Bonobo moms play an active role in helping their sons find a mate

MAY 20, 2019

by Cell Press

Many social animals share child-rearing duties, but research publishing May 20 in the journal Current Biology finds that bonobo moms go the extra step and actually take action to ensure their sons will become fathers. From physically preventing other males from mating to bringing their sons in close proximity to ovulating females, bonobo moms bring new meaning to the notion of being overbearing—but in so doing, they increase their sons' chance of fatherhood three-fold.

"This is the first time that we can show the impact of the mother's presence on a very important male fitness trait, which is their fertility," says Martin Surbeck, a primatologist at the Max Planck Institute for Evolutionary Anthropology. "We were surprised to see that the mothers have such a strong, direct influence on the number of grandchildren they get."

Surbeck and his colleagues observed wild populations of bonobos in the Democratic Republic of Congo, as well as wild populations of chimpanzees in Côte d'Ivoire, Tanzania, and Uganda. They found that while both bonobo and chimpanzee mothers would advocate for their sons in male-on-male conflicts, bonobo moms went the extra mile to aid their sons' copulation efforts. This involved protecting their sons' mating attempts from other males, intervening in other male's mating attempts, and intentionally bringing their sons around fertile females.

The bonobo mothers were also able to use their rank in the bonobo's matriarchal society to give their sons access to popular spots within social groups in the community and help them achieve higher status—and therefore, better mating opportunities. The authors note that these interactions were rare in chimpanzee societies likely because males hold dominant positions over females, making the actions of chimp mothers less influential than those of bonobo mothers.

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