February 19, 2014
THE EVOLUTIONARY PUZZLE OF HOMOSEXUALITY:
Since the early 1990s, researchers have shown that homosexuality is more common in brothers and relatives on the same maternal line, and a genetic factor is taken to be the cause. Also relevant – although in no way proof – is research identifying physical differences in the brains of adult straight and gay people, and a dizzying array of homosexual behaviour in animals.
But since gay and lesbian people have fewer children than straight people, a problem arises.
“This is a paradox from an evolutionary perspective,” says Paul Vasey from the University of Lethbridge in Canada. “How can a trait like male homosexuality, which has a genetic component, persist over evolutionary time if the individuals that carry the genes associated with that trait are not reproducing?”
Scientists don’t know the answer to this Darwinian puzzle, but there are several theories. It’s possible that different mechanisms may be at work in different people. Most of the theories relate to research on male homosexuality. The evolution of lesbianism is relatively understudied – it may work in a similar way or be completely different.
So, basically, we don’t have a clue.