Human Nature-An Interdisciplinary Biosocial Perspective最新文献

There is a popular idea that archaic humans commonly used wooden clubs as their weapons. This is not based on archaeological finds, which are minimal from the Pleistocene, but rather on a few ethnographic analogies and the association of these weapons with simple technology. This article presents the first quantitative cross-cultural analysis of the use of wooden clubs and throwing sticks for hunting and violence among foragers. Using a sample of 57 recent hunting-gathering societies from the Standard Cross-Cultural Sample, it is shown that the majority used clubs for violence (86%) and/or hunting (74%). Whereas in hunting and fishing the club usually served only as a secondary tool, 33% of societies used the club as one of their main fighting weapons. The use of throwing sticks was less frequent among the societies surveyed (12% for violence, 14% for hunting). Based on these results and other evidence, it is argued that the use of clubs by early humans was highly probable, at least in the simplest form of a crude stick. The great variation in the forms and use of clubs and throwing sticks among recent hunter-gatherers, however, indicates that they are not standardized weapons and that similar variation may have existed in the past. Many such prehistoric weapons may therefore have been quite sophisticated, multifunctional, and carried strong symbolic meaning.

Folk stories featuring prosocial content are ubiquitous across cultures. One explanation for the ubiquity of such stories is that stories teach people about the local socioecology, including norms of prosociality, and stories featuring prosocial content may increase generosity in listeners. We tested this hypothesis in a sample of 185 Hadza hunter-gatherers. We read participants a story in which the main character either swims with another person (control story) or rescues him from drowning (prosocial story). After hearing the story, participants played a dictator game with dried meat sticks and then were given a recall test of facts presented in the story. There was moderate evidence for a small effect of the prosocial story: participants who heard the prosocial story gave an estimated 0.22 [90% HDI: -0.12-0.57] more meat sticks than those who heard the control story. However, the association between generosity and sex, marital status, and region of residence was stronger; men gave more than women, unmarried participants gave more than married participants, and participants living in a region with more exposure to markets gave more than participants living further from markets. There was no evidence that the prosocial story was more easily recalled than the control story. These results provide some support for the hypothesis that prosocial stories can increase prosociality in listeners, though the effect of hearing a single story is small.

Humans have a complex and dynamic mating system, and there is evidence that our modern sexual preferences stem from evolutionary pressures. In the current paper we explore male use of a dual mating strategy: simultaneously pursuing both a long-term relationship (pair-bonding) as well as short-term, extra-pair copulations (variety-seeking). The primary constraint on such sexual pursuits is partner preferences, which can limit male behavior and hence cloud inferences about male preferences. The aim of this study was to investigate heterosexual male mating preferences when largely unconstrained by female partner preferences. In service of this goal, female full-service sex workers (N = 6) were surveyed on the traits and behaviors of their male clients (N = 516) and iterative cluster analysis was used to identify male mating typologies. Two clusters emerged: clients seeking a pair-bonding experience and clients seeking a variety experience. Results also suggested that romantically committed men were more likely to seek a variety experience than a relationship experience. We conclude that men desire both pair-bonding and sexual variety, and that their preference for one might be predicted by fulfilment of the other. These findings have implications for relationships, providing insight into motivations for male infidelity.

Recent studies in social endocrinology have explored the effects of social relationships on female reproductive steroid hormones-estradiol and progesterone-investigating whether they are suppressed in partnered and parous women. Results have been mixed for these hormones although evidence is more consistent that partnered women and women with young children have lower levels of testosterone. These studies were sequential to earlier research on men, based on Wingfield's Challenge Hypothesis, which showed that men in committed relationships, or with young children, have lower levels of testosterone than unpartnered men or men with older or no children. The study described here explored associations between estradiol and progesterone with partnership and parity among women from two different ethnicities: South Asian and white British. We hypothesized that both steroid hormones would be lower among partnered and/or parous women with children ≤3 years old, regardless of ethnicity. In this study we analyzed data from 320 Bangladeshi and British women of European origin aged 18 to 50 who participated in two previous studies of reproductive ecology and health. Levels of estradiol and progesterone were assayed using saliva and/or serum samples and the body mass index calculated from anthropometric data. Questionnaires provided other covariates. Multiple linear regressions were used to analyze the data. The hypotheses were not supported. We argue here that, unlike links between testosterone and male social relationships, theoretical foundations for such relationships with female reproductive steroid hormones are lacking, especially given the primary role of these steroids in regulating female reproductive function. Further longitudinal studies are needed to explore the bases of independent relationships between social factors and female reproductive steroid hormones.

Figurative drawing is a skill that takes time to learn, and it evolves during different childhood phases that begin with scribbling and end with representational drawing. Between these phases, it is difficult to assess when and how children demonstrate intentions and representativeness in their drawings. The marks produced are increasingly goal-oriented and efficient as the child's skills progress from scribbles to figurative drawings. Pre-figurative activities provide an opportunity to focus on drawing processes. We applied fourteen metrics to two different datasets (N = 65 and N = 344) to better understand the intentional and representational processes behind drawing, and combined these metrics using principal component analysis (PCA) in different biologically significant dimensions. Three dimensions were identified: efficiency based on spatial metrics, diversity with color metrics, and temporal sequentiality. The metrics at play in each dimension are similar for both datasets, and PCA explains 77% of the variance in both datasets. Gender had no effect, but age influenced all three dimensions differently. These analyses for instance differentiate scribbles by children from those drawn by adults. The three dimensions highlighted by this study provide a better understanding of the emergence of intentions and representativeness in drawings. We discussed the perspectives of such findings in comparative psychology and evolutionary anthropology.

I present a detailed ethnographic study of magic and divination of the Nuosu people in southwest China and offer a cognitive account of the surprising prevalence of these objectively ineffective practices in a society that has ample access to modern technology and mainstream Han culture. I argue that in the belief system of the Nuosu, ghosts, divination, and magical healing rituals form a closely interconnected web that gives sense and meaning to otherwise puzzling practices, and such a belief system is importantly supported and reinforced by individual's everyday experiences. Contemporary Nuosu people overwhelmingly treat these practices as instruments for achieving specific ends and often entertain considerable uncertainty regarding their efficacy, which may be overestimated for a number of reasons, including the following: (1) the intuitive plausibility of divination for ghost identification and exorcist rituals is enhanced by the belief in the existence of ghosts as a result of abductive reasoning, (2) negative instances (divinatory or healing ritual failures) are underreported, and (3) people's misperception of the probability of uncertain events' occurrence often prevents them from realizing that the efficacies of magical/divinatory practices do not outperform chance. I conclude with some comments on the generalizability of the psychological and social mechanisms discussed.

Most research on transmission biases in cultural evolution has treated different biases as distinct strategies. Here I present a model that combines both frequency dependent bias (including conformist bias) and payoff bias in a single decision-making calculus and show that such an integrated learning strategy may be superior to relying on either bias alone. Natural selection may operate on humans' relative dependence on frequency and payoff information, but both are likely to contribute to the spread of variants with high payoffs. Importantly, the magnitude of conformist bias affects the evolutionary dynamics, and I show that an intermediate level of conformity may be most adaptive and may spontaneously evolve as it resists the invasion of low-payoff variants yet enables the fixation of high-payoff variants in the population.

Many cognitive and evolutionary theories of religion argue that supernatural explanations are byproducts of our cognitive adaptations. An influential argument states that our supernatural explanations result from a tendency to generate anthropomorphic explanations, and that this tendency is a byproduct of an error management strategy because agents tend to be associated with especially high fitness costs. We propose instead that anthropomorphic and other supernatural explanations result as features of a broader toolkit of well-designed cognitive adaptations, which are designed for explaining the abstract and causal structure of complex, unobservable, and uncertain phenomena that have substantial impacts on fitness. Specifically, we argue that (1) mental representations about the abstract vs. the supernatural are largely overlapping, if not identical, and (2) when the data-generating processes for scarce and ambiguous observations are complex and opaque, a naive observer can improve a bias-variance trade-off by starting with a simple, underspecified explanation that Western observers readily interpret as "supernatural." We then argue that (3) in many cases, knowledge specialists across cultures offer pragmatic services that involve apparently supernatural explanations, and their clients are frequently willing to pay them in a market for useful and effective services. We propose that at least some ethnographic descriptions of religion might actually reflect ordinary and adaptive responses to novel problems such as illnesses and natural disasters, where knowledge specialists possess and apply the best available explanations about phenomena that would otherwise be completely mysterious and unpredictable.

We tested the good genes ovulatory shift hypothesis through speed-dating, an ecologically valid paradigm with real life consequences. Fifteen speed-dating sessions of 262 single Asian Americans were held. We analyzed 850 speed-dates involving 132 men and 100 normally ovulating women, finding ovulatory shifts in the desirability of men with more masculine facial measurements (smaller eye-mouth-eye angle, larger lower face to full face height ratio, and smaller facial width to lower face height ratio) in the predicted direction. However, there was no support for ovulatory shifts in preferences for men's self-reported height. In addition, the expected shifts were not found for women's second date offers to men. Therefore, with natural stimuli and in a competitive dating scenario, we partially replicated previously documented ovulatory shifts in women's preferences for men.

Weight- (WAZ), height- (HAZ), and BMI-for-age (BMIZ) are frequently used to assess malnutrition among children. These measures represent different categories of risk and are usually hypothesized to be affected by distinct factors, despite their inherent relatedness. Life history theory suggests weight should be sacrificed before height, indicating a demonstrable relationship among them. Here we evaluate impact of family composition and household economics on these measures of nutritional status and explore the role of WAZ as a factor in HAZ. Anthropometrics, family demographics, and measures of household economy were collected from Sidama agropastoralist children in a peri-urban village in southwestern Ethiopia (n = 157; 79 girls). Just over half of the sample (50.9%) had z-scores of - 2SD or below on at least one measure, indicating an elevated risk of morbidity/mortality; 30% were at or below - 2SD on two or more measures. We used hierarchical linear regression with random intercept analysis to model WAZ and HAZ. Siblings and crop sales significantly decrease WAZ while electricity, agriculture, and polygyny improve z-scores; however, an interaction between polygyny and siblings indicates negative effects of siblings in polygynous families and positive effects in nonpolygynous ones (adj. R² = 66.5%). For HAZ, agriculture and electricity are positively associated with z-scores whereas siblings have a negative effect; the interaction term again indicates that effects of siblings vary in polygynous and nonpolygynous families (adj. R² = 74.2%). A mediation model exploring the role of weight in height outcomes suggests not only that WAZ has direct effects on HAZ but also that effects of electricity and agriculture on HAZ are partially mediated by WAZ. Our findings indicate that WAZ and HAZ are primarily affected by shared variables, but effects of siblings vary by polygyny status. Long-term outcomes (HAZ) among Sidama children would likely benefit from interventions focused on stabilizing WAZ across family members.