Females were able to overpower male gorillas.

A new study into gorilla relationships has further challenged traditional understandings of the male power narrative.

Behavioural observations have revealed that female gorillas are able to overpower males, even where there are biases in size and strength.

The findings have supported theories, first made over 50 years ago, which challenged the idea that male mammals have universal social power over female mammals. Although spotted hyenas and some species of lemur were initially considered exceptions to rule, growing evidence suggests a more complex situation.

Some research suggests that these species instead sit at one end of a continuum of intersexual power dynamics, from strictly male-based to strictly female-based.

The new gorilla study, from researchers at the Max Planck Institute for Evolutionary Anthropology and the University of Turku, aimed to develop on this work. The team sought to investigate the female-male power relationship, challenging theories that there is male-biased power over females.

The theory comes from the extreme male-biased asymmetries that gorillas exhibit in body and canine size, enabling them to show male-biased power over females.

Researchers conducted behavioural observation over three decades and four social groups, examining the relationships between wild mountain gorillas. 

The observations revealed that almost all the female gorillas in a multi-male gorilla group could overpower at least one male. Despite them weighing half as much as their male counterparts, female gorillas were able to win one in four conflicts and overpower one in four of the non-alpha males.

One theory is that the alpha male gorillas are supporting the female gorillas to overpower the other males. Similarly, another theory is that the non-alpha males are yielding to the females to keep their place in the group.

However, another theory suggests the female gorillas are motivated by gaining priority access to food resources over the males they fight. This could contradicts suggestions that females and males compete over different resources – with previous theories stating females fought over food, while males fought over females.

Martha Robbins, director of the long-term Bwindi mountain gorilla research project, said: "Our results showed that females were more likely to outrank younger and older adult males, which are still so much larger than adult females.

“This suggests that other mechanisms influence female-male power relationships besides basic size and strength."

The full study can be found in the journal Current Biology.

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