Potential Evolutionary Role for Same-Sex Attraction

[The Straight Story]

Potential Evolutionary Role for Same-Sex Attraction

ScienceDaily (Feb. 4, 2010) — Male homosexuality doesn't make complete sense from an evolutionary point of view. It appears that the trait is heritable, but because homosexual men are much less likely to produce offspring than heterosexual men, shouldn't the genes for this trait have been extinguished long ago? What value could this sexual orientation have, that it has persisted for eons even without any discernible reproductive advantage?

One possible explanation is what evolutionary psychologists call the "kin selection hypothesis." What that means is that homosexuality may convey an indirect benefit by enhancing the survival prospects of close relatives. Specifically, the theory holds that homosexual men might enhance their own genetic prospects by being "helpers in the nest." By acting altruistically toward nieces and nephews, homosexual men would perpetuate the family genes, including some of their own.

Two evolutionary psychologists, Paul Vasey and Doug VanderLaan of the University of Lethbridge, Canada tested this idea for the past several years on the Pacific island of Samoa. They chose Samoa because males who prefer men as sexual partners are widely recognized and accepted there as a distinct gender category -- called fa'afafine -- neither man nor woman. The fa'afafine tend to be effeminate, and exclusively attracted to adult men as sexual partners. This clear demarcation makes it easier to identify a sample for study.

Past research has shown that the fa'afafine are much more altruistically inclined toward their nieces and nephews than either Samoan women or heterosexual men. They are willing to babysit a lot, tutor their nieces and nephews in art and music, and help out financially -- paying for medical care and education and so forth. In a new study, the scientists set out to unravel the psychology of the fa'afafine, to see if their altruism is targeted specifically at kin rather than kids in general.

http://www.sciencedaily.com/releases/2010/02/100204144551.htm

[jkshaw]

1. I read of this theory a couple of decades ago,

and it makes sense. I've been aware for many years myself as I worked in theater groups that, in general, gay men are much easier to talk to, more sensitive and caring than heterosexual men, especially those who haven't yet been "house trained" (as my youngest daughter put it) by marriage.

[Laura902]

2. wow, never heard of that study before, very interesting

Does anyone know how, throughout history what percentage of humans have been homosexual vs. heterosexual? I'd be nice if that number increased among humans to serve as a check on our ridiculous population growth-looking at it strictly from an environmental perspective.

[teenagebambam]

3. Actually, I think there IS a theory floating around

about how homosexuality does make sense as a population control.

[Laura902]

4. Do you know any specifics? just wondering

[The_Commonist]

6. I think there's a homosexual explosion happening now.

There are too many people on the planet.
Nature knows this and is doing something about it.
Humans used to kill off more young men in wars, and that helped control the population.
We've stopped doing that quite so much in the past few generations.
Nature is picking up some of the slack.
I've talked to a number of gay friends about this, and they are totally on board.

[Lydia Leftcoast]

5. That makes sense to me

It's just anecdotal, but I've known of a number of cases where it was the gay son who voluntarily took care of elderly family members, not just parents, but aunts and uncles, too.

[Rhiannon12866]

7. Interesting theory.

And I do know a couple of examples of this, too. I know a gay man, in his 70s now, who is devoted to his nieces and nephews since he has no children of his own which was a disappointment to him. And it is very helpful, since he's the youngest of eight children... :-)

And my grandmother had a dear friend, with four sons, but it was her gay son who lived with her and looked after her. I used to take my grandmother to visit them and he was a great guy whose mother always said how lucky she was to have him. BTW, she was still quite active in her late 90s and lived to 105. O8)

[Behind the Aegis]

8. This makes sense on a number of levels.

I have read a variety of different studies in the late 80's and 90's that suggest there is an evolutionary role for sexual orientation. IMO, given the complexity of sexual orientation, I can see this is a real possibility. Many think we humans are "geared" toward reproduction, at least this is the "official line" of many people, but that isn't quite true. We are geared toward sexual activity. If it were simply for reproduction, it is believed we would have more indicators as to "that time of the month/season" like other animals do. Sexuality is often used as a bonding ritual, used to determine status in the group, and/or recreational. Another feature of sexual attraction to the same of the species also limits reproduction.

I read in one study of a group of birds, I think, may have been mice/rodents, that as population increased, so did same-sex attraction. As population decreased, so did homosexual behavior. In effect, it was a case that environment played a factor in sexual orientation, but not in the way that crazy, gay-hating fundies think. It isn't the "domineering mother/absent father" theory or s/he "played with the wrong toys" theory, but rather as resources became scarce, infant mortality rose, life past adolescence/sexual maturity decreased, and lack of adaptation abound, homosexuality decreased. When those factors changed, then homosexuality increased. If one looks at it from a logical construct, it does make some sense. Of course, there is also the possibility, IMHO, that homosexuality is innate to every species at a certain level and this would be so as a form of population control.

[quaker bill]

9. In general

"kin selection" models of evolution generally require a significant survival / breeding advantage be conferred by the behavior. This advantage has to grow with genetic distance for the math to work. If the advantage is not large, then the genetic cost of not breeding will eventually more or less extinguish the trait. I do not see this level of survival advantage now, but perhaps it existed in the past.