Chimps play like humans: Playful behavior of young chimps develops like that of children

Playful behavior is widespread in mammals, and has important developmental consequences. A recent study of young chimpanzees shows that these animals play and develop much the same way as human children. The work, to be published in the Nov. 16 issue of the online journal PLoS ONE, can therefore also shed light on the role of human play behavior.

The authors of the study, Elisabetta Palagi and Giada Cordoni, of the University of Pisa in Italy, found that chimpanzee solitary play peaks in infancy, while the time spent in social play was relatively constant between infants and juveniles. However, the type of social play changed quite a bit as the animals grew up, in terms of measures like complexity and playmate choice. In comparing these behaviors to previous work conducted with humans, they found that both species show significant quantitative and qualitative development in play behavior from infancy to juvenility. Moreover, both chimps and humans consistently use playful facial expressions to communicate and build social networks.

They also analyzed playmate choice and found that both humans and chimps prefer peers for play partners. Dr. Palagi explains that this is the first research comparing the ontogeny of play behavior in chimpanzees with that of humans, in a standardized way. It is important, because this kind of human data often comes from psychological research, not from ethological research.