Typically we can only say of any heritable trait that it didn't hurt our ancestors too much. I think I mentioned that homosexuality could wax or wain independently of its effect on present-day Homo sapiens but I guess the connection wasn't clear enough. I personally *suspect* that homosexuality is a trait we share with our ancestors that has had a more of a positive, social-bonding effect than a negative effect on absolute production of offspring, but obviously I don't know that. When we're looking at something like homosexuality, we don't really even know what we're looking at. Homosexuality could be a "side-effect" of a hypersexuality which allowed our ancestors to overcome seasonal breeding patterns. It could be a "side-effect" of a strong pair-bonding instinct. It could be a "side-effect" of both of those or yet another physio-sociological phenomenon.
As to the effect anti-reproductive effect, remember that my hypothesis is that homosexuality is probably a *net* positive for species survival. I think it's not unreasonable to suppose that particularly female-female homosexual pair bonding reduces population fecundity. Male-male pair bonding would probably have a smaller effect. It's be no means a safe assumption. Humans have sex a lot more than they need to to reproduce. Still, it's not unreasonable.
But I think it is clear that the social bonding common to our branch of the primate tree helps our survival enormously and sex was probably an important medium of bonding before language had formed. Whatever makes us hyper-sexual, pair-bonding animals (with a tendency for homosexual behavior) almost certainly helped our ancestors to work together and thrive.
Homosexuality and heterosexuality are not equally reproductive and we are, from a population standpoint, obligate heterosexuals (we're not snails or sea anemones). That doesn't mean a significant amount of our population can't do things other than that which will produce babies. It just means we have to be heterosexual enough to build our population. And with 6 billion of us now, that's pretty heterosexual. But of course it doesn't matter how many babies we have, only how many of those babies live to reproduce and our social nature is what provides for our survival.
boddi
On 11/25/05, Miles Jackson <cqmv at pdx.edu> wrote:
> boddi satva wrote:
>
> >
> > I prefer a biological conclusion something like this: homosexuality is
> > prevalent across time and populations. Therefore it must have, or have
> > had, some positive benefit to the societies of ourselves or our
> > ancestors in order to overcome its obvious anti-reproductive effect.
> > It must, therefore, be "natural" in some respect, whether it is the
> > product of genetic, physiological tendencies or social behavior
> > tendencies or both.
>
> One of the most egregious misapplications of evolutionary theory is the
> claim that every discrete, significant trait or behavior pattern in a
> species can be explained by its effects on reproductive success. This
> kind of dogmatic functionalism was rejected by Darwin over 100 years
> ago; he was quick to point out that many factors--not just natural
> selection--can shape physical characteristics and behavioral patterns.
> Evolutionary theory does not require us to make up the kind of "just so"
> story b. paints above; in fact, a thorough understanding of the theory
> discourages us from this kind of "every thing has a positive benefit"
> reasoning.
>
> Thus there really isn't any puzzle here; as with many behavioral
> patterns and traits, homosexual behavior could exist and persist in many
> mammalian species even if it has no positive benefits or no effects on
> reproductive success at all. This may seem counterintuitive, but it's a
> Darwinian point that has been made by evolutionary theorists time and
> time again.
>
> Miles
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