A female friend of mine asked me why I think humans crave monogamy from their partners in romantic relationships. She was interested in whether I thought it was instinctual or purely environmental. So here’s my answer.
The desire for monogamy manifests itself in different ways at different times. For example, early in a relationship, there is an incredibly strong instinct for monogamy in all directions: both partners are focused in on each other like a laser. Typically, when enamored, the chemicals of the brain have you so focused on the other person that it’s hard to feel much real attraction for others. This is when monogamy is easy.
Men and women crave monogamy for different reasons. And to understand the dynamics of monogamy, you’ve got to understand these reasons.
Women crave monogamy because, from a biological resources perspective, it’s expensive for a woman to get pregnant. So if you think historically (pre-contraception) it was in the woman’s interest to make sure she had a guy who was going to stick with her and help her and her child survive. I’ve seen this deeply ingrained behavior manifest itself *almost* universally with the women I’ve been with in a “day-after-sex” form of manipulation – it’s very common (probably instinctual) for the day after response to be a solicitation of more commitment.
I think men crave monogamy for one simple biological reason: to increase the chance of paternity. Since for males, unlike females, paternity is not guaranteed. This is the case for all mammals -> in fact, in most species of mammals, the majority of males never reproduce (studies have shown numbers like only 20-40% in many species)… they serve some other social function while only a few of the higher status males reproduce. If you think about it… it only takes one bull to get 250 cows pregnant. So I think the male desire for monogamy originated as a strategy for increasing his chances of paternity with that particular woman (by keeping the sperm of other men out of her reproductive tract).
So for men, possessiveness derives from a desire to ensure paternity (no sperm but my sperm!). For women, possessiveness derives from a desire for protection and resources (if I’m going to have your baby, then you’re going to help keep us both alive).
Two different instincts which still manifest themselves in a world that’s far different from when they were shaped as biological forces.