established beneficial traits from a multitude of options. However, conformist strategies hinder acquisition of novel advantageous behavior patterns, because such innovations are by definition uncommon. This raises the possibility that proxy cues of the success of novel traits may be utilized to identify and acquire advantageous innovations and disregard failing options. We show that humans use changes in trait frequency over time as such a cue in an economic game. Participants played a three-alternative forced choice game (i.e., a multi-armed bandit), using social information to attempt to locate a high reward that could change location. Participants viewed... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863953 Sun, 20 Jun 2010 23:00:00 +0100 3863953 http://www.medworm.com/index.php?rid=3650915&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000309%2Fabstract%3Frss%3Dyes Abstract: The theory of biological markets and competitive altruism contends that competitive partner selection is favorable to the selection of prosocial behaviors in social evolution. The current study provides an empirical assessment of this theory based on a laboratory experiment with human subjects using the Ultimatum game. The experimental results show that more generous proposers and more tolerant responders are preferred as partners. This indicates that subjects tend to choose partners in a manner that coincides with their own interests. In competitive partner selection, partner preferences driven by self-interest nevertheless generate an assortative pairing structure that prompts players to behave fairly in the game. The study shows that a free market of partner selection, plus th... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650915 Fri, 11 Jun 2010 14:16:50 +0100 3650915 http://www.medworm.com/index.php?rid=3650912&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000280%2Fabstract%3Frss%3Dyes This article proposes that language — the uniquely human faculty of symbolic communication — fundamentally alters the possibilities for collective action. I explore these issues using simple game-theoretic models and empirical evidence (both ethnographic and experimental). I review several standard mechanisms for the evolution of cooperation — mutualism, reciprocal altruism, indirect reciprocity and signaling — highlighting their limitations when it comes to explaining large-group cooperation, as well as the ways in which language helps overcome those limitations. Language facilitates complex coordination and is essential for establishing norms governing production efforts and distribution of collective goods that motivate people to cooperate voluntarily in large groups. Language a... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650912 Fri, 11 Jun 2010 14:16:49 +0100 3650912 http://www.medworm.com/index.php?rid=3863954&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000267%2Fabstract%3Frss%3Dyes Discussion focuses on the implications of these findings for our understanding of the evolutionary origins of pride and social status, and the interrelations among emotion, personality, and status attainment. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863954 Sun, 09 May 2010 23:00:00 +0100 3863954 http://www.medworm.com/index.php?rid=3650917&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000255%2Fabstract%3Frss%3Dyes Abstract: Prosocial decisions may lead to unequal payoffs among group members. Although an aversion to inequity has been found in empirical studies of both human and nonhuman primates, the contexts previously studied typically do not involve a trade-off between prosociality and inequity. Here we investigate the apparent coexistence of these two factors, specifically the competing demands of prosociality and equity. We directly compare the responses of brown capuchin monkeys (Cebus apella) among situations where prosocial preferences conflict with equality, using a paradigm comparable to other studies of cooperation and inequity in this species. By choosing to pull a tray towards themselves, subjects rewarded themselves and/or another in conditions in which the partner either received the s... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650917 Tue, 04 May 2010 23:00:00 +0100 3650917 http://www.medworm.com/index.php?rid=3650916&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000243%2Fabstract%3Frss%3Dyes Abstract: Mounting evidence that cues of being watched can enhance cooperative behaviour questions the existence of ‘anonymous', one-shot, non-kin directed cooperation and the validity of using ‘anonymous' economic games to empirically measure such behaviour in humans. Here we investigate how sensitive people are to such cuing effects. We test whether people playing an ultimatum game can use explicit information about experimental anonymity to override any effects of cuing in a public context, when faced with both simultaneously. The aims of our study were to investigate whether, (1) individuals respond to experimentally imposed anonymity within a public context and (2) the presence of known others affects cooperative behaviour over and above merely the presence of others. We find that... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650916 Thu, 29 Apr 2010 23:00:00 +0100 3650916 http://www.medworm.com/index.php?rid=3863952&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000231%2Fabstract%3Frss%3Dyes Abstract: When searching for a mate, one must gather information to determine the mate value of potential partners. By focusing on individuals who have been previously chosen by others, one's selection of mates can be influenced by another's successful search—a phenomenon known as mate copying. We show mate copying in humans with a novel methodology that closely mimics behavioral studies with non-human animals. After observing instances of real mating interest in video recordings of speed-dates, both male and female participants show mate copying effects of heightened short-term and long-term relationship interest towards individuals in dates they perceived as successful. Furthermore, the relative attractiveness of observers and observed plays a mediating role in whom an individual will ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863952 Thu, 22 Apr 2010 23:00:00 +0100 3863952 http://www.medworm.com/index.php?rid=3485325&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000176%2Fabstract%3Frss%3Dyes Abstract: Although research indicates that individuals generally favor certain prospects over those whose outcomes are more variable, risk-aversion does not characterize human decision-making across domains. Here, we use an evolutionary perspective to explore the role that concerns with relative position play on preferences for certain versus probabilistic outcomes. Our evolutionary-based hypothesis predicts that concern with relative position will lead to increased risk when (1) the higher variance outcome offers the potential to render one better off than social competitors, but the lower variance outcome would not, (2) the choice is in a decision domain affecting one's ability to solve adaptive problems reliably present in human social life, and (3) the decision is being made about a ga... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485325 Tue, 20 Apr 2010 16:49:50 +0100 3485325 http://www.medworm.com/index.php?rid=3485319&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000889%2Fabstract%3Frss%3Dyes Abstract: In women of reproductive age, a gynoid body fat distribution as measured by the size of waist–hip ratio (WHR) is a reliable indicator of their sex hormone profile, greater success in pregnancy and less risk for major diseases. According to evolutionary mate selection theory, such indicators of health and fertility should be judged as attractive. Previous research has confirmed this prediction. In this current research, we use the same stimulus for diverse racial groups (Bakossiland, Cameroon, Africa; Komodo Island, Indonesia; Samoa; and New Zealand) to examine the universality of relationships between WHR and attractiveness. As WHR is positively correlated with body mass index (BMI), we controlled BMI by using photographs of women who have gone through micrograft surgery for co... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485319 Tue, 20 Apr 2010 16:49:50 +0100 3485319 http://www.medworm.com/index.php?rid=3485318&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000279%2Fabstract%3Frss%3Dyes Abstract: Literature in evolutionary psychology suggests that mate choice has been the primary mechanism of sexual selection in humans, but this conclusion conforms neither to theoretical predictions nor available evidence. Contests override other mechanisms of sexual selection; that is, when individuals can exclude their competitors by force or threat of force, mate choice, sperm competition, and other mechanisms are impossible. Mates are easier to monopolize in two dimensional mating environments, such as land, than in three-dimensional environments, such as air, water, and trees. Thus, two-dimensional mating environments may tend to favor the evolution of contests. The two-dimensionality of the human mating environment, along with phylogeny, the spatial and temporal clustering of mates ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485318 Tue, 20 Apr 2010 16:49:49 +0100 3485318 http://www.medworm.com/index.php?rid=3863959&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051381000005X%2Fabstract%3Frss%3Dyes Hrdy's book begins with a beguiling example; imagine what a typical plane trip is like, then imagine what the trip would be like if we were any other species of ape (i.e., loud, violent and foul). This, she claims, is what really separates us from our closest living relatives; not that we can build the plane, but that we can behave ourselves on it. The ability (not just social but hypersocial) to read minds, empathize and tolerate is our distinguishing feature, and Hrdy's thesis is that it has its origins in the cooperative breeding habits of our ancestors. It is through cooperative breeding that we have diverged from the chimps (or the animals who became chimps) and emerged as emotionally modern humans, albeit long before we were modern in any other sense. (Source: Evolution and Human Beh... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3863959 Sun, 04 Apr 2010 23:00:00 +0100 3863959 http://www.medworm.com/index.php?rid=3650921&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000024%2Fabstract%3Frss%3Dyes In chess, a gambit is the sacrifice of material, usually pawns, in order to gain superior position. In evolutionary biology, the “phenotypic gambit” is the implicit assumption that genetic data can be sacrificed in testing evolutionary hypotheses because phenotypes adequately predict underlying genotypes (). Evolutionary psychologists often play a third gambit, which I will call the psychologic gambit. This is the implicit assumption that neurophysiological underpinnings can largely be ignored when testing evolutionary hypotheses about behavior and psychology. After all, if one is interested in the evolutionary functions of behavioral and psychological patterns, does it matter whether these patterns depend upon the nucleus accumbens or the basolateral amygdala, for example, or upon vas... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650921 Sun, 04 Apr 2010 23:00:00 +0100 3650921 http://www.medworm.com/index.php?rid=3650918&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000048%2Fabstract%3Frss%3Dyes Abstract: Some of the strongest evidence for sex differences in human cognition relate to spatial abilities, with men traditionally reported to outperform women. Recently, however, such differences have been shown to be task dependent. Supporting the argument that a critical factor selecting for sex differences in spatial abilities during human evolution is likely to have been the division of labor during the Pleistocene, evidence is accumulating that women excel on tasks appropriate to gathering immobile plant resources, while men excel on tasks appropriate to hunting mobile, unpredictable prey. Most research, with the exception of some recent experimental field studies, has been conducted in the laboratory, with little information available on how men and women actually forage under natu... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650918 Sun, 04 Apr 2010 23:00:00 +0100 3650918 http://www.medworm.com/index.php?rid=3650914&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513810000036%2Fabstract%3Frss%3Dyes Abstract: Third-party punishment for norm violators is an evolvable enforcer of social norms. The present study, involving two experiments, examined whether violations of honesty norms would induce costly third-party punishments. In both experiments, participants in the third-party role observed a protocol of the trust game, in which the trustee solicited the trustor to transfer his/her endowment by stating that the trustee would return x units from the total resource. Dishonesty was defined such that the trustee in fact returned fewer than x units. Participants were asked about their willingness to incur some cost to reduce the trustee's payoff. In Experiment 1, x was exactly half of the total resource. Participants were willing to incur more cost to punish the dishonest trustee than the ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650914 Fri, 26 Feb 2010 00:00:00 +0100 3650914 http://www.medworm.com/index.php?rid=4054613&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001330%2Fabstract%3Frss%3Dyes Richard Dawkins's The Greatest Show on Earth: The Evidence for Evolution is not only an elegant exposition of the evidence for the scientific fact of evolution, but also a clear and creative explanation of the theory, and the stumbling blocks to its proper understanding. Theory should not be confused with hypothesis, and Dawkins is adamant about referring to evolution as a fact. We agree with him. When scientists and evolutionary scholars refer to “evolutionary theory” among themselves, there is no need to explain that a scientific theory is a framework that describes and predicts processes in the physical world based on mutually supportive, empirical evidence. Outside of scientific circles, however, scientists should be cautious when using the term theory, because antiscientific inter... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=4054613 Wed, 24 Feb 2010 00:00:00 +0100 4054613 http://www.medworm.com/index.php?rid=3293330&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001317%2Fabstract%3Frss%3Dyes Pollet and Nettle (; henceforth, P&N) used ordinal regression models to investigate the effect of indicators of male quality, height and income, on self-reported female orgasm frequency. The strategy was as follows: in the first step the two key variables, male height and male income, were included. Subsequently, height was removed as it proved not to be a significant predictor at 5% level. Then, using an information theoretic approach, the authors examined whether model fit could be improved by adding control variables and stopped when the model could not be further improved as assessed by the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). P&N concluded that the best-fitting model contained partner income as a predictor. (Source: Evolution and Human Behav... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293330 Mon, 22 Feb 2010 15:45:51 +0100 3293330 http://www.medworm.com/index.php?rid=3293329&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000646%2Fabstract%3Frss%3Dyes In a recent article in this journal (Pollet and Nettle, 2009), we reported that women with higher-income partners reported more frequent orgasms in the data from the Chinese Health and Family Life Survey (CHFLS). We also reported, using a stepwise model selection strategy implemented in SPSS 15.0 (SPSS, Chicago, IL, USA), that partner income was a better predictor of reported orgasm frequency than a number of control variables. However, in an accompanying commentary, Herberich et al. show that the model-fit statistics produced in SPSS are not properly comparable between models. This led us to choose an incorrect model as the best-fitting one. As they show, the effect of partner income is no longer significant once the control variables have been accounted for. We therefore wish to correct ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293329 Mon, 22 Feb 2010 15:45:50 +0100 3293329 http://www.medworm.com/index.php?rid=3650920&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001305%2Fabstract%3Frss%3Dyes Glimpses of Creatures in Their Physical Worlds is a heart-pounding, heat-conducting, power-amplifying whirlwind tour through the mechanical and thermal worlds of Earth's living things. The journey has something for everyone: the thrills of explosively launched projectiles, the chills of supercooling polar fish, the rise of birds soaring on an ascending torus of ground-heated air. Along the way, there are insights into the functional analysis of biological systems, relevant not only to researchers in biomechanics but also to the broad community of scientists seeking to understand the workings of life's devices. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650920 Thu, 04 Feb 2010 00:00:00 +0100 3650920 http://www.medworm.com/index.php?rid=3650919&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051380900124X%2Fabstract%3Frss%3Dyes Abstract: A growing body of literature in evolutionary psychology suggests that person perception processes are adaptively tuned. The current investigation tested the hypothesis that people would be able to detect a propensity for violence in other people, based only on a brief glance at their face. Participants estimated the propensity for violence in 87 registered sex offenders after seeing photos of them for 2 s each. Estimated likelihood of violence was significantly related to actual violent history, suggesting that violent tendencies can be accurately inferred from a brief look at a person's face. Cues indicative of high masculinity and high levels of male sex hormones (heavy brow, general facial masculinity, high physical strength, younger age) were related to accurate judgments. Ot... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650919 Thu, 04 Feb 2010 00:00:00 +0100 3650919 http://www.medworm.com/index.php?rid=3650913&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001329%2Fabstract%3Frss%3Dyes This study found that cooperative labour investment is important for Saami reindeer herders, but that the effect of kinship and labour needs to be understood in relation to each other. When assessing the effect of labour and kinship simultaneously, both labour and genealogical relationship had positive effects on herd size. We also found a positive interaction between kinship and labour suggesting that high levels of relatedness coupled with a large potential labour pool had an increasingly positive effect on herd size. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3650913 Thu, 04 Feb 2010 00:00:00 +0100 3650913 http://www.medworm.com/index.php?rid=3485327&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001238%2Fabstract%3Frss%3Dyes Sex is serious business. It significantly affects most adults' quality of life and well-being, and can cement or fracture the most intimate of social relationships. Sexual stimuli are so effective at capturing people's attention that in my field of marketing they are used daily to encourage people to purchase an array of products and services such as computing servers, submarine sandwiches, toilet paper, many other things seemingly unrelated to sex. A Google search of the well-known phrase “sex sells” returns over 693,000 hits. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485327 Thu, 04 Feb 2010 00:00:00 +0100 3485327 http://www.medworm.com/index.php?rid=3077786&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001202%2Fabstract%3Frss%3Dyes Margo Ings Wilson, Professor of Psychology (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077786 Fri, 11 Dec 2009 14:59:13 +0100 3077786 http://www.medworm.com/index.php?rid=3293327&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000853%2Fabstract%3Frss%3Dyes Abstract: The Wason selection task, a standard test of conditional reasoning, has featured prominently in experimental studies of cognitive adaptations for cooperation. The most prominent of these is Cosmides' investigations of cheater detection on social contract versions of the Wason selection task [Cognition 31 (1989) 187–276]. Subsequent to Cosmides' initial investigations, several researchers [Evol Hum Behav 21 (200) 25–37; Manage Decis Econ 19 (1998) 467–480; J Genet Psychol 163 (2002) 425–444; Evol Hum Behav 27 (2006) 366–380] have argued that people also are competent at detecting altruism on the Wason selection task, suggesting that there is nothing privileged about the detection of cheaters. However, an analysis of the selection tasks on which these claims are based sug... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293327 Fri, 11 Dec 2009 00:00:00 +0100 3293327 http://www.medworm.com/index.php?rid=3485326&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001068%2Fabstract%3Frss%3Dyes In Spent, Geoff Miller brings an evolutionary perspective to consumer behavior in modern industrialized societies. The puzzle is the empty and energetic pursuit of materialistic goals. Why do we work so hard to buy goods and services that rarely produce lasting satisfaction? (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485326 Wed, 09 Dec 2009 00:00:00 +0100 3485326 http://www.medworm.com/index.php?rid=3485320&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001093%2Fabstract%3Frss%3Dyes We report evidence showing that congenitally blind men, without previous visual experience, exhibit a preference for low female WHRs when assessing female body shapes through touch, as do their sighted counterparts. This finding shows that a preference for low WHR can develop in the complete absence of visual input and, hence, that such input is not necessary for the preference to develop. However, the strength of the preference was greater for the sighted than the blind men, suggesting that visual input might play a role in reinforcing the preference. These results have implications for debates concerning the evolutionary and developmental origins of human mate preferences, in particular, regarding the role of visual media in shaping such preferences. (Source: Evolution and Human Behaviou... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485320 Wed, 09 Dec 2009 00:00:00 +0100 3485320 http://www.medworm.com/index.php?rid=3485322&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051380900107X%2Fabstract%3Frss%3Dyes This study investigated male attractiveness rankings in a small-scale Amazonian society. In the rural community of Conambo, Ecuador, men and women practice self-sufficient horticulture, men hunt, and, traditionally, men have experienced a high rate of mortality due to homicide. We tested whether male attractiveness rankings would be related to male age, warriorship, hunting ability, status, coalitional affiliation, and female age. Twenty-five women aged between 14 and 78 years ranked photographs of 29 local men aged between 16 and 74 years for attractiveness in addition to warriorship, hunting ability, and status. Results revealed that male age was negatively correlated (r=−.683, p=.01) with female rankings of male attractiveness. Warriorship (r=.517, p=.005), status (r=.489, p=.008), an... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485322 Wed, 02 Dec 2009 00:00:00 +0100 3485322 http://www.medworm.com/index.php?rid=3485321&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809001081%2Fabstract%3Frss%3Dyes Abstract: Tattoos and non-conventional piercings are used in many societies. There are several social reasons for which people use these forms of body decorations (e.g., marking social status or signaling membership within a subculture). However, it is interesting why only some people within a group that uses body decoration as a badge of membership decide upon such decorations. Since both tattoos and piercings can present health risks (e.g., due to blood-borne disease transmission risk), we postulate that people who decide to have such a body decoration might have relatively higher biological quality and that tattoos/piercings can be an honest signal of genetic quality. The possible opposite hypothesis is the “attractiveness increase hypothesis,” according to which people use body dec... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485321 Wed, 02 Dec 2009 00:00:00 +0100 3485321 http://www.medworm.com/index.php?rid=3293324&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000919%2Fabstract%3Frss%3Dyes Abstract: To test the hypothesis that sensitivity to monitoring drives people to act altruistically toward members of their own community, two experiments investigated whether an eye-like painting promotes altruism toward in-group members, but not toward out-group members. Participants played the role of dictator in a dictator game with another participant (a recipient) who was from the minimal in-group or out-group. Participants knew whether their recipient was an in-group member or an out-group member, but were informed that their recipient did not know the group membership of the dictator. In-group favoritism occurred only when participants were facing a computer desktop which displayed a painting of eyes, but did not occur in the absence of eyes. These findings demonstrate that the eye... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293324 Wed, 02 Dec 2009 00:00:00 +0100 3293324 http://www.medworm.com/index.php?rid=3077787&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000890%2Fabstract%3Frss%3Dyes In this study, we investigate in a real-life situation, whether (1) the perception of child facial resemblance and (2) the likelihood of parental investment were predicted by actual facial resemblance to self, for both parents. The actual facial resemblance of 79 French children was quantified by testing external judges. Data on ascription of resemblance and parental investment were collected in private for each parent. First, ascription of facial resemblance was found to be consistent between the two parents and to match actual resemblance to the father. Second, emotional closeness as reported by fathers, but not by mothers, was found to be predicted by actual facial resemblance to self. This suggests that paternity uncertainty has favored the use of facial phenotype matching in fathers. ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077787 Thu, 19 Nov 2009 00:00:00 +0100 3077787 http://www.medworm.com/index.php?rid=3077794&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000907%2Fabstract%3Frss%3Dyes Abstract: Because women's preferences for male masculinity reflect tradeoffs between the benefits of greater genetic health and the costs of lower paternal investment, variables that affect the importance of these costs and benefits also affect masculinity preferences. Concern about disease and pathogens may be one such variable. Here we show that disgust sensitivity in the pathogen domain is positively correlated with facial masculinity preferences, but disgust sensitivity in the moral and sexual domains is not. Our findings present novel evidence that systematic variation in women's preferences for masculine men reflects factors that influence how women resolve the tradeoff between the benefits and costs associated with choosing a masculine partner. (Source: Evolution and Human Behaviour... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077794 Wed, 18 Nov 2009 00:00:00 +0100 3077794 http://www.medworm.com/index.php?rid=3293325&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000877%2Fabstract%3Frss%3Dyes Abstract: Several studies have indicated that people are able to memorize the face of a cheater more accurately than that of a noncheater, but some contradictory findings have also been reported. Because most previous studies focused on memory for the faces of cheaters who break social contracts, the consequence for the subjects of their cheating was unclear. In our study, participants were asked to decide whether they trusted persons depicted in photographs to give them money using two sessions of the Faith Game. The participants tended to not increase their trust in the individuals, depicted in photographs, who had altruistically given money to them previously. However, participants recognized nonaltruists who had not shared money and, during the second session, rescinded the trust that ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293325 Mon, 16 Nov 2009 00:00:00 +0100 3293325 http://www.medworm.com/index.php?rid=3293326&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000841%2Fabstract%3Frss%3Dyes Abstract: Theoretical work predicts that individuals should strategically increase their reliance on social learning when individual learning would be costly or risky, or when the payoffs for individually learned behaviors are uncertain. Using a method known to elicit cumulative cultural evolution in the laboratory, we investigated the degree of within-group similarity, and between-group variation, in design choices made by participants under conditions of varying uncertainty about the likely effectiveness of those designs. Participants were required to build a tower from spaghetti and modeling clay, their goal being to build the tower as high as possible. In one condition, towers were measured immediately on completion and, therefore, participants were able to judge the success of their d... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293326 Mon, 09 Nov 2009 00:00:00 +0100 3293326 http://www.medworm.com/index.php?rid=3293321&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000932%2Fabstract%3Frss%3Dyes In this study, we defined cooperators and non-cooperators in terms of their behavior as the proposer in an ultimatum game, and video-taped their facial expressions as they faced unfair offers as a responder. A detailed analysis of the facial expressions displayed by participants revealed that cooperators displayed greater amounts of emotional expressions, not limited to positive emotional expression, when responding to unfair offers in the ultimatum game. These results suggest that cooperators may be more emotionally expressive than non-cooperators. We speculate that emotional expressivity can be a more reliable signal of cooperativeness than the display of positive emotion alone. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293321 Mon, 09 Nov 2009 00:00:00 +0100 3293321 http://www.medworm.com/index.php?rid=3077792&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051380900066X%2Fabstract%3Frss%3Dyes Abstract: It is clear that genes at the major histocompatibility complex (MHC) are involved in mate preferences in a range of species, including humans. However, many questions remain regarding the MHC's exact influence on mate preference in humans. Some research suggests that genetic dissimilarity and individual genetic diversity (heterozygosity) at the MHC influence mate preferences, but the evidence is often inconsistent across studies. In addition, it is not known whether apparent preferences for MHC dissimilarity are specific to the MHC or reflect a more general preference for genome-wide dissimilarity, and whether MHC-related preferences are dependent on the context of mate choice (e.g., when choosing a short-term and long-term partner). Here, we investigated whether preferences for ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077792 Mon, 26 Oct 2009 00:00:00 +0100 3077792 http://www.medworm.com/index.php?rid=3293322&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000695%2Fabstract%3Frss%3Dyes Abstract: In the present study, the costly signaling theory (CST) is used to examine the effect of an offer of charity on social recognition. On behalf of a charitable organization, 186 students enrolled in 16 different courses were asked to offer support to unfamiliar persons in need. In accordance with our predictions, the results show that significantly more subjects are willing to give assistance if they make charity offers in the presence of their group members than when the offers are made in secret. In accordance with CST—but not with the prevailing explanations in social psychology—the likelihood of charity service was strongly influenced by the expected cost of altruistic behavior. Publicly demonstrated altruistic intentions yielded long-term benefits: Subjects who were willin... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293322 Fri, 23 Oct 2009 00:00:00 +0100 3293322 http://www.medworm.com/index.php?rid=3077793&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000816%2Fabstract%3Frss%3Dyes Abstract: Evolutionary explanations of low fertility in modern affluent societies commonly state that low fertility is the outcome of high parental investments in the quality of their children. Although the empirical evidence that modern parents do face a quantity–quality trade-off is strong, two issues that are relevant from an evolutionary perspective have not received much attention. First, sex differences in the proximate aspects of quality have been largely ignored. Second, the relationship between the quantity of children and their reproductive success in contemporary low-fertility societies remains unclear. In this article, we study the quantity–quality trade-off as a trade-off between the number of children and the mate value and reproductive success of those children. We exami... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077793 Fri, 23 Oct 2009 00:00:00 +0100 3077793 http://www.medworm.com/index.php?rid=2882091&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000804%2Fabstract%3Frss%3Dyes With 2,400 years of hindsight, it seems unlikely that Plato's eternal, immutable Forms actually exist. No one believes, for example, that all chairs are merely shadows cast by a literal, eternal Chair, apprehensible only to the intellect. When it comes to living organisms, however, including Homo sapiens, Plato's concept of Forms still has some traction. Genes, like Forms, are more or less immutable and only indirectly perceptible, yet they appear to encode the essence of what it means to be a human. Because genes vary, they also raise the unsettling specter of distinct African, Asian, and European essences, or natures, a specter that has hobbled investigation of the genetic basis of human behavior for decades. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882091 Mon, 12 Oct 2009 14:03:51 +0100 2882091 http://www.medworm.com/index.php?rid=3293328&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000683%2Fabstract%3Frss%3Dyes This study tests the folk psychological belief that we find things funny because we think they are true. Specifically, it addresses the relationship between implicit preferences and laughter. Fifty-nine undergraduate Rutgers University students (33 females and 26 males) from ethnically diverse backgrounds were videotaped while watching a white stand-up comedian for 30 min. Positive emotional expression associated with laughter was later scored using the facial action coding system (FACS). Computer-timed Implicit Association Tests (IATs) were used to measure a subject's implicit preferences for traditional gender roles and racial preferences (blacks vs. whites). Results show that participants laughed more in response to jokes that matched their implicit preferences (e.g., those with stronge... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293328 Mon, 05 Oct 2009 00:00:00 +0100 3293328 http://www.medworm.com/index.php?rid=3293331&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000865%2Fabstract%3Frss%3Dyes It seems these days that female sexuality is one of the hot topics, whether you are a psychologist, biologist, sex researcher, anthropologist, sociologist or feminist. A plethora of books (both academic and popular press) have been published from The Secrets of Female Sexuality: Unapologetic Brutally Honest Truth About Sex That Women Secretly Wish You Knew But Can't Tell You (2007) by David Shade to The Case of The Female Orgasm: Bias in the Science of Evolution (2006) by Elizabeth Lloyd to the soon-to-be-published Why Women Have Sex: Understanding Sexual Motivations From Adventure to Revenge (And Everything in Between) (2009) by Cindy Meston and David Buss. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293331 Tue, 22 Sep 2009 00:00:00 +0100 3293331 http://www.medworm.com/index.php?rid=3293323&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000701%2Fabstract%3Frss%3Dyes Abstract: Understanding the ultimate and proximate mechanisms that favour cooperation remains one of the greatest challenges in the biological and social sciences. A number of theoretical studies have suggested that competition between groups may have played a key role in the evolution of cooperation within human societies, and similar ideas have been discussed for other organisms, especially cooperative breeding vertebrates. However, there is a relative lack of empirical work testing these ideas. Our experiment found, in public goods games with humans, that when groups competed with other groups for financial rewards, individuals made larger contributions within their own groups. In such situations, participants were more likely to regard their group mates as collaborators rather than com... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293323 Wed, 16 Sep 2009 00:00:00 +0100 3293323 http://www.medworm.com/index.php?rid=3485323&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000671%2Fabstract%3Frss%3Dyes Abstract: For 14 teams of three young men, salivary testosterone and cortisol were assessed twice before and twice after competing in within-group and between-group video games that simulated violent male–male competition. Men who contributed the most to their teams' between-group victory showed testosterone increases immediately after the competition, but only if this competition was played before the within-group tournament. High-scoring men on losing teams did not show this immediate effect, but they did show a delayed increase in testosterone. In contrast, high-ranking men tended to have lower testosterone and higher cortisol during within-group tournaments. The results are consistent with the hypothesis that men's competitive testosterone response varies across ingroup and outgroup ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485323 Tue, 15 Sep 2009 23:00:00 +0100 3485323 http://www.medworm.com/index.php?rid=3077795&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS109051380900083X%2Fabstract%3Frss%3Dyes When we think of what behavior, if any, makes us distinctly human—of what do we think? One might be inclined to think of our ability to plan ahead or our complex language, religion, and culture. However, if we look at the most phylogenetically recent structure responsible for generating behavior, the cerebral cortex, we find that the vast majority of ours is dedicated to the interpretation of sensory information, the vast majority of which is dedicated to vision. Oddly, while we have books on the evolution of decision-making, language, religion, and culture, few books on the evolution of visual perception exist. The stated goal of The Vision Revolution is to explain the origin of select visual perception mechanisms. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077795 Fri, 11 Sep 2009 00:00:00 +0100 3077795 http://www.medworm.com/index.php?rid=3077789&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000592%2Fabstract%3Frss%3Dyes Abstract: Evidence across the social and behavioral sciences points to psychological mechanisms that facilitate the formation and maintenance of interpersonal commitment. In addition, evolutionary simulation studies suggest that a tendency for increased, seemingly irrational commitment is an important trait of successful exchange strategies. However, empirical research that tests corresponding psychological mechanisms is still largely lacking. Here an experimental test is proposed for one such mechanism, termed the commitment bias, which is hypothesized to increase people's commitment to existing partners beyond instrumental reasons. To exclude one alternative explanation, the commitment bias is distinguished from uncertainty reduction. Results from a cross-culturally replicated laboratory... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077789 Thu, 10 Sep 2009 00:00:00 +0100 3077789 http://www.medworm.com/index.php?rid=3485324&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000658%2Fabstract%3Frss%3Dyes Abstract: Cooperative behavior depends in part on a preference for equitable outcomes. Recent research in behavioral economics assesses variables that influence adult concerns for equity, but few studies to date investigate the emergence of equitable behavior in children using similar economic games. We tested 288 3- to 6-year olds in an anonymous Dictator Game to assess how the value of the currency used affects equity preferences in children. To manipulate value, children played the game with their most or least favorite stickers. At all ages, we found a strong value effect with children donating more of their least favorite stickers than their favorite stickers. We also found a dramatic increase with age in the percentage of children who were prosocial (i.e. donated at least one sticker... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3485324 Wed, 09 Sep 2009 23:00:00 +0100 3485324 http://www.medworm.com/index.php?rid=3293320&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000622%2Fabstract%3Frss%3Dyes In this study, we tested whether individuals are able to identify altruistic traits. Judges watched 20-s silent video clips of unacquainted target persons and were asked to estimate the behavior of these target persons in a money-sharing task. As the videotapes of the target persons had been recorded in a setting unrelated to altruistic behavior, the judges could not base their estimates on situational cues related to the money-sharing task but instead had to draw on stable signals of altruism. Estimates were significantly better than chance, indicating that individuals can identify permanent altruistic traits in others. As this mechanism raises opportunities for selective interactions between altruists, our findings are discussed with respect to their relevance for explaining the evolutio... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3293320 Wed, 09 Sep 2009 00:00:00 +0100 3293320 http://www.medworm.com/index.php?rid=3077790&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000610%2Fabstract%3Frss%3Dyes Abstract: Previous mate preference studies indicate that people prefer partners whose personalities are extremely kind and trustworthy, but relatively nondominant. This conclusion, however, is based on research that leaves unclear whether these traits describe the behavior a partner directs toward oneself, toward other classes of people or both. Because the fitness consequences of partners' behaviors likely differed depending on the classes of individuals toward whom behaviors were directed, we predicted that mate preferences for personality traits would change depending on the specific targets of a partner's behavioral acts. Consistent with this, two experiments demonstrated that people prefer partners who are extremely kind and trustworthy when considering behaviors directed toward thems... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077790 Wed, 09 Sep 2009 00:00:00 +0100 3077790 http://www.medworm.com/index.php?rid=3077791&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000634%2Fabstract%3Frss%3Dyes Abstract: Evidence from the anthropological record indicates that in most human societies, parents control the mating access to their offspring. Based on these data, a model of sexual selection has been recently proposed, whereby along with female and male choice, parental choice constitutes a significant sexual selection force in our species. This model was found to provide a good account for the mating patterns which are typical of foraging societies. By employing data from the Standard Cross Cultural Sample, the present study aims at examining whether this model can also account for the mating patterns typical of agricultural and pastoral societies. In addition, comparisons between different society types are made and two model-derived hypotheses are tested. First, it is hypothesised th... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077791 Mon, 07 Sep 2009 00:00:00 +0100 3077791 http://www.medworm.com/index.php?rid=2882090&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000609%2Fabstract%3Frss%3Dyes This study investigated sex-specific predictors of violent and nonviolent mate guarding used by men (n=399) and women (n=951) in heterosexual relationships, using both self-reports and reports on partners. We found, contrary to some previous evolutionary assumptions, that men and women showed similar degrees of controlling behavior, and that this predicted physical aggression to partners in both sexes. We also predicted from evolutionarily based studies that men's and women's control and aggression would vary as a function of female fecundity and mate value (relative to peer group and to partner). Fecundity was associated with men's and women's controlling behavior, but not their physical aggression: relationships where the woman was fecund showed higher rates of control. According to part... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882090 Sun, 06 Sep 2009 23:00:00 +0100 2882090 http://www.medworm.com/index.php?rid=2882089&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000555%2Fabstract%3Frss%3Dyes Abstract: Previous studies with adult humans and nonhuman animals revealed more rapid fear learning for spiders and snakes than for mushrooms and flowers. The current experiments tested whether 11-month-olds show a similar effect in learning associative pairings between facial emotions and fear-relevant and fear-irrelevant stimuli. Consistent with the greater incidence of snake and spider phobias in women, results show that female but not male infants learn rapidly to associate negative facial emotions with fear-relevant stimuli. No difference was found between the sexes for fear-irrelevant stimuli. The results are discussed in relation to fear learning, phobias, and a specialized evolved fear mechanism in humans. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882089 Sun, 16 Aug 2009 23:00:00 +0100 2882089 http://www.medworm.com/index.php?rid=2882086&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000580%2Fabstract%3Frss%3Dyes In this study, we assessed the relative importance of the face and body in judgments of human physical attractiveness. One hundred twenty-seven men and 133 women were shown images of 10 individuals of the opposite sex. Participants rated the images for their attractiveness for either a short-term relationship or a long-term relationship. Images of the face and the body were rated independently before participants were shown and asked to rate the combined face and body images. Face ratings were found to be the best predictor of the ratings of combined images for both sexes and for both relationship types. Females showed no difference in ratings between short- and long-term conditions, but male ratings of female bodies became relatively more important for a short-term relationship compared w... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882086 Sun, 16 Aug 2009 23:00:00 +0100 2882086 http://www.medworm.com/index.php?rid=2882085&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000579%2Fabstract%3Frss%3Dyes Abstract: Attractiveness judgments are thought to underpin adaptive mate choice decisions. We investigated how these judgments change during adolescence when mate choice is becoming relevant. Adolescents aged 11–15 evaluated faces and voices manipulated along dimensions that affect adults' judgments of attractiveness and that are thought to cue mate value. Facial stimuli consisted of pairs of faces that were more or less average, more or less feminine, or more or less symmetric. The adolescents selected the more average, symmetric, and feminine faces as more attractive more often than chance, but judgments of some facial traits differed significantly with rater age and sex, indicating a role of development in judgments of facial cues. Vocal stimuli consisted of pairs of voices manipulate... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882085 Sun, 16 Aug 2009 23:00:00 +0100 2882085 http://www.medworm.com/index.php?rid=2882084&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000567%2Fabstract%3Frss%3Dyes Abstract: Recent studies show that subtle cues of observation affect cooperation even when anonymity is explicitly assured. For instance, recent studies have shown that the presence of eyes increases cooperation on social economic tasks. Here, we tested the effects of cues of observation on trusting behavior in a two-player Trust game and the extent to which these effects are qualified by participants' own attractiveness. Although explicit cues of being observed (i.e., when participants were informed that the other player would see their face) tended to increase trusting behavior, this effect was qualified by the participants' other-rated attractiveness (estimated from third-party ratings of face photographs). Participants' own physical attractiveness was positively correlated with the ext... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882084 Sun, 16 Aug 2009 23:00:00 +0100 2882084 http://www.medworm.com/index.php?rid=2882083&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000439%2Fabstract%3Frss%3Dyes Abstract: A crucially important aspect of human cooperation is the ability to negotiate to cooperative outcomes when interests over resources conflict. Although chimpanzees and other social species may negotiate conflicting interests regarding travel direction or activity timing, very little is known about their ability to negotiate conflicting preferences over food. In the current study, we presented pairs of chimpanzees with a choice between two cooperative tasks—one with equal payoffs (e.g., 5-5) and one with unequal payoffs (higher and lower than in the equal option, e.g., 10-1). This created a conflict of interests between partners with failure to work together on the same cooperative task resulting in no payoff for either partner. The chimpanzee pairs cooperated successfully in as ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882083 Thu, 06 Aug 2009 23:00:00 +0100 2882083 http://www.medworm.com/index.php?rid=3077788&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000531%2Fabstract%3Frss%3Dyes Abstract: Neonatal features in the newborn are thought to trigger parental care, the most fundamental prosocial behaviour. The underlying mechanisms that release parental care have not yet been resolved. Here we report sex differences in the ability to discriminate cues to cuteness despite equivalence in the capability to discriminate age and facial expression. These differences become apparent in a task where adults were asked to choose the cuter of two babies. While women could reliably choose the cuter infant, men had more difficulty in doing so. When showing the exact same face pairs but asking to choose the younger or the happier baby, there was no sex difference. These results suggest that the sex difference in the ability to discriminate cues to cuteness in infants underlies female-... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=3077788 Thu, 06 Aug 2009 00:00:00 +0100 3077788 http://www.medworm.com/index.php?rid=2882088&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000543%2Fabstract%3Frss%3Dyes Abstract: It has been proposed that a common cause underlies individual differences in bodily and cognitive decline in old age. No good marker for this common cause has been identified to date. Here, fluctuating asymmetry (FA), an indicator of developmental stability that relates to intelligence differences in young adults, was measured from facial photographs of 216 surviving members of the Lothian Birth Cohort 1921 at age 83 and related to their intelligence at ages 11, 79 and 83 years. FA at age 83 was unrelated to intelligence at ages 11 and 79 and to cognitive change between 11 and 79 years. It was, however, associated with intelligence and information processing efficiency at age 83 and with cognitive change between 79 and 83 years. Significant results were limited to men, a result p... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882088 Wed, 05 Aug 2009 23:00:00 +0100 2882088 http://www.medworm.com/index.php?rid=2882087&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000403%2Fabstract%3Frss%3Dyes Abstract: Behavioural studies of the perceptual cues for female physical attractiveness have suggested two potentially important features: body fat distribution [the waist-to-hip ratio (WHR)] and overall body fat [often estimated by the body mass index (BMI)]. However, none of these studies tell us directly which regions of the stimulus images inform observers' judgments. Therefore, we recorded the eye movements of three groups of 10 male observers and three groups of 10 female observers, when they rated a set of 46 photographs of female bodies. The first sets of observers rated the images for attractiveness, the second sets rated for body fat and the third sets for WHR. If either WHR and/or body fat is used to judge attractiveness, then observers rating attractiveness should look at those... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2882087 Sun, 21 Jun 2009 23:00:00 +0100 2882087 http://www.medworm.com/index.php?rid=2686830&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000427%2Fabstract%3Frss%3Dyes Abstract: The study tested the proposition that relationship involvement influences the implicit responses of women to high- and low-status professions. It was hypothesized that when a high-involvement context was primed, women would have more positive implicit associations with high-status occupations than when a low-involvement context was primed. In contrast, when a high-involvement context was primed, women would have more negative associations with low-status occupations than when a low-involvement context was primed. To test the hypothesis, 123 female participants received a high or low relationship involvement prime. Then the participants completed a single category implicit associations test designed to measure the participants' associations with either high- or low-status occupati... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686830 Sun, 21 Jun 2009 23:00:00 +0100 2686830 http://www.medworm.com/index.php?rid=2686833&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000415%2Fabstract%3Frss%3Dyes Forensic psychology is generally defined as the application of psychology to the law. The term refers to the testimony a psychologist may give in open court, together with case-specific preparations for such testimony. Evolutionary psychologists will naturally expect Darwinian foundations to improve forensic psychology, and the book is meant to be the first step toward that end. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686833 Sun, 14 Jun 2009 23:00:00 +0100 2686833 http://www.medworm.com/index.php?rid=2686826&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000397%2Fabstract%3Frss%3Dyes Abstract: On average, men have 61% more muscle mass than women (d=3), a sex difference which is developmentally related to their much higher levels of testosterone. Potential benefits of greater male muscle mass include increased mating opportunities, while potential costs include increased dietary requirements and decreased immune function. Using data on males aged 18–59 years from the third National Health and Nutrition Examination Survey and including other relevant variables, fat-free mass (FFM) and/or limb muscle volume (LMV) are significant predictors of the numbers of total and past-year self-reported sex partners, as well as age at first intercourse. On the cost side, FFM and LMV are strong positive predictors of daily energy intake and strong negative predictors of C-reactive pr... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686826 Sun, 24 May 2009 23:00:00 +0100 2686826 http://www.medworm.com/index.php?rid=2482245&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000385%2Fabstract%3Frss%3Dyes In The Caveman Mystique (TCM), Martha McCaughey examines how evolutionary accounts of human sexuality circulate in popular culture and influence the ways that men form their ideas of how men should think and act. She goes on to critique evolutionary perspectives on human sexuality. After briefly reviewing the major claims of the book, we clarify misunderstandings of evolutionary perspectives presented and address what we see as valid criticisms of the ways that evolutionary research is sometimes generated and disseminated into popular culture. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2482245 Tue, 12 May 2009 04:00:00 +0100 2482245 http://www.medworm.com/index.php?rid=2482244&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000245%2Fabstract%3Frss%3Dyes Abstract: This paper lays out an evolutionary theory for the cognitive foundations and cultural emergence of the extravagant displays (e.g., ritual mutilation, animal sacrifice and martyrdom) that have so tantalized social scientists, as well as more mundane actions that influence cultural learning and historical processes. In Part I, I use the logic of natural selection to build a theory for how and why seemingly costly displays influence the cognitive processes associated with cultural learning — why do “actions speak louder than words?” The core idea is that cultural learners can both avoid being manipulated by their models (those they are inclined to learn from) and more accurately assess their belief commitment by attending to displays or actions by the model that would seem cos... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2482244 Tue, 12 May 2009 04:00:00 +0100 2482244 http://www.medworm.com/index.php?rid=2482243&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000208%2Fabstract%3Frss%3Dyes We examined whether this male-specific “coalitional psychology” represents in-group love or out-group hate. One hundred thirty-three college freshmen played a prisoner's dilemma game with a member of their own group and a member of another group. Both groups consisted of same-sex participants. An in-group bias (cooperation with the in-group at a level higher than cooperation with the out-group) based on expectations of cooperation from the in-group was observed for both men and women. When such expectations were experimentally eliminated, women did not show any in-group bias, whereas men still exhibited an in-group bias. This male-specific in-group bias was found to be a product of intragroup cooperation (in-group love) rather than a product of intergroup competition (out-group hate). ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2482243 Tue, 12 May 2009 04:00:00 +0100 2482243 http://www.medworm.com/index.php?rid=2686832&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000221%2Fabstract%3Frss%3Dyes Abstract: Handedness is a product of brain specialization, which in turn seems to be responsible for the higher cognitive capabilities of humans, such as language and technology. Handedness in living humans is well established and shows the highest degree of manual specialization. Studies on hand laterality in nonhuman primates, particularly in chimpanzees, remain a matter of controversy as results tend to vary depending on factors such as the tasks performed and the environment in which the individuals live. Studies in several disciplines have attempted to determine where in the course of human evolution handedness established itself, with evidence collected from sources such as paleoneurological analyses, stone tool flaking, zooarchaeological studies and dental wear analyses, the last on... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686832 Mon, 11 May 2009 23:00:00 +0100 2686832 http://www.medworm.com/index.php?rid=2686828&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000270%2Fabstract%3Frss%3Dyes Abstract: Physical attractiveness has been associated with mating behavior, but its role in reproductive success of contemporary humans has received surprisingly little attention. In the Wisconsin Longitudinal Study (1244 women, 997 men born between 1937 and 1940), we examined whether attractiveness assessed from photographs taken at age ∼18 years predicted the number of biological children at age 53–56 years. In women, attractiveness predicted higher reproductive success in a nonlinear fashion, so that attractive (second highest quartile) women had 16% and very attractive (highest quartile) women 6% more children than their less attractive counterparts. In men, there was a threshold effect so that men in the lowest attractiveness quartile had 13% fewer children than others who did not... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686828 Mon, 11 May 2009 23:00:00 +0100 2686828 http://www.medworm.com/index.php?rid=2686827&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000282%2Fabstract%3Frss%3Dyes Abstract: Studying biological and social determinants of mortality and fertility provides insight into selective pressures in a population and the possibility of trade-offs between short- and long-term reproductive success. Limited data is available from post-demographic transition populations. We studied determinants of reproductive success using multi-generational data from a large, population-based cohort of 13,666 individuals born in Sweden between 1915 and 1929. We studied the effects of birthweight for gestational age, preterm birth, birth multiplicity, birth order, mother's age, mother's marital status and family socioeconomic position (SEP) upon reproductive success, measured as total number of children and grandchildren. We further tested the hypothesis that number of grandchildre... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686827 Mon, 11 May 2009 23:00:00 +0100 2686827 http://www.medworm.com/index.php?rid=2686829&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000269%2Fabstract%3Frss%3Dyes Abstract: Previous research has demonstrated that female behaviors toward men or sexual interest are different across the menstrual cycle. However, women's receptivity to an explicit courtship solicitation still remained in question. In a field experiment, 20-year-old women were approached by 20-year-old male confederates in nightclubs and solicited to dance during the period when slow songs were played. A survey was administered to the women in order to obtain information about the number of days since the onset of previous menses. It was found that women in their fertile phase agreed more favorably to the dance request than women in their luteal phase or in their menstrual phase. (Source: Evolution and Human Behaviour) Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686829 Tue, 21 Apr 2009 23:00:00 +0100 2686829 http://www.medworm.com/index.php?rid=2686825&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000257%2Fabstract%3Frss%3Dyes This study extends previous ones showing a link between direct aggression and size and strength among young men, which were informed by the evolutionary concept of resource holding power (RHP), using measures of size, strength, flexed bicep circumference and hand grip strength among a sample of young men from the Indian state of Mizoram. The study also examined the relation of these variables to reactive and proactive aggression, to entitlement to resources (related to the threatened egotism theory of aggression) and mate value (central to a modular theory of self-esteem and more broadly to sexual selection). The findings showed only a weak association between size and strength and direct aggression, which was also significantly correlated with entitlement and mate value, as predicted. Mat... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2686825 Tue, 21 Apr 2009 23:00:00 +0100 2686825 http://www.medworm.com/index.php?rid=2494676&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000233%2Fabstract%3Frss%3Dyes Abstract: It is often assumed that parent-to-child cultural transmission leads to similarities and differences among groups evolving through descent with modification (“phylogenesis”). Similarly, cultural transmission between peers, and between adults and children who are not their offspring, is widely believed to result in groups exchanging cultural traits (“ethnogenesis”). However, neither of these assumptions has been examined empirically. Here, we test them using ethnographic data on craft learning in Iranian tribal populations and the cladistic method of phylogenetic analysis. We find that parent-to-child transmission dominates learning during childhood, but the other two forms of interindividual transmission become more important in later periods. The latter do not, however, ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2494676 Tue, 21 Apr 2009 23:00:00 +0100 2494676 http://www.medworm.com/index.php?rid=2494674&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000191%2Fabstract%3Frss%3Dyes Abstract: Why do societies collapse? We use an individual-based evolutionary model to show that, in environmental conditions dominated by low-frequency variation (“red noise”), extirpation may be an outcome of the evolution of cultural capacity. Previous analytical models predicted an equilibrium between individual learners and social learners, or a contingent strategy in which individuals learn socially or individually depending on the circumstances. However, in red noise environments, whose main signature is that variation is concentrated in relatively large, relatively rare excursions, individual learning may be selected from the population. If the social learning system comes to lack sufficient individual learning or cognitively costly adaptive biases, behavior ceases tracking envi... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2494674 Tue, 21 Apr 2009 23:00:00 +0100 2494674 http://www.medworm.com/index.php?rid=2351995&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000130%2Fabstract%3Frss%3Dyes The idea that “religion” may have evolved through Darwinian selection has seen an explosion of interest recently, giving rise to numerous journal articles, dedicated conferences and books (for reviews, see ). The field offers a treasure trove for scholars of human evolution because it spans so many topics of interest to us. First of all, there are important theoretical and empirical questions at each of Tinbergen's four levels of analysis: What is its evolutionary function? What are the proximate mechanisms? What are its developmental features? What is its phylogeny in the human lineage? It also confronts other areas of importance, including the evolution of cooperation, maladaptive behavior in modern life, levels of selection (individual vs. group selection) and multiple possible evol... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351995 Tue, 21 Apr 2009 21:43:22 +0100 2351995 http://www.medworm.com/index.php?rid=2351994&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000154%2Fabstract%3Frss%3Dyes Abstract: Previous studies sought to test for the existence of a “cheater-detection module” by testing for enhanced memory for the faces of cheaters, but past results have been inconclusive. Here, we present four experiments showing that old–new discrimination was not affected by whether a face was associated with a history of cheating, trustworthy or irrelevant behavior. In contrast, source memory for faces associated with a history of cheating (i.e., memory for the cheating context in which the face was encountered) was consistently better than source memory for other types of faces. This pattern held under a variety of conditions, including different types of judgments participants made about the stimulus persons (attractiveness in Experiment 1; likeability in Experiments 2–4), ... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351994 Tue, 21 Apr 2009 21:43:17 +0100 2351994 http://www.medworm.com/index.php?rid=2351993&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000142%2Fabstract%3Frss%3Dyes This study examines the effects of ingroup favoritism and outgroup hostility (“parochialism”), as well as of conditionally cooperative strategies, in explaining contributions to experimental public goods games. The experimental conditions vary group composition along two culturally inheritable traits (political party preference and religious affiliation) and one trivial, “minimal” trait (birth season). We contrast ingroup, outgroup, and random group conditions and investigate the relation between the own contribution to the public good and the expectations about other group members' behavior in each one of them. We find evidence for ingroup favoritism but no support for a separate tendency towards outgroup hostility. Further, conditional cooperation and ingroup bias are, to some ex... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351993 Tue, 21 Apr 2009 21:43:16 +0100 2351993 http://www.medworm.com/index.php?rid=2351992&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000026%2Fabstract%3Frss%3Dyes Abstract: Prosociality is a fundamental theme in all branches of the human behavioral sciences. Evolutionary theory sets an even broader stage by examining prosociality in all species, including the distinctive human capacity to cooperate in large groups of unrelated individuals. We use evolutionary theory to investigate human prosociality at the scale of a small city (Binghamton, NY), based on survey data and a direct measure of prosocial behavior. In a survey of public school students (Grades 6–12), individual prosociality correlates strongly with social support, which is a basic requirement for prosociality to succeed as a behavioral strategy in Darwinian terms. The most prosocial individuals receive social support from multiple sources (e.g., family, school, neighborhood, religion an... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351992 Tue, 21 Apr 2009 21:43:14 +0100 2351992 http://www.medworm.com/index.php?rid=2351991&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513809000038%2Fabstract%3Frss%3Dyes Abstract: Stepchildren are abused, neglected and murdered at higher rates than those who live with two genetically related parents. Daly and Wilson used kin selection theory to explain this finding and labeled the phenomenon “discriminative parental solicitude.” I examined discriminative parental solicitude in American households composed of both genetic and unrelated adopted children. In these families, kin selection predicts parents should favor their genetic children over adoptees. Rather than looking at cases of abuse, neglect, homicide and other antisocial behavior, I focused on the positive investments parents made in their children as well as the outcomes of each child. The results show that parents invested more in adopted children than in genetically related ones, especially i... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351991 Tue, 21 Apr 2009 21:43:06 +0100 2351991 http://www.medworm.com/index.php?rid=2351990&cid=s_38471_36_f&fid=38471&url=http%3A%2F%2Fwww.ehbonline.org%2Farticle%2FPIIS1090513808001220%2Fabstract%3Frss%3Dyes Abstract: Evolutionary and economic models of the family propose that parents face a fundamental trade-off between fertility and investment per offspring. However, tests of this hypothesis have focused primarily on offspring outcomes rather than direct measures of parental investment. Existing studies of parenting also suffer a number of methodological problems now recognized as common sources of error in sociodemographic studies. Here, we present a more definitive picture of the effects of family structure on parental care by analyzing an extensive longitudinal dataset of contemporary British families (the Avon Longitudinal Study of Parents and Children). Unlike other studies, we simultaneously track maternal and paternal behaviors within the same family and consider variation both across... Evolution and Human Behaviour journals http://www.medworm.com/rss/comments.php?id=2351990 Tue, 21 Apr 2009 21:42:49 +0100 2351990