Communication and cooperation may have coevolved in the last common ancestor of chimpanzees and humans

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)—An analysis of the bark vocalizations that wild chimpanzees make while hunting suggests that communication and cooperation may have coevolved in the last common ancestor of chimpanzees and humans. The study*, which draws from observations of 227 hunting events conducted by chimpanzees in a Ugandan community from 1996 to 2018, demonstrated that these primates use vocal signals to facilitate cooperative hunts. The study found that chimps who barked before a hunt were more likely to participate and that barks are associated with greater hunter recruitment and more effective hunting. While scientists have known that the abilities to cooperate and to communicate likely coevolved in humans, the evolutionary roots of the relationship between these two abilities has not been clear, including whether its basic building blocks may be found in humans’ closest living primate relatives. To investigate, Joseph Mine and colleagues analyzed data on how 74 chimpanzees used hunting-related bark vocalizations between 1996 and 2018 in the Kanyawara chimpanzee community, located in a national park in Uganda. The researchers used data from 2,398 observations during that period to construct a generalized linear mixed-effects model and applied it to understand whether the apes’ barks were associated with an increased likelihood of individuals participating in a hunt for monkey prey. Mine et al. found that the probability of joining a hunt was considerably higher for chimpanzees that had barked beforehand than for those that had not, suggesting that the bark vocalizations signaled their motivation to participate. Additionally, the researchers found that these vocalizations the group’s behavior as a whole – hunting was more effective when it was preceded by barking, since this meant more chimpanzees were involved.

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