Play in the Peter Pan ape

Baco, the alpha male of a foreign community on the east side of the local river, is sitting side by side with Jiro, a young adult male from the west side. They are watching each other closely while chewing on fruit. Seemingly out of the blue and with no hesitation, Jiro reaches up over his head, grabs a branch, and swings his whole body into Baco’s with great force and kicks him in his midsection repeatedly. Baco, who is larger and stronger, sits back and takes the kicking for a few seconds. Then, having had enough of this ‘teenage’ behaviour, he leans forward, grabs Jiro’s upper body, and overpowers him while biting his shoulder. Now the tables are turned — but only until Baco’s grip lessens and Jiro escapes. Yet it doesn’t end there. After having finally freed himself, Jiro returns for more. What is going on? The next stage reveals the answer. Baco spreads his legs, displaying his genitalia to Jiro, who crouches down, extends his arm and starts poking the older male’s testicles. Baco starts rocking his body, giving rhythm to this unique exchange. Then Baco starts hitting Jiro with open hands, and I see the alpha male is displaying the unmistakable, relaxed, open-mouthed play face. This is not a fight, this is play: play between two adult bonobo males in their natural habitat, south of the river Congo. In this Primer, Isabel Behncke provides an overview of the biology of fun in bonobos, with a special focus on adult play and how it relates to social bonding and the flexibility component of intelligence.