Gay birds - an evolutionary advantage?

The most common argument against accepting homosexuality as a social norm is that it is unnatural. Sex is for reproduction the argument goes, and same-sex couples can't reproduce (they can, of course, just not with each other), so it goes against nature. Furthermore, homosexual sex can't produce progeny, therefore it is an evolutionary dead end and must be not only unnatural but a conscious choice.

All of this has now been debunked. Same-sex relationships have been observed in a host of species, including bonobos, dolphins, penguins and fruit flies. The relationships show great variety. Male penguins form long-term sexual bonds. Toads will hop on any other toad that gets within range, regardless of gender. Marine snails all start out male, but when two males copulate, one conveniently changes gender. Male and female bonobos fornicate indiscriminately.

Given that it is universal in nature, the argument that homosexuality is unnatural falls apart. Nor, if fruit flies and penguins are doing it, can we argue that it's a matter of conscious choice. Obviously, evolution has not only allowed for same-sex relationships, it would seem to have a purpose, or purposes, for them.

Scientists are now ferreting out those purposes. They believe, for example, that male bottlenose dolphins engage in same-sex liaisons to facilitate group bonding. In a social species, stronger groups mean stronger individuals. Female Laysan albatrosses (shown above), who may remain pair-bonded for life, co-operatively raise their young, with greater success than heterosexual couples. About a third of Laysan albatrosses couples are female-female, for whom males apparently are of but transient utility.

According to Nathan Bailey, a biologist at the University of California, "Same-sex sexual behaviors are flexibly deployed in a variety of circumstances, for example as alternative reproductive tactics, as co-operative breeding strategies, as facilitators of social bonding or as mediators of intrasexual conflict. Once this flexibility is established, it becomes in and of itself a selective force." Why it evolved in humans is rather more difficult to determine than with albatrosses given the distance that human behaviour has drifted from what might be termed "natural." The mystery is deepened by the presence of our fertile imaginations. Sexually-speaking, are we bonobos, dolphins or fruit flies? I'll leave that question to the biologists.