Via Paul Hsieh (whose Geek Press I recommend reading daily, because it doesn't take long--he only posts a few quality topics each day, and he always comes up with neat stuff), there's an interesting article in the New Scientist about some recent developments in simulated evolution, in which artificial organisms develop capabilities based on mutations that would be seemingly unrelated to them.

Evidence of a gradual biological evolutionary process is found in complex structures that retain features related to earlier evolutionary steps. The human eye, for example, contains crystalline proteins that are related to those that perform enzymatic functions unrelated to vision.

The researchers say their computer model will let biologists study individual evolutionary steps for the first time. "Darwinian evolution affects DNA and computer code in much the same way," says Christoph Adami, who leads the Digital Life Laboratory at the California Institute of Technology. "This allows us to study evolution in this electronic medium."

Lenski adds that some mutations, which initially looked as if they would not be advantageous to an organism, turned out to be crucial stepping stones in the long run.

This is one response to the argument made by some that homosexuality can't be genetic, because "the gene would die out." This is reflective of an overly simplistic misunderstanding of genetic evolution. If homosexuality is purely genetic (and I won't be surprised if it is) as opposed to womb environment or some combination of the two (it's quite clear to me that homosexuals are born, not made), I'l be very surprised if it turns out to be a single gene. More likely it will be found to be a complex of genes, each of which has some non-sexual evolutionary utility, but in combination confer the unfortunate (at least in our present society) trait of inability to feel a physical attraction for the opposite sex.

A similar example is the gene for malaria resistance, very useful to people living in the tropics, but of which a double dose (from both parents) results in the deadly disease of sickle-cell anemia. In temperate climates, there's no benefit to the gene at all, and it may eventually disappear in the African-American population, but it will take many generations.

Like Autism I can think of evolutionary reasons for homosexuality to occur. There have been interesting studies I've been cited (but can't find at the moment) concerning this subject.

One theory is that it's advantageous in endogamic tribal societies because it promotes "uncles" and "aunts" who contribute to the success of offspring. If your tribe is limited by the carrying capacity of the local area, then selecting for improved quality of offspring vs. more may be the better strategy. While a homosexual wouldn't reproduce directly, there would be a strong genetic relationship with most (if not all) of the children in the tribe. So if this promotes the longevity _of the tribe_ it could well be selected for.

If I recall correctly, animal studies appear to indicate that there's a fairly strong correlation between population density and the percentage of a population that are homosexual. My anthropology class was some time ago, but I believe that these results was strong across species, including primates. If so, it would appear that there's a built in safety valve to population pressure. This of course only applies to the general population numbers as a whole, but, combined with the studies that suggest that "sexuality" is a continuum, I would imagine that all of us contain some combination of genetic triggers which would lead to homosexuality in greater percentages of the population subject to different population pressures. The interesting thing about the theory is that it's quite simple compared to trying to identify how any given percentage of homosexuals within a population group would be selected for. Identifying post facto a specific evolutionary pressure that chooses for behavior is probably shooting in the dark.

Spilled seed, is the way I see it. How far off base has real science gone! Evolutionary pressure on a population leads to homosexuality? How about a behavioral response based on bad family relationships during childhood? Or broken homes, or pederasty, or just a learned behavior? Sounds like a modern myth to support a social agenda. If there was a genetic link , it would have to be based on the Y chromosome, you don't get any response from nature due to males spilling there sperm.

Rand, for once, I think you're buying into a demonstrably false liberal myth. Why is it so hard for people to acknowledge that homosexuality, like all other behaviors, is BOTH genetic and learned. Proof of this are identical twin studies. As I recall, somewhere in around 50-60% of the cases where there is at least one homosexual, the other is too. That leaves 40-50% of cases where genetically identical humans have opposite sexual orientations.

I do recall where gay/bisexual geese are quite successful raising the offspring of their common female spouse.