Pathogen Prevalence, Group Bias, and Collectivism in the Standard Cross-Cultural Sample

It has been argued that people in areas with high pathogen loads will be more likely to avoid outsiders, to be biased in favor of in-groups, and to hold collectivist and conformist values. Cross-national studies have supported these predictions. In this paper we provide new pathogen codes for the 186 cultures of the Standard Cross-Cultural Sample and use them, together with existing pathogen and ethnographic data, to try to replicate these cross-national findings. In support of the theory, we found that cultures in high pathogen areas were more likely to socialize children toward collectivist values (obedience rather than self-reliance). There was some evidence that pathogens were associated with reduced adult dispersal. However, we found no evidence of an association between pathogens and our measures of group bias (in-group loyalty and xenophobia) or intergroup contact.     

Why Go There? Evolution of Mobility and Spatial Cognition in Women and Men

Males in many non-monogamous species have larger ranges than females do, a sex difference that has been well documented for decades and seems to be an aspect of male mating competition. Until recently, parallel data for humans have been mostly anecdotal and qualitative, but this is now changing as human behavioral ecologists turn their attention to matters of individual mobility. Sex differences in spatial cognition were among the first accepted psychological sex differences and, like differences in ranging behavior, are documented for a growing set of species. This special issue is dedicated to exploring the possible adaptive links between these cognitive and ranging traits. Multiple hypotheses, at various levels of analysis, are considered. At the functional (ultimate) level, a mating-competition hypothesis suggests that range expansion may augment mating opportunities, and a fertility-and-parental-care hypothesis suggests that range contraction may facilitate offspring provisioning. At a more mechanistic (proximate) level, differences in cue availability may support or inhibit particular sex-specific navigation strategies, and spatial anxiety may usefully inhibit travel that would not justify its costs. Studies in four different cultures—Twe, Tsimane, Yucatec Maya, and Faroese—as well as an experimental study using virtual reality tools are the venue for testing these hypotheses. Our hope is to stimulate more research on the evolutionary and developmental processes responsible for this suite of linked behavioral and cognitive traits.     

Mobility and Navigation among the Yucatec Maya

Sex differences in range size and navigation are widely reported, with males traveling farther than females, being less spatially anxious, and in many studies navigating more effectively. One explanation holds that these differences are the result of sexual selection, with larger ranges conferring mating benefits on males, while another explanation focuses on greater parenting costs that large ranges impose on reproductive-aged females. We evaluated these arguments with data from a community of highly monogamous Maya farmers. Maya men and women do not differ in distance traveled over the region during the mate-seeking years, suggesting that mating competition does not affect range size in this monogamous population. However, men’s regional and daily travel increases after marriage, apparently in pursuit of resources that benefit families, whereas women reduce their daily travel after marriage. This suggests that parental effort is more important than mating effort in this population. Despite the relatively modest overall sex difference in mobility, Maya men were less spatially anxious than women, thought themselves to be better navigators, and pointed more accurately to distant locations. A structural equation model showed that the sex by marital status interaction had a direct effect on mobility, with a weaker indirect effect of sex on mobility mediated by navigational ability.     

Sex differences in spatial cognition among Hadza foragers

This paper describes sex differences in spatial competencies among the Hadza, a mobile hunter–gatherer population in Tanzania. It addresses the following questions: (a) Is the usual male advantage in Euclidean spatial abilities found in this population, where both women and men are highly mobile? (b) Do Hadza women have better object location memory than men, as the gathering hypothesis predicts? (c) Do women who are nominated by others as being good at finding bushfoods excel at the object location memory task? We tested object location memory with a version of the memory game using cards of local plants and animals. This allowed us to also ask whether women and men would have better spatial memory for the plant and animal cards, respectively. We found that Hadza men were significantly better than women in three tests of spatial ability: the water-level test, targeting, and the ability to point accurately to distant locations (the latter only in the less mobile groups). There was a trend toward a male advantage at the object location memory task, in contrast to results found previously in nonforaging populations, and women's performance at the task deteriorated with age, while that of men did not. The women who were nominated by peers as being good at finding bushfoods were consistently older women. We discuss the probable hormonal causes and functional consequences of age changes in the spatial competencies of female foragers.     

G//ana territorial organization

This analysis of G//ana territorial organization shows how land rights are acquired and how they affect patterns of land use. Both spatial and social boundaries are discussed. It is shown that the appearance of overlapping spatial boundaries is clarified through a focus on the land rights of individuals and a consideration of historical population movements over the region. The discussion of social boundaries shows that, while interterritorial marriage and mobility networks are extensive, increases in property and food production appear to be associated with a closing of social boundaries (increased social nucleation). This is suggested by greater endogamy and a trend toward patrilineal inheritance of land rights in recent years.     

Women's mating strategies

What does a woman want? The traditional evolutionist's answer to Freud's famous query is that a woman's extensive investment in each of her children implies that she can maximize her fitness by restricting her sexual activity to one, or at most, a few high-quality males. Because acquiring resources for her offspring is of paramount importance, a woman will try to attract wealthy, high-status men who are willing and able to help her. She must be coy and choosy, limiting her attentions to men who are worthy of her and emphasizing her chastity so as not to threaten the paternity confidence of her mate. The lady has been getting more complicated of late, however. As Sarah Hrdy¹ predicted, we now have evidence that women, like other female primates, are also competitive, randy creatures. Women have been seen competing with their rivals using both physical aggression^2,3 and more subtle derogation of competitors.⁴ While they are still sometimes coy and chaste, women have also been described recently as sexy and sometimes promiscuous creatures, manipulating fatherhood by the timing of orgasm^5,6 and using their sexuality to garner resources from men. The real answer to Freud's query, of course, is that a woman wants it all; a man with the resources and inclination to invest, and with genes that make him attractive to other women so that her sons will inherit his success. Her strategies for attaining these somewhat conflicting aims, and her success in doing so, are shaped by her own resources and options and by conflicts of interest with men and other women.