Nate and I had brunch with one of my (straight) work mates on Saturday. He had gone out the night before with two of his other gay friends (a married couple) and was slightly disillusioned when he found out that this couple had an open relationship. I must admit that I was a little surprised also; Nate, less so. This got me thinking...why are humans monogamous and is there a difference between straight and gay couples?
Monogamy is quite rare in nature. In fact, thanks to DNA finger printing, we are beginning to realise that many so called 'monogamous' species partake in sneaking extra pair copulations on the side.
In some animals, like seahorses, pairs remain monogamous because the cost of partner switching is quite high.
Some evolutionary psychologists suggest that our monogamous mating system is quite recent and that our evolutionary ancestors were promiscuous. Compared to other great apes, the size of our testes and penises are large for a species with a monogamous mating system.
Sexual conflict is rife throughout the animal kingdom as each sex tries to maximise it's own reproductive success. Here, it is not uncommon for each sex to wish monogamy on its mating partner whilst engaging in promiscuity for themselves.
So...I wonder if open relationships are more common in same-sex relationships because there is less of a sexual conflict.