Thursday, December 20, 2007

Evolution of sex

I'm looking for answers and I'm going to attempt to use this as a notebook to record my results.
The basis for sexual reproduction is to stay a step ahead of parasites (Red Queen hypothesis). E Coli can reproduce asexually millions of times in a 24 hour period but with no change in the genetic code, reproducing asexually leaves all offspring as copies, vulnerable to infection. We need the differentiation brought with sexual reproduction.

Above a chart, on the left each individual creating 2 offspring sexually. On the right, asexually.

In a recent study, women were given men's shirts to smell and select the one they liked the best. In over 90% of cases the woman chose a man who's immune system was at an intermediate difference from theirs, that is not too similar and not too different, suggesting women pick their mate at a biological standpoint for resilience and ability to fight parasites. This can be seen in the animal kingdom, with male peacocks with better plumage attracting more mates, less attractive plumage may indicate parasites, disease or a low resilience.
From this standpoint, why are there homosexuals, how do they chose their mates? Is it natural selection? As Desmond Morris suggested in an earlier blog of mine, is it because they contribute artistically and have more education? Or is it something else, something not readily apparent? For example the addiction gene does not seem to have a useful function, but addicts have problems distinguishing life changing decisions, for example they know using drugs will kill them and they continue. Addiction genes are very prevalent in societies that have been threatened, such as native Americans and the Irish. It seems these self-destructive genes help foster genetic survival. So what is the answer?
This article is interesting and poses some viable theories:
- homosexual behaviour contributes to same-sex alliances which directly contributed directly to survival
- same sex allies in females creates a more nurturing and stable environment in which to raise children while in males it lowers male aggression

Darwin imagined sex as a relatively straightforward transaction. Males compete for females. Evolutionary success is defined by the quantity of offspring. Thus, any distractions from the business of making babies—distractions like homosexuality, masturbation, etc.—are precious wastes of fluids. You'd think by now, several hundred million years after sex began, nature would have done away with such inefficiencies, and males and females would only act to maximize rates of sexual reproduction. But the opposite has happened.
I question the Darwinian theory, that females pick males for reproduction, males are panting dogs and gays have sex just for fun. There is a primal urge lodged in my brain, is it the urge to reproduce that got messed up along the way or something deeper? As Dr. Roughgarden states: "...most scientists are pretty dismissive about same-sex sexuality in vertebrates. They think these animals are just having fun or practicing. As long as scientists clung to this old dogma, homosexuality would always be this funny anomaly you didn't have to account for."
Patrick Henry states: "Evolution is as big a lie as the 'gay gene' and just as thputoghly debunked." Thanks for that Patrick. This is apparently not an easy question to answer.
I do like this theory:
"One of the major arguments regarding the fitness of homosexuality, at least in vertebrates, seem to revolve around child rearing. Caring for offspring is very expensive per individual caregiver, while yielding tremendous evolutionary benefits to the population, by directly enhancing the fitness of the next generation. Because the cost to the individual is so great, many populations have evolved ways of sharing the costs of raising the offspring, such that the benefits to the population are equalized by general costs to the population. In several social mammals, this is done through wet-nursing by non-pregnant females of related newborn, sometimes even requiring the forced abortion of the litters of subdominant females to produce more wet-nurses (seen in some wolves). Likewise, removing a portion of the population from breeding relieves the breeders of some of these costs either directly by assisting with child rearing, or indirectly by taking over other costly activities (like food collection) so that the parents can spend more resources on their progeny."
I like the idea that gay men are meant to be worker bees, not spending our time fertilizing the queen.
All this pre-supposes homosexuality is genetic, this article has some fantastic arguments for this (discounting Mr. Morris, hah!)
1. Homosexuality doesn't prevent reproduction: Of 262 self-identified lesbian women, 75% had had sex with men since age 18 and 43% of those who had always identified themselves as lesbian had done so, according to Kinsey. (no my book hasn't arrived yet)
2. Perpetuity of deleterious genes: Being maladaptive to reproduction does not ensure that a genetic trait will disappear. Even fatal diseases are not eliminated from the human gene pool.
3. Twin studies: Identical twins raised apart, for instance, are more likely to both be homosexual as adults (if one is homosexual) than fraternal twins, and both are more likely to share sexual orientation than genetically unrelated siblings raised together. Some twin studies have shown concordance rates as high as 100%.
4. An unchosen preference: There is no evidence to suggest that the sexuality of the majority of people, homosexual or heterosexual, is a result of a conscious choice on their part. The overwhelming majority of homosexual males and females indicate they never chose to become homosexual, but that they are that way innately.
This may be the best chart I've ever seen:

This was not referenced, indicating the author asked 3 of his friends to collect the data. I love the fact that it mentions welfare mothers, that the percentage of people who support Bush is over 250%, that nobody with a high IQ is gay and everyone who believes in evolution is dumb (also over 150%).
There seems to be no answer, so I'm going to post some other excellence before I go to sleep:
Goku: "we're not hear to judge anyone, but to set an example. i'm all too quick to judge, and it is sin on my part. i think jesus said it best, let he how is without sin cast the first stone.

god made adom and eve, not adom and steve.

people chose to be gay, god did give us choice. animals do not have choice.
there is no rappist gene
there is no killer gene
there is no evolutionist gene
there is no gay gene.

have you ever saw gattaca, the movie? if not watch it some time"
I love the spelling mistakes, the reference to a popcorn movie on a scientific forum, I think he discredits himself better than I ever could.
Mr Potato Head: "So what purpose could they have served? Who knows, maybe they were created by God to be tools for ancient man. Maybe not. Maybe they were easy to part with as sacrifices. Maybe not."
Biochemist: "It is perfectly reasonable to reject gay behavior (for moral reasons or otherwise) and still accept gays as peers, co-workers, employees, friends and citizens. This is not hypocritical, it is normal mature behavior."
Happeh: "Homosexuality is usually caused by an energy imbalance or physical damage to the body. It is not genetic except in perhaps a small percentage of all homosexuals. I looked thru some of the other replies. I do not believe it is population control or anything of the other ideas mentioned.
A person can be turned gay. Any person who masturbates excessively stands a very high likelihood of going gay at some future time. This points to gay being caused by physical changes within the body. Not psychological or genetic factors. "
All these quotes found on science forums. I don't think the world is yet ready to answer the question.

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