Female bonobos stay in charge even though males are stronger

Among the animal kingdom’s many mysteries, few are as fascinating as bonobos’ social lives.

Often called the “hippies” of the primate world, bonobos have long intrigued scientists with their peaceful societies and strong female alliances. Unlike their more aggressive chimpanzee cousins, bonobos embrace cooperation over conflict.

Yet, a deeper puzzle hides within their gentle reputation. Female bonobos dominate social structures, even though males are physically larger and stronger. This unusual dynamic stands in stark contrast to most mammals, where strength usually rules.

Recent research finally sheds light on how bonobo females turned the tables.

Female bonobos control social bonds 

In bonobo groups, females take the lead in reproduction. They decide when and with whom they mate. If a male attempts an unwanted advance, the female easily parries him. Males know better than to push further, respecting the females’ decisions without violence.

This female control extends beyond the bedroom. High-value resources, like fresh kills or prized fruits, also rest in female hands. They feed leisurely on the ground while males hover anxiously in the trees.

Martin Surbeck from Harvard University noted that this behavior is “totally bizarre for an animal like a bonobo.”

Normally, larger body size would give males the upper hand. In most mammals, males dominate food, mating, and status by sheer force. Bonobos, however, defy this rule in surprising and illuminating ways.

Three ideas explain female power

Understanding bonobo society required examining three competing ideas. First is the self-organization hypothesis. It suggests that males could lose dominance over time due to repeated conflict losses.

In addition, the reproductive control hypothesis argues that female hidden ovulation limits male control over mating. Furthermore, the female coalition hypothesis proposes that solidarity among females built power.

“There were competing ideas for how, none of which had ever been tested in wild bonobos living in the jungles in which they evolved,” said Barbara Fruth of the Max Planck Institute. To settle the debate, the researchers turned to long-term field data.

Over thirty years, scientists collected observations from six bonobo communities across the Democratic Republic of the Congo. The patterns they uncovered would finally bring clarity to this evolutionary enigma.

Female alliances turn the power balance

The evidence pointed overwhelmingly to one answer: coalitions. Female bonobos gained their power not by physical strength or reproductive tricks but through alliance-building. In 85% of observed coalitions, females banded together to target males.

“It’s exciting to find that females can actively elevate their social status by supporting each other,” explained Surbeck. These alliances were not casual. They formed quickly, often within seconds of a triggering event, such as male aggression toward infants.

Once a coalition formed, its effect was loud and unmistakable. Screams pierced the forest so sharply that “you have to block your ears,” Fruth recalled. Targeted males faced not just humiliation but sometimes severe injuries, forcing them to flee groups for days or weeks.

Female power varies between bonobo groups

Despite the strength of female coalitions, dominance was not absolute. Researchers found wide variation across bonobo communities. In some years, a male even held the top rank, particularly when supported by a powerful mother.

“It’s more accurate to say that in bonobo societies, females enjoy high status rather than unchallenged dominance,” said Fruth. Mothers played a crucial role. In communities where adult males had living mothers, males sometimes rose higher in the hierarchy.

Other communities, especially those with frequent female coalitions, saw females consistently outranking males. The key factor was the frequency and strength of female alliances, not the number of males or other demographic shifts.

Theories to explain female dominance

The researchers thoroughly tested the alternative hypotheses but found little support. The self-organization hypothesis suggested that a higher proportion of males would lead to female dominance. However, the data showed no significant relationship.

Likewise, the reproductive control hypothesis, based on hidden ovulation and prolonged fertility signals, did not fully explain the female advantage. Synchronization of sexual swelling among females did not correlate with greater female power.

While hidden ovulation may reduce male aggression overall, it does not guarantee female dominance. It is coalition-building, not mating strategies, that most consistently empowers bonobo females.

Female bonobos rise through alliances

Female coalitionary aggression showed a strong association with female power across communities. Where females more often banded together, they won more conflicts against males and held higher ranks.

This finding highlights a striking evolutionary strategy. In most mammals, including primates, females rarely form aggressive alliances. Bonobos stand apart, using group action rather than individual strength to tilt power dynamics.

Interestingly, even in the absence of kinship ties, immigrant bonobo females built strong social bonds. This behavior challenges long-held assumptions that cooperation depends on genetic relatedness.

Consequences for male behavior and society

Bonobo males, facing strong female alliances, shift their strategies accordingly. Instead of aggression, males invest in maintaining peaceful relationships with females. Coercive mating, common in many primates, is rare among bonobos.

Males gain reproductive success by staying close to receptive females and avoiding conflict. In this environment, violence backfires while cooperation wins mates. Such dynamics reveal an evolutionary route where peace, not aggression, yields greater success.

In communities with strong female coalitions, males sometimes become isolated after aggressive incidents. Some males even leave the community temporarily after facing intense female retaliation.

Unity beats physical strength

The bonobo case challenges the traditional view that strength alone governs social structures. Instead, social support networks play a vital role in shaping dominance hierarchies.

Surbeck’s research adds to a growing body of evidence suggesting that female empowerment in mammals can arise through multiple pathways. In spotted hyenas, for example, female dominance stems from social support and reproductive control.

Fruth reflects, “I’m still puzzled why, of all animals, bonobos were the ones to form female alliances.” Although the reasons remain mysterious, the findings offer hope. They hint that even in fiercely competitive environments, solidarity can surpass force.

The future of bonobo research

While much progress has been made, questions linger. How do individual personalities affect coalition formation? Why do some communities show stronger female solidarity than others? What environmental or historical factors shaped these behaviors?

Future studies will aim to unravel these complexities. Researchers also hope to explore how these findings could shed light on human social evolution. After all, bonobos, along with chimpanzees, are our closest living relatives.

Understanding the roots of power, cooperation, and gender relations in bonobos might help us reflect on our own evolutionary journey.

A different kind of power

In the end, bonobo societies remind us that power does not always stem from size, strength, or aggression. Sometimes, it arises from unity, shared purpose, and rapid, courageous action.

Among bonobos, females carved a unique path – one built not through fear but through collective strength. It is a path that challenges assumptions, sparks wonder, and perhaps, whispers lessons to our own species across the evolutionary gulf.

The study is published in the journal Communications Biology.

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