Female bonobos, one of the closest living relatives to humans, have a rare kind of power – they dominate males, even though they are smaller and physically weaker. Scientists say this is because they form alliances, helping them win most fights against their male counterparts.
Female bonobos in the Democratic Republic of Congo won 85 percent of conflicts with males over a period of 30 years, a study published this week in the journal Nature Communications Biology found.
American and German scientists studied six bonobo communities in the DRC, the only country where these great apes live in the wild.
Coalition power
Female bonobos form quick, coordinated alliances – called coalitions – that give them an edge in conflicts with males.
“We have found what everybody already knows – that when you work together, you’re more successful and you gain power,” Martin Surbeck, lead author of the study and a behavioural ecologist at Harvard University, told National Geographic magazine.
This is very different from chimpanzees, the sister species of bonobos, where males dominate all females once they reach adulthood.
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“In bonobo communities, females have a lot to say. And that’s very different from chimpanzee communities where all adult males outrank all females in the group, and where sexually attractive females receive a lot of aggression by the males,” Surbeck added.
The study also found that these female alliances tend to form quickly, especially in response to male aggression.
Barbara Fruth, a behavioural ecologist at Germany's Max Planck Institute of Animal Behavior and co-author of the study, said the coalitions are a powerful way for females to assert themselves.
“It’s a ferocious way to assert power. You know why these males don’t try to overstep boundaries,” Fruth said.
Group variations
Female dominance was not the same in every group or at every point in time. While females often had the upper hand, this varied depending on the community and the year.
In 1998, females in the Eyengo group never lost a fight to a male. In Kokolopori in 2020, they won 98.4 percent of conflicts. But in Ekalakala in 2016, females won just 18.2 percent of the time.
“There is substantial variation in this trait of female power within groups, and we found that coalition formation in females seems to explain a lot of the variation,” said Surbeck.
These coalitions allow females to control important parts of life – they choose their sexual partners, decide when to reproduce, and get first access to food like fruit.
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Zanna Clay, a primatologist at Durham University who was not involved in the study, told National Geographic: “The degree of group variation in female coalitions and female power between bonobo communities was one of the most fascinating findings from this study. This challenges the ‘one-size-fits-all’ view of our closest cousins.”
The researchers tested three possible reasons for female dominance – self-organisation, control over reproduction, and coalition building.
The study confirmed that coalitions were the key.
Looking to our past
The behaviour of bonobos offers clues about how early humans might have lived.
“These data also provide support for the idea that humans and our ancestors have likely used coalitions to build and maintain power for millions of years,” said Laura Simone Lewis, a biological anthropologist at the University of California, Berkeley, who was not involved in the research.
Surbeck agreed. “It tells us that male dominance and patriarchy is not evolutionarily inevitable,” he said.
The researchers say their findings show that cooperation – not just strength – can shape social power, even in species as closely linked to us as bonobos.
