Female mountain gorillas in Rwanda appear to use a strategy familiar to many humans when entering new social situations: they seek out familiar faces. A new study, published Wednesday in Proceedings of the Royal Society B, tracked 56 female gorillas over two decades and found they tended to join groups with females they've known for at least five years or encountered within the previous two years. Lead author Victoire Martignac, an evolutionary anthropologist at the University of Zurich, notes that this behavior may help ease the stress of joining a new group, where newcomers often start at the bottom of the hierarchy. "A familiar female might help reduce this, providing a social ally," adds senior author Robin Morrison, per Smithsonian.
While male gorillas typically disperse by going solo and attempting to start new groups, females must integrate into existing ones—a process that promotes genetic diversity and prevents inbreeding, per the BBC. The study's findings challenge the long-held belief that female gorillas' same-sex relationships don't hold lasting value, given the frequent group changes. Researchers also observed that females tend to avoid males they grew up with, likely to sidestep close relatives. The results were based on data collected by the Dian Fossey Gorilla Fund, which enabled long-term tracking and analysis. Factors like group size or sex ratio didn't significantly influence the females' choices, researchers found. It was the social connections that mattered most.