Homofili og evolusjon

Hvordan overlever egenskapen «homofili» den evolusjonistiske prosessen som avhenger av at man må spre sine gener mest mulig i best mulig tilpassede individer for at de ikke skal selekteres bort? Homofil sex skaper ikke barn, og dermed kan ikke genene til homofile videreføres. Homofili burde altså vært selektert bort fra menneskearten for lenge siden. Likevel eksisterer det fortsatt homofile. Hvorfor og hvordan?

Ny forskning tyder på at svaret er enkelt:

«It helps to answer a perplexing question – how can there be ‘gay genes’ given that gay sex doesn’t lead to procreation?» says Dean Hamer of the National Institutes of Health in Bethesda, Maryland, who was not involved in the work. «The answer is remarkably simple: the same gene that causes men to like men also causes women to like men, and as a result to have more children.«

The researchers asked 239 men to fill out questionnaires about their families and their past sexual experiences. On the basis of their answers, the men were classified as heterosexual, bisexual or homosexual. The results showed that the maternal aunts, grandmothers and mothers of both bisexual men and homosexuals had more children than those of heterosexual men.

Camperio Ciani emphasises that, rather than being a «gay gene», this unidentified genetic factor is likely to promote sexual attraction to men in both men and women. This would influence a woman’s attitude rather than actually increasing her fertility, making her likely to have more children.

Simon LeVay, a neuroscientist and writer based in West Hollywood, California, describes this as a sort of «hyper-heterosexuality» and explains how it would help to ensure that homosexual behaviour was passed on through the generations. «The positive effect of an X-linked gene on female fecundity tends to outweigh the negative effect of the gene on male fecundity.«