The findings, published in the Royal Society Journal Proceedings B, external, show how important the relationship between two individual females is in gorilla society.
“Scientifically, I don’t know if I can talk about ‘friendship’,” explained lead researcher Victoire Martignac, a PhD researcher form the University of Zurich. “But we’re showing here that these same sex relationships really matter.”
Moving into different groups is key in shaping the animals’ social structure. It’s something that both males and females do – females will sometimes move several times throughout their lives.
This dispersal, as it’s known, plays a role in avoiding inbreeding, spreading gene diversity and shaping social relationships.
“In the wild it is very important,” explained Ms Martignac.
“But it’s extremely hard to study, because once individuals leave a group, it’s hard to keep track of them.”