Yay Dr. Zany! And a good post in general.

However, Western behavior in the Ultimatum Game seems to be a cultural, not biological, phenomenon.

By the mid‐1990s researchers were arguing that a set of robust experimental findings from behavioral economics were evidence for set of evolved universal motivations (Fehr & Gächter 1998, Hoffman et al. 1998). Foremost among these experiments, the Ultimatum Game, provides a pair of anonymous subjects with a sum of real money for a one‐shot interaction. One of the pair—the proposer—can offer a portion of this sum to a second subject, the responder. Responders must decide whether to accept or reject the offer. If a responder accepts, she gets the amount of the offer and the proposer takes the remainder; if she rejects both players get zero. If subjects are motivated purely by self‐interest, responders should always accept any positive offer; knowing this, a self‐interested proposer should offer the smallest non‐zero amount. Among subjects from industrialized populations—mostly undergraduates from the U.S., Europe, and Asia—proposers typically offer an amount between 40% and 50% of the total, with a modal offer of usually 50% (Camerer 2003). Offers below about 30% are often rejected.

With this seemingly robust empirical finding in their sights, Nowak, Page and Sigmund (2000) constructed an evolutionary analysis of the Ultimatum Game. When they modeled the Ultimatum Game exactly as played, they did not get results matching the undergraduate findings. However, if they added reputational information, such that players could know what their partners did with others on previous rounds of play, the analysis predicted offers and rejections in the range of typical undergraduate responses. They concluded that the Ultimatum Game reveals humans’ species‐specific evolved capacity for fair and punishing behavior in situations with substantial reputation influence. But, since the Ultimatum Game is typically done one‐shot without reputational information, they argued that people make fair offers and reject unfair offers because their motivations evolved in a world where such interactions were not fitness relevant—thus, we are not evolved to fully incorporate the possibility of non‐reputational action in our decision‐making, at least in such artificial experimental contexts.

Recent comparative work has dramatically altered this initial picture. Two unified projects (which we call Phase 1 and Phase 2) have deployed the Ultimatum Game and other related experimental tools across thousands of subjects randomly sampled from 23 small‐scale human societies, including foragers, horticulturalists, pastoralists, and subsistence farmers, drawn from Africa, Amazonia, Oceania, Siberia and New Guinea (Henrich et al. 2005, Henrich et al. 2006). Three different experimental measures show that the people in industrialized societies consistently occupy the extreme end of the human distribution. Notably, small‐scale societies with only face‐to‐face interaction behaved in a manner reminiscent of Nowak et. al.’s analysis before they added the reputational information. That is, these populations made low offers and did not reject. [...]

Analyses of these data show that a population’s degree of market integration and its participation in a world religion both independently predict higher offers, and account for much of the variation between populations. Community size positively predicts greater punishment (Henrich et al. n.d.). The authors suggest that norms and institutions for exchange in ephemeral interactions culturally coevolved with markets and expanding larger‐scale sedentary populations. In some cases, at least in their most efficient forms, neither markets nor large population were feasible before such norms and institutions emerged. That is, it may be that what behavioral economists have been measuring in such games is a specific set of social norms, evolved for dealing with money and strangers, that have emerged since the origins of agriculture and the rise of complex societies.