The 'is' and 'ought' of homosexuality

On Friday I wrote about David Torkington's piece in 'The Catholic Universe' describing, in his view, the homosexual colonisation of the Catholic Church. "The elephant in the room that threatens to bring our Church to its knees" also featured his searing theological attack on sodomy.

Yesterday (Monday) I posted "The evolutionary genetics of homosexuality (GWAS)" which described the work of a large team headed by Brendan Zietsch showing that homosexuality had strong genetic correlates and was associated with greater reproductive fitness in near relatives.

I'd like to draw your attention to a third post I wrote back in October 2014, "Evolutionary roots of homophobia" where I quoted The Economist: "Revulsion against homosexuals is ancient, deep and, in its way, sincere."

The angst is always about male homosexuality.

That there are good evolutionary explanations for a trait is a fact with limited consequences. Psychopathy is also strongly heritable and appears to be under genetic control. It's generally accepted that psychopaths 'can't help it'. That does not make their behaviour acceptable: negative externalities.

My conclusion in the 2014 post was this:

The reason for an evolved heterosexual disgust towards homosexuals (mislabelled as 'homophobia') is that in the environment of evolutionary adaptedness (EEA) homosexuals were more likely to be disease vectors.

This due to the unsanitary nature of some male homosexual sex acts.

In the first world today:  modern hygiene. Our emotions are still there of course, locked in our survivalist genome. The suppression of disgust in the name of compassion - where we know we will pay no real price - is called tolerance.

Psychopaths shouldn't be tolerated; homosexuals in our modern societies should be. Few non-homosexuals, however, feel an inner instinct to celebrate it. If you think you do, view some of the more controversial gay photographs by Robert Mapplethorpe and gauge your reactions.

The evolutionary genetics of homosexuality (GWAS)

Tom Whipple, science editor at The Times, has this piece today.

Sexuality genes linked to sex appeal

The genes that make some people gay could also help straight people to have more sex, according to a study that may help to explain the evolutionary paradox of homosexuality.

Although there is no “gay gene”, scientists have long known that there is a strong genetic component to homosexuality. This leads to a conundrum: given that gay people have fewer children, the genes linked to homosexuality might be expected to be less likely to survive.

A leading theory of why this does not happen has now received its clearest validation. US scientists scoured the genomes of 400,000 people and compared their DNA to surveys about their sex lives. They identified a whole suite of genetic variants associated with people having had a same-sex partner.

They also looked at the sex lives of those who had those genes but who had never slept with someone of the same sex — and found an intriguing result.

According to the results, presented by an international team of researchers to the Human Behaviour and Evolution Society, straight people with the gay genetic variants had more sexual partners and were seen as more attractive. This fits with the “gay genes hypothesis”: that the genes that make some people gay persist in the population because they have reproductively beneficial effects in others.

It's been clear for a while (see lead author Brendan Zietsch's paper from 2008) that female relatives of gay men (such as their sisters) tended to have more children than the female relatives of men with fewer gay characteristics, and that heterosexual men with more alleles for feminised traits were also more reproductively successful. This has been called the Johnny Depp effect. The novelty here is the size of the sample, 400,000, and the use of genomic data.

Whipple did not give a reference and it took me a little while to track down the actual paper, from here.

HUMAN BEHAVIOR AND EVOLUTION SOCIETY
30th Annual Meeting
July 4th – July 7th, 2018

The evolutionary genetics of homosexuality

Brendan Zietsch, Andrea Ganna, Karin Verweij, Felix Day, Michel Nivard, Robert Maier, Robbee Wedow, Abdel Abdellaoui, Benjamin Neale, John Perry

Homosexual behaviour in humans is genetically influenced and is associated with having fewer offspring. This presents a Darwinian paradox: why have genes that predispose to homosexual behaviour been maintained in the population despite apparent selection against them?

Here we show that genes associated with homosexual behaviour are, in heterosexuals, associated with greater mating success. In in a genotyped sample of more than 400,000 individuals from the UK and USA, we for the first time found genome wide-significant association of specific variants with ever having had a same-sex partner, and hundreds of additional variants were significantly associated in aggregate.

Among men and women who had never had a same-sex partner, these same aggregate genetic effects were significantly associated with having more lifetime sexual partners and, in an independent sample, with being judged more physically attractive. Our results suggest that genes that predispose to homosexual behaviour may have been evolutionarily maintained in the population because they confer a mating advantage to heterosexual carriers.

The paper is gated of course, and I haven't been able to find an open-access version. But you get the idea. I suspect we're well down the road to putting Gregory Cochran's 'gay germ' theory to rest.

Gay; Asperger's syndrome; football

Here's a thesis. Being gay and being an "Aspie"  are both under the control of a large number of alleles of small effect.

In the 'gay'  case, less means a sympathetic, empathic personality; in the Aspie case,  less means a focused, dispassionate and logical intellect.

In both cases the full deck decreases reproductive success while a partial hand can enhance it.

Perhaps Asperger's syndrome is the gentile equivalent of Tay-Sachs disease and similar neurological collateral damage found in Ashkenazi Jews under selection for systemic, analytical intelligence in the mediaeval middle classes.

World Cup: England loses to Uruguay. The English looked hard-working, stolid and flat-footed ; the South Americans  (of Mediterranean lineage)  were dynamic and explosive. What do you think, agrarian farmers  vs  pastoralists?

Once you get your eye in, genes are everywhere!

The diplomacy theory of male homosexuality

Since male homosexuals, by definition, leave fewer offspring than male heterosexuals, the genetic basis for ‘gayness’ should rapidly be eliminated from any breeding population. Since the incidence of male homosexuality nevertheless seems stable and significant, around 5%, there appears to be some kind of paradox here.

It has been suggested that gay men make better uncles than straight men, thereby facilitating straightforward kin selection. But there is little evidence for this. So here is my proposal.

1. Gay men tend to exhibit more relational competences than straight men. Evidence: the prevalence of gay men in service professions; the discussions about the ‘feminised brain’ of male homosexuals.

2. In the environment of evolutionary adaptiveness (EEA), the foundational basis of group dominance in primate species, including man, is typically aggression. This comes down to the leader’s ability to physically dominate others by violence and intimidation.

3. Leadership by the physically most intimidating is counter-productive where intelligence is at a premium, as in human evolution. The ‘wisdom of crowds’ applies. There is a requirement to negotiate points of view, insights and buy-in across the group.

4. Gay men bring particular interpersonal skills to group problem-solving and group cohesion. Groups with such functions out-perform groups which operate only on a hierarchy of fear, where the powerful leader cannot be contradicted. Note that due to the sexual division of labour, women cannot perform these functions.

5. Since all competing human groups in the EEA were extended kin groups, genes for male homosexuality had some use after all and so were conserved.

In fact, in today’s more complex societies exactly the same points apply.

Experimentally testing this idea would involve comparing problem-solving competences (in novel environments) for stable groups contrasted in temperament as typically found along the straight-gay axis. The prediction would be that maximal effectiveness would be exhibited by groups in the straight-gay ratio of around 19:1. An alternative would be ethnographic analysis of groups looking at roles played by gay men.

Notes

1. Due again to the sexual division of labour, it seems this analysis is not at all applicable to female homosexuality.

2. A possible difficulty with this suggestion is that there are plenty of men around who seem adept at diplomatic skills without being gay. The term 'metrosexual' seems to have been coined for this group! However, perhaps there is a continuum effect, and gay men are simply the most effective in these kinds of roles, sufficient to offset their lack of direct 'fitness'.