Is it true that male animals are dominant over females? Previous studies have often found male-biased power in primates and other mammals.
Author
- Louise Gentle
Principal Lecturer in Wildlife Conservation, Nottingham Trent University
A new study , investigating physical encounters between members of the same species in 121 primates (around a quarter of all primate species) found that half of all aggressive contests were between males and females. But males won these contests in only 17% of primate populations, with females dominating in 13% - making it almost as likely for females to dominate males.
The remaining 70% of primate populations showed no clear-cut dominance of one sex over the other. This study may have shown different results to previous research because it assessed individual contests rather than categorising species based on their social structure and physical attributes.
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The new study found male dominance, where males have a greater ability to influence the behaviour of the opposite sex, to be prevalent in primate species where the males are much larger than the females. This enables males to gain dominance through physical force or coercion. It was also widespread in species where males have weapons and mate with lots of females.
This is typical of African and Asian monkeys and the great apes, such as gorillas. Weighing in at around 200kg, a silverback male can be twice the size of the females within his troop. Male gorillas also have large canine teeth that can seriously injure or even kill other gorillas.
Male dominance often twins with weapons throughout the animal kingdom , - horns, antlers, claws or tusks . The largest antlers ever known were those of the now extinct Irish elk, spanning lengths up to 3.5m.
Female dominance
Female power was seen in primate species that had a scarcity of females, one exclusive sexual partner, similar sized males and females but did not have bodily weapons, according to the new study. These are all factors that give females more choice over who to mate with.
Female dominance was also seen in species where fighting with a male was less risky for the dependent offspring of females. For example, some primates "park" their young on their own in nests while foraging, rather than carrying them around. If a mother is holding her baby when she's attacked, she may submit to protect her young.
Finally, matriarchal societies were common in species that live primarily in trees, which makes it easier to flee an attacker.
Female-dominated species were more likely in lorises, galagos and lemurs. So, contrary to the film Madagascar where King Julien is the king of the lemurs, females are, in fact, in charge . In the ring-tailed lemurs , females control access to food and mates, and maintain the dominance hierarchy where males are often at the bottom.
This is also true of bonobos, the closest relatives of humans . Although male bonobos are larger, females form coalitions to overcome the physical power of the males and force them into submission. This show of solidarity has also been shown in humans.
Think of how the suffragettes campaigned for women's rights to vote in the UK. Or more recently, how women demanded new safety measures after Sarah Everard was murdered by Metropolitan Police officer Wayne Couzens in 2021.
Although female dominance has been documented less often in the wider animal kingdom, there are some examples that defy expectations. Spotted hyenas have a matriarchal society where females dominate the clans. They even have a pseudo-penis that they erect to indicate submission to more dominant individuals.
Naked mole rats have a queen that gives birth to all of the young while her offspring find food and defend the nest. The males are subordinate to the queen, but so too are the other females. In fact, the queen bullies the other members of her colony so much that the females are all rendered sterile through stress.
But what about the 70% of primate species that were found to show no dominant sex bias in the new study? These were largely the South American monkeys such as marmosets, tamarins and capuchins, that are generally small, live in trees, are social and omnivorous.
They also tended to have a prehensile tail that helps them grasp things. The ecology of these species fall in the middle of the male and female dominated species, with size difference and weapons being neither extreme nor absent, mating systems being neither polygamous nor monogamous, and the frequency of females being nether abundant nor rare.
The absence of a definitive sex-bias in dominance found in the majority of primate species may be a result of the rarity of contests between males and females, or because males and females were both equally likely to win. Nevertheless, dominance varied within species. For example the percentage of intersexual contests won by female patas monkeys ranged from 0% to 61%, depending on the population studied.
What does this mean for humans?
Human traits are not skewed towards those of male-dominated societies in other primates. We may not live in trees but males do not have natural weapons. Males are not always bigger than females, females do not tend to outnumber males and our sexual habits are varied.
Humans are actually more aligned to the 70% of species that show no clear distinction in sex biases, where species of either sex can become dominant. Let's see which way evolution takes us.
Louise Gentle works for Nottingham Trent University.
