Young adults maintain many friendships, but as people grow older, they tend to winnow that group down to a select few meaningful relationships.
A recent study published in the journal Science suggests that humans aren’t the only species to get socially selective like that: Chimpanzees do the same. Researchers studied data collected in Uganda’s Kibale National Park over two decades to assess how a group of male chimps’ friendship dynamics shifted over time.
“We found that wild chimpanzees, like humans, prioritize strong social bonds and interacting with others in positive ways as they get older,” Alexandra Rosati, an anthropologist at the University of Michigan and lead author of the study, told Business Insider.
“The older chimpanzees had more mutual and equitable friendships with others, whereas younger adults were more likely to form one-sided relationships where their partner did not reciprocate,” she added.
Emotional reactivity refers to a tendency toward strong, uncontrollable emotional reactions. For example, Rosati added, younger chimpanzees get pulled into fights during social events, “whereas the older chimpanzees may be able to regulate themselves and not get drawn into the fray.”
Stabilizing their emotions, the study authors wrote, serves aging chimps well: It can help them form cooperative alliances with younger males and may improve mating chances later in life.