Wild chimpanzees can perform social grooming and social play behaviors simultaneously

Reliable evidence was obtained of the simultaneous performance of social grooming and social play behaviors by individuals among wild chimpanzees of the M group in Mahale Mountains National Park. I observed three cases of this performance: in an old female, a young female, and an adult male. While the agent was grooming the back of an adult bimanually, an infant or a juvenile approached the agent. The agent then started playing with the infant/juvenile using only the right hand, while simultaneously grooming the back of the adult with the left hand. In one case, an old female continued the simultaneous performance for about 1 min. Such performances probably occur at low frequency because they are not often required. The similarity in the neurobiological bases and the functions of social grooming and social play behaviors, both of which include repetitive contact with the body of another individual, may facilitate their simultaneous performance.