Homosexuality is very divided topic. Some people are completely open and welcoming to the LGBTQ+ community. While others are more conservative in their views and consider it immoral. In many countries, like in the Middle East, it’s even considered a crime. Sometimes punishable by death.
Today, LGBTQ+ rights are still being fought for. In many countries, people of this community still aren’t seen as equals to heterosexuals. But they are. No matter what your sexual orientation, every one of us is human. Just like any other behaviour, homosexuality has evolved over time. It’s a natural part of life.
“It is an expression of biodiversity” say Professor Daniel Pincheira-Donoso, an evolutionary biologist from Queen’s University Belfast. He has been fascinated for years by the topic of homosexuality and has conducted work on how this behaviour has evolved. “Some things are big and some things are small. Some things have fangs, some do not, homosexuality is exactly the same” he continues. However, homosexuality today is still being discriminated against.
Some people have the belief that being gay is only seen in humans or call it unnatural. This could not be further from the truth. Homosexuality is seen all throughout the animal kingdom. “More than 1000 species have been recorded so far with proper expressions of it” Daniel says. “We see the behaviour in invertebrates, vertebrates. It’s everywhere” he emphasises. It’s a normal way of life for many other species on this planet.
Like any other behaviour, both nature and nurture play important roles in its evolution. Across the animal kingdom, genes have been identified that play a role in causing homosexual behaviours. “Those genes are the ones that allow a male to identify another male” explains Daniel. “If those genes are inactivated or altered, then males lose the capacity to see who is a male. So genetically they become homosexuals.” This evidence could suggest a more genetic reason to homosexuality.
An interesting phenomenon seen in humans is known as “The Big Brother Effect.” Daniel sheds further light on this. “When mothers have many boys in a row, normally the fourth or fifth is likely to be homosexual.” Why this phenomenon is seen is still unknown. “There is hypothesises that mothers develop some kind of special way of dealing with hormones that can affect the development of a child that becomes homosexual as a boy.” He then draws on his own experience to share some evidence for this fascinating effect in his own family. “I have five brothers and my fifth brother is homosexual” he says.
The evidence for a genetic basis of homosexuality in humans is unclear. It is also hard to test whether this is true as we can’t ask new born babies their sexual orientation. A more behavioural theory can also explain this sexuality. Daniel explains homosexuality as possibly a more plastic behaviour. This essentially means that it is flexible, that some individuals are never truly homosexual.
“In some species, young males tend to be rejected by females because they are not experienced enough when mating. So they learn to mate by becoming homosexual with other young males” Daniel says. “When they have trained, females accept them. A young male who is starting to mate can damage a female and do many things that females reject.” This is evidence that the behaviour is more plastic.
In many species, homosexuality can come around to resolve social conflicts. “It happens in some primates where there is a dominant male, and there is a male who is not as dominant. When they engage in a conflict, the dominant male can kill the younger, less dominant male” Daniel says. “Sometimes the younger male offers himself to have homosexual sex with the dominant male to be okay with them. It solves the social conflict” he continues. In doing so, the younger male, survives.
He also mentions that this behaviour can be seen in female primates to resolve conflicts over spots for food and help them bond. “Those cases are all plastic responses” Daniel explains. And if we look back into the historical literature, many human societies permitted homosexuality for social reasons. Most famously in Sparta, where it was actually a bonding activity in the military.
There are other examples where homosexuality is used to resolve social conflicts in humans. All we need to do is look at prisoners. “You could be the toughest more heterosexual guy and if you go to prison and someone puts a knife on your neck and says ‘you’re going to be my boyfriend’ you obviously agree” explains Daniel. “You agree to be homosexual for your time in prison. You can choose not to do it and be killed. It’s exactly the same as the apes” he continues. So by using prisoners as examples, we can see that there are parallels in our behaviour and our ape cousins.
Like all animals, how you are raised and taught by your parents affect your behaviours. Daniel discusses whether this also has an effect on the expression of homosexuality. “Children grow up with the idea that girls have to wear dresses and like dolls. Boys wear jeans and like trucks. You grow with those prejudices and constraints” he says. “If parents provide the developmental environment where children can play with dolls if they’re a boy, they develop that social flexibility that may make them more likely to be homosexual. Because your developmental environment provided you with the freedom to do that without being punished” he continues.
“What is straight? A line can be straight, or a street, but the human heart, oh, no, it’s curved like a road through mountains.”Tennessee Williams
Despite all these theories into the evolution of homosexuality, it’s a subject that has confused scientists for years. It is what’s known as an “evolutionary paradox.” Evolution works on sexual reproduction to pass on genes to the next generation. Given this, non-reproductive sex, like that displayed in homosexuals, seems nonsensical as it involves dedicating time and energy towards an activity that does not contribute towards your reproductive success. But even though this type of behaviour is seemingly pointless in terms of evolution, homosexuality is still seen across a wide variety of species.
So why might this behaviour still be selected for if it is not evolutionary beneficial? “There is the assumption that homosexuality is a behaviour you have for your entire life. And that’s where it goes wrong” says Daniel. As mentioned before, homosexuality can be a plastic and not seen throughout someone’s life. “There are cases when people are young, they are more flexible about being homosexual. And as they grow older, they marry with the other sex” he continues. “You cannot assume that homosexual individuals will always be homosexual. That’s why it keeps being passed on.” Suggesting that it may be passed down more passively through generations.
Natural selection acts as a watchdog and filters out costly traits. “If a gene is not costly to you, those traits can be passed on simply because natural selection is blind to it” Daniel explains. These are known as vestigial traits. “If homosexuality is not costly and provides you social benefits, like solving conflicts, then there’s no reason why natural selection would act against it” he goes on to say.
There are benefits to having homosexual individuals in the population, which may also explain why it’s still selected for. One of the most popular explanations for the evolution of homosexuality is that it came about through kin selection. It’s based on the idea that an individual can increase their reproductive success substantially by helping relatives who share their genes reproduce, even if they don’t do so themselves. This can be seen in some societies like Samoa.
In Samoan cultures, there is a third gender that is called “Fa’afafine”, which translates to “in the manner of a woman.” Those in this third gender are usually feminine androphilic males and can be assigned to it at birth. This culture is very common across the Samoan islands and has been going on for as long as the people of the country can remember. The Fa’afafine role is to help the community with tasks usually conducted by females, like childcare and cleaning, but with the strength of a male. There is evidence that shows higher reproductive rates in families with a Fa’afafine member. Despite being more non-binary than homosexual, it still supports this idea that homosexuality could have evolved from kin selection.
The idea of a fluid sexuality may be the best explanation as to why homosexuality is still being selected for. “Bisexuality may actually be the norm for humans” says Daniel. “By pursuing homosexual mating in addition to heterosexual mating, individuals achieve not just reproduction, but also social benefits orientated around the same sex.”
The origins of homosexuality are greatly disputed and generally unknown. What is known is that homosexuality is more common than we think. It’s part of what makes this world so fascinating and adds to the diversity of life. In humans however, some societies still do not welcome this way of life.
We need to move away from these ignorant and medieval points of views of homosexuality and try to normalise the behaviour. We need to fight for humans to be whoever they want to be and love whoever they want to love.
“We need not only to respect, we need to love every expression of biodiversity that we have the luck to see. One of them is homosexuality” concludes Professor Daniel. “The only species on earth that expresses homophobia is humans. Homosexuality is natural, homophobia is extremely unnatural.”