Forget what you thought you knew about alpha males: a major new study suggests that clear-cut male dominance in primate societies is far from universal – and that in many species, females hold equal power or even come out on top.
Researchers spent five years compiling data from 253 primate populations across 121 species to investigate power dynamics between the sexes. Instead of relying on assumptions, they gathered detailed behavioural records – who fought whom, and who won.
“We wanted individual-level observations of who wins fights against whom – not just broad classifications like ‘males are dominant here’,” evolutionary biologist and co-author of the study, Dr Dieter Lukas, told BBC Science Focus. “From that, we inferred how often males and females actually win.”
What they found challenges long-standing stereotypes.
In all, the team observed male dominance, where they win over 90 per cent of contests with the opposite sex, in just 25 of the 151 populations. Female dominance occurred in 16 populations, with the remaining 70 per cent of groups having only moderate or no dominant sex.
“Strict male dominance was really a minority of systems,” Dr Élise Huchard, another of the study’s authors, told BBC Science Focus. “We didn’t expect it to be a majority because we already knew the literature quite well, but under 20 per cent was probably smaller than what we would have expected.”
Intersexual aggression – fights between males and females – was also far more common than previously appreciated, making up nearly half of all adult conflicts.
Lukas said that most studies tend to focus exclusively on either males or females, with few examining the dynamics between them. “But here,” he said, “[intersexual] conflict is actually expressed – it’s frequent aggression between males and females.”
The study also challenges the idea that power always rests on brute force. In many primate societies, female dominance arises not through strength but through reproductive control.
“If a female doesn’t want to mate, the male can’t do anything about it,” Huchard said. “When females do control reproduction, they can use it as leverage – as a power mechanism – towards males.”
Although the researchers are cautious about applying their findings to humans, they say the results point to surprising flexibility in gender roles across our evolutionary cousins.
“We have two closest relatives – chimpanzees and bonobos. One is male-dominant, one is essentially female-dominant,” Huchard said. “So even before we did this study, we knew things weren’t going to be deterministic.”
The findings suggest social hierarchies in primates – and perhaps humans – aren’t hardwired. They’re shaped by environment, group composition, mating systems, and individual relationships. In short, there’s no single blueprint for who holds the power.
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About our experts
Dieter Lukas is an evolutionary biologist focused on social systems of past and present populations from a comparative perspective at the Max Planck Institute for Evolutionary Anthropology. His recent work unravels the fundamental assumptions underlying the field of human behavioural ecology, showing that behavioural variation in humans appears to be constrained by many of the same factors that shape behaviour in other mammals and birds.
Élise Huchard is a researcher at the University of Montpellier in France. Her research focuses on mammalian social behaviour, mainly in the context of long-term studies in natural populations, but also through comparative analyses. She is also chief editor of behavioural and evolutionary ecology for the journal Frontiers in Ecology and Evolution.