Cross-cultural invariances in the architecture of shame.

Human foragers are obligately group-living, and their high dependence on mutual aid is believed to have characterized our species' social evolution. It was therefore a central adaptive problem for our ancestors to avoid damaging the willingness of other group members to render them assistance. Cognitively, this requires a predictive map of the degree to which others would devalue the individual based on each of various possible acts. With such a map, an individual can avoid socially costly behaviors by anticipating how much audience devaluation a potential action (e.g., stealing) would cause and weigh this against the action's direct payoff (e.g., acquiring). The shame system manifests all of the functional properties required to solve this adaptive problem, with the aversive intensity of shame encoding the social cost. Previous data from three Western(ized) societies indicated that the shame evoked when the individual anticipates committing various acts closely tracks the magnitude of devaluation expressed by audiences in response to those acts. Here we report data supporting the broader claim that shame is a basic part of human biology. We conducted an experiment among 899 participants in 15 small-scale communities scattered around the world. Despite widely varying languages, cultures, and subsistence modes, shame in each community closely tracked the devaluation of local audiences (mean r = +0.84). The fact that the same pattern is encountered in such mutually remote communities suggests that shame's match to audience devaluation is a design feature crafted by selection and not a product of cultural contact or convergent cultural evolution.

Arranged and non-arranged marriages have similar reproductive outcomes in Nepal.

Much of the evolutionary literature on mate choice presumes that individual mate preferences function to increase individual fitness, and this assumption has been confirmed in several experimental studies with animals. However, human mate choice, in many cultures, is heavily controlled by parents via arranged marriages, rather than the selection of the marrying individuals. Several studies have demonstrated that parents and offspring do not exhibit identical preferences for an in-law or spouse, respectively. If parental choice thwarts offspring's evolved mate preferences from being expressed, then arranged marriages should reduce fitness. Using data from the Chitwan Valley Family Study, I examined whether having an arranged marriage, as compared to a non-arranged marriage, is associated with differences in total births, offspring survival to age 15, or interbirth intervals in Nepal, a culture with a rich history of arranged marriage. I find that there are no differences in any reproductive outcomes between arranged, co-selected, and self-selected marriages. These results indicate that individuals in arranged and non-arranged marriages may achieve similar fitness outcomes via different pathways, which may be unique to human mating systems.

Socioeconomic benefits and limited parent-offspring disagreement in arranged marriages in Nepal.

Mate preferences probably evolved to increase fitness; however, studies using arranged and non-arranged marriage as proxies for limited and free mate choice (respectively) do not find any reproductive differences. We explore why arranged and non-arranged marriages are an imperfect proxy for limited and free-choice matings and what fitness effects different marriage types could produce. Data from focus group discussions with men and women in Nepal show that there are three spouse choice categories with differing levels of parental influence over mate choice, reinforcing that arranged and non-arranged are not dichotomous. Discussions also show that parents and offspring, especially sons, may be more aligned in in-law/mate preferences than expected, demonstrating the need to establish clear domains of parent-offspring disagreement over spouse choice in the community before investigating fitness. Several social and financial benefits that are only available to arranged couples in this community were detected, and these benefits could compensate for any costs of not choosing a spouse independently. These benefits of arranged marriage are more salient for women than for men. These discussions indicate that predictions about the effects of spouse choice on fitness outcomes may differ for men and women and depend on community-specific socioeconomic benefits.