A recent study published in the journal Animal Behaviour has shown that after a male bonobo violently attacks a female, a group of female bonobos will form a coalition to attack that male who committed the assault.
The research team from Kyoto University in Japan came across this behaviour over their four years of detailed observation of the species in the wild, in the Democratic Republic of Congo. Unlike their closest relatives the chimpanzees, who form male dominant social hierarchies, the bonobos are known to form relatively peaceful matriarchal groups.
"We may have uncovered one of the ways in which females maintain a superior status in bonobo society," says lead author of the paper, Nahoko Tokuyama, in an official press release.
Their research also found older female bonobos championed these coalitions, seeking to protect younger female bonobos from male attacks. Younger females were the most common victims of the male bonobo attacks.
"Young females have a lower social status than males, but protection from older females seem to let young females join the group without fear of being attacked by males. By controlling aggression by males in this manner, females maintain overall superiority in the social hierarchy,” Tokuyama says.
The researchers observed any older female would come to the aid of a younger bonobo regardless of who they were
Their observations also revealed older female bonobos had a greater chance of winning a one-on-one fight against a male bonobo. And when an alliance of females attacked a male, the females always won.
This behaviour from the older females didn’t appear to be swayed by nepotism or closer relationships they may have formed with certain younger females. The researchers observed any older female would come to the aid of a younger bonobo regardless of who they were.
Though potentially an evolutionary mechanism to combat male harassment within their species, Tokuyama and his team have theorised this behaviour may not be completely altruistic.
"It's beneficial for the older females as well, because the younger females start spending more time with them in hopes of getting protection. This way, the older female can give her son more opportunities to mate with the younger females. Such partnerships might in fact be the very factor that fosters gregariousness and promotes tolerance among females," Tokuyama says.