Female dominance in primates is more common than we thought

Gender dynamics among primates have long fascinated both scientists and the public. Many people assume that male dominance over females is natural across primates, a belief that also shapes how we think about human gender roles. However, a new study challenges this view.

Conducted by researchers from the University of Montpellier, the Max Planck Institute for Evolutionary Anthropology, and the German Primate Center, the work sheds light on the surprising flexibility of power relations among primates.

The findings reveal that neither male nor female dominance is universal. Instead, power shifts depend on factors such as ecology, reproductive strategies, and social structures. The study spans 253 populations from 121 primate species, making it the largest of its kind.

The results call for a reconsideration of our assumptions – not only about other primates but also about ourselves. The study highlights how gendered power dynamics emerge through complex, evolving interactions.

Why power matters in primates

The researchers examined patterns of aggression between males and females in primates. They discovered that nearly half of all aggressive encounters occur between opposite sexes.

This finding contrasts with previous studies that focused mostly on same-sex competition. These older views assumed that males and females compete for different resources, leading to separate social hierarchies.

“The observation that, in most populations, any given individual is more likely to be involved in a fight against another individual of the opposite rather than the same sex highlights that the battle of the sexes is common in other animals,” said Dieter Lukas from the Max Planck Institute.

The researchers then studied the outcomes of these conflicts to identify whether males or females tend to dominate.

Male dominance is rare in primates

Traditionally, many assumed that male dominance is the default in primate societies. Iconic cases like female-dominant bonobos or lemurs were seen as rare exceptions.

Yet this study revealed a more complex picture. Among the 151 primate populations with quantitative data, only 17 percent showed strict male dominance. In comparison, 13 percent showed strict female dominance.

The remaining 70 percent of populations displayed moderate or no clear dominance by either sex.

“Recent research started to challenge the traditional views of male dominance being the default status, and our study now provides a more comprehensive exploration of variation in intersexual dominance relationships,” noted Peter Kappeler from the German Primate Center.

The research marks a major shift from old assumptions, showing that rigid male dominance is far less common than once believed.

When female primates take charge

To explain these varied outcomes, the researchers tested five hypotheses. The strongest support emerged for the reproductive control hypothesis.

In species where females gain more control over reproduction, they are more likely to dominate socially as well. This pattern appears in species that are monogamous, arboreal, or where males and females are similar in size.

In such species, females can often reject male advances. They also tend to live in environments that allow them to avoid physical coercion.

Female dominance also flourishes in societies with high female-female competition. This includes pair-living or solitary species where females are territorial and fiercely guard resources.

Interestingly, female dominance often coincides with low sexual dimorphism, short periods of sexual receptivity, and balanced sex ratios within groups.

Where male primates keep power

Conversely, male-biased dominance typically appears in terrestrial, polygynous species with high sexual dimorphism. In these societies, males dominate through sheer physical power.

“Critically, while primate males gain power via physical force and coercion, female empowerment relies on alternative pathways, such as reproductive strategies to gain control over matings,” noted Elise Huchard from the University of Montpellier.

This pattern often involves larger male body size, specialized weapons like large canines, and polygynous mating systems. Terrestrial species are especially prone to this male-dominated structure, as females have fewer opportunities to escape or resist male control.

The findings reveal that the ecological context – whether arboreal or terrestrial – shapes the way power is exercised.

Female power shifts within primates

One striking discovery is that dominance patterns often vary within a species. The study revealed wide-ranging variation in female dominance across different populations of the same species.

For example, in bonobos, females win between 48 percent and 79 percent of contests with males, depending on the group. Other species show similar variation, proving that social dynamics can shift based on local conditions.

Some species even display all three dominance types – female-biased, male-biased, and neutral – across different groups.

The researchers also noted a clear link between evolutionary history and dominance patterns. Great apes and African and Asian monkeys tend to show male-biased dominance, while lemurs and lorises frequently show female dominance. New World monkeys often fall somewhere in between.

Competition and female dominance

Another major finding comes from testing the female competition hypothesis. The study found that species with intense female-female competition often show female-biased dominance.

Such competition appears frequently in pair-living or solitary species where females exclude rivals from resources. Female dominance also tends to emerge in stable social groups where female conflicts over food are common.

Interestingly, ecological harshness and environmental unpredictability were not strong predictors of female dominance, despite past claims to the contrary.

Instead, social structure and mating systems – such as group stability and reproductive strategies – emerged as stronger influences.

Female parenting and primate power

The study also explored the offspring safety hypothesis, which links dominance to parenting strategies. It found that female-biased dominance is more common in species where mothers park their young rather than carrying them constantly.

Species with shorter lactation periods and lower risks of male-inflicted infanticide also tend to show greater female dominance. These traits reduce the cost of engaging in risky conflicts with males.

Interestingly, allomaternal care, where other group members help care for infants, also plays a role in shaping power dynamics.

Social bonds and female dominance

Researchers also tested whether female social bonds, such as coalition formation, explain female dominance. Their findings showed only limited support for this idea.

While female philopatry – where females remain in their birth group – was linked to greater female dominance, this pattern was not strongly tied to coalition formation.

This challenges theories that female alliances drive dominance in species like bonobos. The authors suggest that in many cases, sex-biased dispersal may be a result of dominance structures rather than their cause.

New view of power and evolution

The findings offer a profound shift in how we think about male and female primates – and humans – by revealing that dominance is not fixed by nature but shaped by many intertwined factors.

Female power often emerges through reproductive strategies, social competition, and ecological flexibility. Male dominance, on the other hand, typically relies on brute force, physical coercion, and ecological constraints.

By showing that female dominance is neither rare nor accidental, this research opens the door to new ways of thinking about gender roles.

Ultimately, the study highlights that both male and female dominance can emerge through different routes, depending on specific ecological and social pressures.

The study is published in the journal Proceedings of the National Academy of Sciences.

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