Same-Sex Behaviour Evolved in Many Mammals to Reduce Conflict, Study Suggests

Same-sex sexual behaviour probably evolved independently several times in mammals as a way to smooth out social relationships when they started living in groups. An analysis of more than 6,000 mammalian species found that about 4% exhibited same-sex behaviours — including courtship, mating and forming long-term bonds — and these were particularly prevalent in non-human primate species. The researchers caution that the findings can’t explain the evolution of sexual orientation in humans.

Blogger Comments:

Firstly, evolution doesn't happen 'in order to' (purpose); it happens 'because' (reason).

Secondly, the only thing that survives from generation to generation is genes, and genes are passed on through heterosexual behaviour, not homosexual behaviour, so homosexual behaviour does not 'evolve' in species through natural selection. 

Instead, homosexual orientation can be explained developmentally through chromosomal crossover, or at least, some process of genetic recombination. That is, if a child inherits genes that probabilise sexual attraction from its opposite sex parent, then attraction to its same sex will be probabilised, as when a male inherits from the female, and the female from the male.