I have my own theory.
Rather than Man being by nature either polyamorous or monogamous, I imagine him as being polygynous, or in the case of females, polyandrous. That men had an evolutionary desire to spread their seed to as many women as possible, while at the same time, women wanted as many protectors for themselves and their young. Of course, men saw other men as competition for mates, just as females viewed other females as competition.
It goes without saying that you can't have a society that both polygynous and polyandrous, because someone is always on the losing end of it. This will always lead to cheating.
So you have a choice.
You form a polyamorous society, in which men have to accept the reality they don't know if they fathered any children. Or you form a monogamous one, in which they do. I think that latter prevailed because the males of the species need to be certain that they fathered the next generation.
These days I see poly vs mono more in terms of love/lust vs jealousy. If you allow yourself to love others, then by default, you exposed yourself to jealousy. You must then learn to control the jealousy. Alternatively, you can try to prevent any jealousy , but only the expense of giving up multiple partners. However, in this case, you must learn to control the lust.
Last edited by nicothoe; 08-02-2011 at 07:59 PM.