While adults engage in less play than children, social play throughout adulthood is considered a universal aspect of human behavior. It plays a vital role in fostering tolerance, unity, bonding, and collaboration. In contrast, adult play among other animal species is viewed as uncommon. However, a recent study published in the Cell Press journal Current Biology on November 21 reveals that some chimpanzees, similar to humans, continue to engage in play throughout their lives, particularly before collaborating on tasks that require teamwork.
“Our research demonstrates that social play among adult chimpanzees contributes to various cooperative behaviors, ranging from pair interactions to complex activities that necessitate the coordination of several individuals,” states Liran Samuni from the German Primate Center in Göttingen, Germany, and the Taï Chimpanzee Project in Côte d’Ivoire. “We have discovered a significant connection between this joyful social interaction and the more sophisticated forms of collaboration observed in non-human species.”
Samuni and her team have focused on three closely-knit groups of chimpanzees residing in the Taï Forest of Côte d’Ivoire. Previous studies on adult play in wild chimpanzees were lacking, but they observed that both male and female adults within these groups regularly engage in play. Their playful interactions typically involve physical activities like wrestling, mock biting, slapping, pulling, and chasing. The positive essence of these encounters is highlighted through “play faces” and panting sounds, which bear resemblance to human smiles and laughter.
“Although adult play between individuals was not an everyday activity, it consistently appeared under particular circumstances,” Samuni notes.
To gain insights into the role of play in chimpanzee societies, they assessed the play behavior of 57 adult chimpanzees. The team found that these chimpanzees were more inclined to engage in social play before participating in group tasks, such as hunting monkeys or defending their territory from outsiders. Those that played together were more likely to collaborate in these activities, suggesting that play may signal a readiness for cooperation and promote group effort.
When chimpanzees engaged in play with just one other partner, it usually involved close companions, highlighting the strong association between play, familiarity, and trust. Additionally, play occurred more frequently during periods of heightened social stress, like competition for mates or after recent conflicts. This leads researchers to propose that play could serve as a mechanism to alleviate tension and mend disputes.
The results from the studied chimpanzees may not universally represent play behaviors in other chimpanzee populations. Samuni notes that chimpanzees exhibit behavioral diversity and flexibility, with different groups demonstrating specific strategies and behaviors. The high level of adult play in this particularly cohesive population reinforces the idea that “communities characterized by coherence and tolerance may also show increased rates of adult play,” Samuni states.
For their future research, they aim to explore how play among the Taï Forest chimpanzees contrasts with that in other groups. They are also interested in determining whether chimpanzees intentionally choose to play as a strategy to enhance interaction or if the benefits of play naturally encourage cooperation without any conscious intention from the chimpanzees.
