Quirks & Quarks

Bonobo mothers act as wing-mums for their sons

Mothers help sons get access to females and scare off rival males

Mothers help sons get access to females and scare off rival males

Bonobo mother and son in the Kokolopori Reserve, Democratic Republic of Congo. (Martin Surbeck)
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There are times you want your mother around, and times you definitely don't, and one of those times is when you are on a date. However a new study has revealed that this isn't the case with bonobos.  A male bonobo's best chance of mating successfully is when his mother is nearby and helping out.  

Bob McDonald spoke with Barbara Fruth about this finding.  She's an Associate Professor in Primate Behaviour and Conservation at Liverpool John Moores University, and worked on this study with a team of colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig.

Bonobo mama's boy

The team studied wild populations of bonobos in the Democratic Republic of Congo and compared their social behaviour with wild populations of chimps in Ivory Coast, Tanzania and Uganda.

The mother-son bond is evident here as a bonobo mother grooms her infant son. (Kokolopori Bonobo Research, Barbara Fruth)

Bonobo society is matriarchal, and male offspring stay with their mother's social group. Females typically leave their birth groups and join other groups.

Bonobo mothers are very protective and supportive of their stay-at-home male offspring. 

They support their sons in male-on-male conflicts, but their more important contribution is to their sons' reproductive success.
Bonobo male. (Kokolopori Bonobo Research, Martin Surbeck)
     

Bonobo mothers want to be grandmothers

Fruth and her group observed bonobo mothers facilitating the mating efforts of their sons in many ways. They encouraged young females to hang around, and chased away any male intruders or potential competitors to their sons mating attempts.

Fruth and her colleagues estimate that the presence of the mother makes the likelihood of the son producing offspring three times higher than if she were not around. 

Young bonobo male grooms his mother. (Kokolopori Bonobo Research, Barbara Fruth)

The purpose of this behaviour for the mothers is to increase their own indirect reproductive success. Fruth suggests that this might be part of the mystery of the evolution of menopause. The argument is that post reproductive mothers encourage the dissemination of their own genes by facilitating their sons having more offspring. 

Daughters are on their own

As female bonobos usually leave their birth group to join other groups, they can't receive this kind of reproductive support from their mothers. Fruth said that even in the rare case that Bonobo females stayed with their birth group, they had no special support from their mothers. 

  

Corrections

  • An earlier version of this story stated that Barbara Fruth led this study of bonobo behaviour. She was part of the research team, but not the study leader.
    Jun 28, 2019 10:56 AM ET

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