Food-sharing behaviour within a group of douc monkeys (Pygathrix nemaeus nemaeus)

Hunger Games

Social-welfare policies are a modern instantiation of a phenomenon that has pervaded human evolutionary history: resource sharing. Ancestrally, food was a key shared resource in situations of temporary hunger. If evolved human psychology continues to shape how individuals think about current, evolutionarily novel conditions, this invites the prediction that attitudes regarding welfare politics are influenced by short-term fluctuations in hunger. Using blood glucose levels as a physiological indicator of hunger, we tested this prediction in a study in which participants were randomly assigned to conditions in which they consumed soft drinks containing either carbohydrates or an artificial sweetener. Analyses showed that participants with experimentally induced low blood glucose levels expressed stronger support for social welfare. Using an incentivized measure of actual sharing behavior (the dictator game), we further demonstrated that this increased support for social welfare does not translate into genuinely increased sharing motivations. Rather, we suggest that it is “cheap talk” aimed at increasing the sharing efforts of other individuals.

Acquisition by a pigtail macaque of behavior patterns beyond the natural repertoire of the species

A female Macaca nemestrina was toilet trained at the age of 8 months and has learned to control urination at will. Giving is used by the monkey as a means of social manipulation but never in an altruistic context. An analysis of the constraints on learning to control elimination and to give in nonhuman primates shows that only certain components of these behaviors are contraprepared. A hypothesis for the origin of giving in Hominids is proposed, and attention is drawn to the opportunity for studying voluntary behavior in monkeys.