Spontaneous Altruism by Chimpanzees and Young Children

TLDR

Altruistic acts that cost the actor and lack immediate reward are common in humans, yet are thought to be unique to our species, with prior chimpanzee studies largely negative. In two comparative experiments, semi‑free ranging chimpanzees helped unfamiliar humans to the same extent as human infants regardless of reward or cost, and in a third experiment they helped an unrelated conspecific obtain food by applying a newly learned skill. These findings show that chimpanzees exhibit spontaneous, cost‑bearing helping comparable to human infants, implying that the evolutionary roots of human altruism extend further back than previously believed.

Abstract

People often act on behalf of others. They do so without immediate personal gain, at cost to themselves, and even toward unfamiliar individuals. Many researchers have claimed that such altruism emanates from a species-unique psychology not found in humans' closest living evolutionary relatives, such as the chimpanzee. In favor of this view, the few experimental studies on altruism in chimpanzees have produced mostly negative results. In contrast, we report experimental evidence that chimpanzees perform basic forms of helping in the absence of rewards spontaneously and repeatedly toward humans and conspecifics. In two comparative studies, semi–free ranging chimpanzees helped an unfamiliar human to the same degree as did human infants, irrespective of being rewarded (experiment 1) or whether the helping was costly (experiment 2). In a third study, chimpanzees helped an unrelated conspecific gain access to food in a novel situation that required subjects to use a newly acquired skill on behalf of another individual. These results indicate that chimpanzees share crucial aspects of altruism with humans, suggesting that the roots of human altruism may go deeper than previous experimental evidence suggested.