Ethnocentrism and xenophobia: a cross-cultural study

Journal ArticleAnalyzes the factors influencing ethnic affiliation and interethnic hostility. Relationship between intraethnic loyalty and risk of famine; Continuity of violence at different levels of groupings; Analysis of local and intercommunity conflict

Sex differences in aggression: what does evolutionary theory predict?

Journal ArticleThe target article claims that evolutionary theory predicts the emergence of sex differences in aggression in early childhood, and that there will be no sex difference in anger. It also finds an absence of sex differences in spousal abuse in Western societies. All three are puzzling from an evolutionary perspective and warrant further discussion

Waist-to-hip ratio across cultures: trade-offs between androgen- and estrogen-dependent traits

Journal ArticleA gynoid pattern of fat distribution, with small waist and large hips (low waist-to-hip ratio, or WHR) holds significant fitness benefits for women: women with a low WHR of about 0.7 are more fecund, are less prone to chronic disease, and (in most cultures) are considered more attractive. Why, then, do nearly all women have a WHR higher than this putative optimum? Is the marked variation in this trait adaptive? This paper first documents the conundrum by showing that female WHR, especially in non-Western populations, is higher than the putative optimum even among samples that are young, lean, and dependent on traditional diets. The paper then proposes compensating benefits to a high WHR that can explain both its prevalence and variation in the trait. The evidence indicates that the hormonal profile associated with highWHR (high androgen and cortisol levels, low estrogens) favors success in resource competition, particularly under stressful and difficult circumstances, even though this carries fitness costs in fecundity and health. Adrenal androgens, in particular,may play an important role in enabling women to respond to stressful challenges

How women compete

ReviewMen are more physically aggressive and more risk-prone than women, but are not necessarily more competitive. New data show the gender difference in competitiveness to be one of kind rather than degree, with women and men competing in different ways and, to some extent, over different objectives, but not differing in overall strength of competitive feeling

Territoriality among human foragers: ecological models and an application to four Bushman Groups

Journal ArticleDiscussions of human territoriality have become more sophisticated in recent years; we see fewer arguments for or against the adaptiveness of territoriality for mankind in general and more attempts to probe the ecological factors that make territoriality adaptive in particular circumstances

Competition between foragers and food producers on the Botletli River, Botswana

Journal ArticleThe immigration of food-producing groups into areas occupied by hunters and gatherers must have been a common occurrence in prehistory. How were the hunter-gatherers affected by this? I describe here two groups of Kalahari Basarwa ('Bushmen'), one living along the flood plain of the lower Botletli river, the other occupying the savanna a short distance away from the river. These two groups differed in subsistence and social organisation and were affected by immigrant herders and farmers in strikingly different ways. Today the Basarwa of the flood plain are wealthy cattle owners, whereas those of the savanna are poor and have few or no cattle. How and why did the two groups respond so differently to the same competitive threat

Why is testosterone associated with divorce in men?

ReviewThere is evidence that in women high levels of testosterone are associated with more sexual partners and more permissive sexual attitudes. If a similar relationship holds true for men, the higher basal testosterone levels of divorced and unmarried men may be caused by this relationship rather than by testosterone's effect on dominance striving

On territoriality in hunter-gatherers

Journal ArticleCashdan's intention of using an evolutionary framework to examine cross-cultural variations in territorial defense is admirable, but her argument about the applicability of available models, her own model, and the data used to support it (CA 24:47-66) are all severely flawed. Specifically, Cashdan makes three errors. First, she erroneously assumes that only humans (and only some human groups) limit access to social groups. Second, she erroneously equates access to social group membership with access to the resources that the social group believes it has rights over. Third, she treats subjective impressions and interpretations as if they were data accurately gathered to address the topic of concern

Harm avoidance and mobility during middle childhood and adolescence among Hadza foragers

Cross-cultural sex differences in mobility and harm avoidance have been widely reported, often emphasizing fitness benefits of long-distance travel for males and high costs for females. Data emerging from adults in small-scale societies, however, are challenging the assumption that female mobility is restricted during reproduction. Such findings warrant further exploration of the ontogeny of mobility. Here, using a combination of machine-learning, mixed-effects linear regression, and GIS mapping, we analyze range size, daily distance traveled, and harm avoidance among Hadza foragers during middle childhood and adolescence. Distance traveled increased with age and, while male adolescents had the longest daily ranges, average daily distance traveled by each sex was similar. We found few age- or sex-related patterns in harm-avoidant responses and a high degree of individual variation. When queried on the same issues, children and their parents were often in alignment as to expectations pertaining to harm avoidance, and siblings tended to behave in similar ways. To the extent that sex differences in mobility did emerge, they were associated with ecological differences in physical threats associated with sex-specific foraging behaviors. Further, we found no strong association between harm avoidance and mobility. Young Hadza foragers of both sexes are highly mobile, regardless of how harm avoidant they are. Taken together, our findings indicate that the causal arrows between harm avoidance and mobility must be evaluated in ecologically specific frameworks where cultural expectations of juvenile mobility can be contextualized

Gendered movement ecology and landscape use in Hadza hunter-gatherers

Understanding how gendered economic roles structure space use is critical to evolutionary models of foraging behaviour, social organization and cognition. Here, we examine hunter-gatherer spatial behaviour on a very large scale, using GPS devices worn by Hadza foragers to record 2,078 person-days of movement. Theory in movement ecology suggests that the density and mobility of targeted foods should predict spatial behaviour and that strong gender differences should arise in a hunter-gatherer context. As predicted, we find that men walked further per day, explored more land, followed more sinuous paths and were more likely to be alone. These data are consistent with the ecology of male- and female-targeted foods and suggest that male landscape use is more navigationally challenging in this hunter-gatherer context. Comparisons of Hadza space use with space use data available for non-human primates suggest that the sexual division of labour likely co-evolved with increased sex differences in spatial behaviour and landscape use