It has been suggested that there is a biological purpose for homosexuality, linked to one for prostitution. And based on all things, a biological purpose for marriage.
Begin with mammalian reproduction. Males want as many females as possible to have offspring with their DNA. Females both want the best male DNA, and among those mammals that raise their young, the best ‘provider’ male to help them raise their young.
But when there are a lot of males around, it is unlikely that the one with the best DNA is also the best provider.
Humans came up with socially enforced marriage because it is a better deal for all concerned. Greater assurance to the man that his children have his DNA, in exchange for monogamy. And females agree to less than perfect male DNA in exchange for greater assurance the male will stay with her to provide for their children. And the benefits to the children of having two parents is obvious.
However, this creates a problem. That being that while only a percentage of adults *should* have children, many more *want* to have children. But biology does not want them to have children. A conflict.
Enter homosexuality and prostitution. In both cases, they provide an outlet for people who should not breed. This is supported by it being much more likely that both homosexuals and prostitutes have many more genetic and congenital problems than do people as a whole.
Genetic problems that would inhibit reproduction even if they were in a monogamous heterosexual relation.
Because in a way, the biological goal is to keep them from interfering with a breeding couple, which would be bad for the species.
‘Humans came up with socially enforced marriage because it is a better deal for all concerned’
Humans did not come up with marriage. God ordained marriage.