>
> 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