The new science changing ideas of sex, gender and sexuality

In a study of 1000 mammals ranked on their propensity to murder one another, the humble meerkat came out on top.

"Their societies are intensely homicidal," said Lucy Cooke, a zoologist who specialises in evolution and animal behaviour.

"Every meerkat has a one in five chance of being killed by a member of its own species - most likely its own mother or sister.

"Meerkat society is predicated on vicious, brutal competition between females that will readily kill and eat each other's pups in order to monopolise all of the reproductive resources.

"Darwin said all females were imbued with a natural maternal instinct and they're all much the same at it, but actually there's huge variety to that experience.

"A lot of it requires some pretty aggressive, dominant and vicious behaviour - as you see with the meerkat."

Cooke, whose latest book 'Bitch: A Revolutionary Guide to Sex, Evolution and the Female Animal' will form the basis of a presentation at this year's Edinburgh Science Festival - which launches today - said for too long female animals were "marginalised and misunderstood by the scientific patriarchy".

Lucy Cooke said female meerkats are 'intensely homicidal', contrary to their cuddly image (Image: BBC)

Much of the problem, she says, is a hangover from what was considered culturally acceptable in the Victorian era.

"Darwin was a genius, but he was also blinded by the culture of the time. So when he came to describe the sexes he saw them as radically different.

"Males were the dominant drivers of evolutionary change. They were promiscuous and competitive and aggressive, whereas females were relegated to a footnote of this macho main event.

"They were just passive, coy, and submissive.

"And because Darwin defined females in that way, all the scientists who followed in his wake for at least 100 years, and even many to this day, still believe these stereotypes which were really rooted in cultural bias and not in science.

"The problem with that - the way we view female animals - is that we are always looking to the animal kingdom for clues as to our own behaviour, so these tropes and stereotypes exist within the animal kingdom and then get thrown back at women."

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Cooke, who trained under the famous evolutionary biologist Richard Dawkins at Oxford University, said that the tide began to turn in the 1980s when female scientists started going into the field themselves and observing that some female animals were "mating with every male in the area", contrary to long-standing expectations that they would have to be chased.

"Instead of ignoring it, they questioned it, and by doing so they redefined what it means to be female," said Cooke, although she stressed that even now males remain "much more studied than females" in the animal kingdom.

It is not just sex role stereotypes that science is starting to overturn, however. Ideas about gender and sexuality are also being questioned.

One example is the anemonefish, which can have gonads while behaving as a female.

The discovery, revealed by researchers at the University of Illinois in 2019, is the first known example of an animal undergoing a sex change in the brain before the sex organs.

In anemonefish colonies, the female is dominant - she protects the nest from predators while the male partner (they mate for life) tends to the eggs.

If the female dies or disappears, males will transition.

When the neuroscientists in Illinois put 17 pairs of male anemonefish into a tank, they found that - within hours - two emerged as dominant and began behaving as female.

However, changes in the sex organs could take months.

"The change happens first in the brain," said Cooke.

"The fish are almost immediately recognised as females and behave as females.

"If you asked that fish what sex it is, it would say 'female', but its gonads take up to a year to catch up. The gonads remain male but the fish thinks and behaves as a female.

"That has huge implications because there's a lot of discussion around whether sex and gender can be different.

"Here's a fish where you can see that it is.

"There is a lot for us to learn about the complexities of sex and gender and sexuality, and what the animal kingdom shows us is just how gloriously complex and plastic it is."

Sexual activity in the animal kingdom also runs counter to the perception that it is only motivated a reproductive impulse.

"In bonobos, females have a lot of sex with each other, as do the males," said Cooke.

"The idea that sex is just for procreation is a Victorian idea.

"We shouldn't be surprised to see that animals have a lot of same-sex sexual activity because sex has a lot of roles.

"It's great for bonding and forging relationships."

Ideas around sex, gender, and sexuality have been in flux during a period when research into animal behaviour has also revealed unexpected diversity (Image: PA)

One surprise for researchers came when they realised that female albatrosses can form same-sex couples to raise young.

Cooke visited the albatross colony in Hawaii where the discovery was made when she was researching her book.

"This is an albatross colony that had been studied for 50 years and it was always assumed that the couples on the nest were male and female because the birds are identical, but then it was discovered that a third of the nests were female-female couples.

"Obviously the females still need sperm in order to fertilise their eggs so they were mating with other albatross 'husbands' but then shacking up with another female in order to raise the chicks because there was a shortage of males in that particular colony."

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While it would be wrong to anthropomorphise animals with terms like 'bisexual', the level of fluidity found in the animal kingdom also raises questions about what is really 'normal' in humans.

Dr Julia Shaw, a psychological scientist at University College London who has delved into the topic in her book, 'Bi: the hidden culture, history and science of bisexuality', is keen to "demystify" the subject during a talk at the Edinburgh Science Festival.

She says the conversation around bisexuality is "about 20 years behind homosexuality".

"We see that in terms of the bisexual penalty in workplaces," said Shaw.

"People who make it clear in some way on a job application that theyre bisexual will generally be offered less money than if they say nothing, or say that they're gay."

Dr Julia Shaw said perceptions of bisexuality in men and women had been shaped by cultural norms (Image: Dr Julia Shaw)

Discrimination coalesces around a few recurring prejudices, says Shaw: whether bisexuality is "real", and a suspicion that bisexual people are much less likely to be monogamous and much more likely to be promiscuous.

She said: "We know from research that one of the reasons why people rarely say they're bisexual, especially women, is because they're perceived as 'sluts'.

"Bisexual women are twice as likely as lesbians or straight women to be sexually assaulted and that's probably partly because they're seen as constantly sexually available.

"With men, bisexual men are often seen as actually gay.

"Either way there are negative stereotypes, and that's because of that very strong connection that when you say 'bisexual', people think of sex, they think of threesomes - they're not thinking of an identity."

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In fact, Shaw thinks that most humans at least have the capacity for attraction to multiple genders, based on responses to the Kinsey Scale - a spectrum of sexual orientation first developed in the 1940s.

She said: "If you ask people to rank themselves on the Kinsey Scale between zero and six - zero being exclusively heterosexual desires and six being exclusively homosexual desires, and all the numbers in between what we would consider the bisexual spectrum - you find much higher rates than if you just ask people 'are you bi?'.

"Those same people who would say 'no' you often find putting themselves on a two or a three on the Kinsey scale."

She also notes that while women today are twice as likely as men to identify as bisexual, in the 1990s the roles were reversed. 

"When research on this started, it was consistently said - in the same way that people now say 'obviously there are more bisexual women' - people used to say 'obviously more men are bisexual'.

"So there are obviously social aspects to this which have a huge influence on how people use that label, and think about their own sexuality and sexual behaviour.

"The main difference I think is the acceptance that women have sexuality, that they have sexual interests and desires.

"For a long time that was simply denied. It was seen that sex and sexuality revolved around men."

'Bitch: A Revolutionary Guide' is at the Edinburgh Science Festival on April 7

'Demystifying BiSexuality' is on April 14