Male bonobos are larger and stronger than females, so researchers have found it puzzling that the female apes enjoy high status in bonobo society. After analyzing three decades of behavioral data, researchers recently shared a study that pinpoints their source of power: female alliances and coalitions.
“Only [among] bonobos, females form coalitions to gain power over males,” the study’s lead author Martin Surbeck of Harvard University told Mongabay by email.
Surbeck said there are other examples of animal species in which females are dominant over males, including spotted hyenas (Crocuta crocuta) and vervet monkeys (Chlorocebus pygerythrus). What sets bonobos (Pan paniscus) apart is how they dominate.
Researchers analyzed 30 years of demographic and behavioral data from six wild bonobo communities in the Democratic Republic of the Congo and found that “the propensity of females to form coalitions against males was positively associated with the degree of power that females had over males.”
While females “often had power over males,” it was not exclusive or consistent. Of the 1,786 conflicts recorded, 61.5% were won by females compared with 38.5% won by males. The majority, or 85%, of such incidents were directed at males, the rest against females.
“To our knowledge, this is the first evidence that female solidarity can invert the male-biased power structure that is typical of many mammal societies,” Surbeck said in a press release. “It’s exciting to find that females can actively elevate their social status by supporting each other.”
The formation of female coalitions was often triggered by male aggression against adult females or their babies. The researchers said further studies are needed to understand the source of conflict, as it wasn’t always clear to the researchers.
Co-author Barbara Fruth with the Max Planck Institute of Animal Behavior has led the LuiKotale bonobo research station for 30 years. In the press release, she said female bonobo coalitions can involve screaming that is so unbearable, “you have to block your ears.” Females have been observed following a target male through the trees as they screamed. “It’s a ferocious way to assert power,” Fruth said. “You know why these males don’t try to overstep boundaries.”
The release said such power allows female bonobos to decide when and with whom they mate. They can also have control of food resources.
Surbeck told National Geographic the study shows that “male dominance and patriarchy is not evolutionarily inevitable” and that “apes and humans are very innovative and flexible in their behavior.”
In the same article, biological anthropologist Laura Simone Lewis, who wasn’t part of the study, said it “could provide insight into how women could build power to better protect ourselves from male violence.”
Bonobos are one of our closest living relatives, so better understanding bonobo society might “help us tremendously to reconstruct where we come from,” Surbeck said.
Banner image of the Ekalakala bonobo group in the Kokolopori Bonobo Reserve in the DRC courtesy of Martin Surbeck/Kokolopori Bonobo Research Project.
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