According to the study, polyandry might have traditionally been a way in which families consolidated and maintained plots of land among the male's family (the co-husbands were usually brothers who took an outside bride). Over time, these relationships became less of a contract and more romantic. The implication of this essay indicates that women are socially built to take multiple partners. We can further see this in numerous cultures that broaden the definition of what it means to be part of a non-traditional family.
After I told my friend about this research, I paused. He leaned back, clearly thinking about what I’d just said.
“Well that type of relationship seems justified in that there’s a ‘contractual’ reason for their relationship. Also, it can’t be proven that this relationship became ‘romantic’ because men have a tendency to be territorial. A man isn’t going to just sit by and let another man take his woman.”
I pondered this for a second
“The issue with that is that there are numerous cultures where women have sex with multiple men and the men take care of the child.”
The look on his face was priceless. This seemed to give him pause.
There’s no greater example of this than in certain parts of the Amazon, where it’s also not uncommon for women to take multiple lovers. According to Amazonian customs, when a woman bears a child with any of her lovers, all the men involved are considered the biological fathers, whether they actually fathered the child or not. This helps maintain a community culture where each of the men were considered part of the family unit and helped nurture and protect the family. As it stands, if you don’t know who the biological father is, it’s safer to take care of the child just in case it happens to be yours. In this way, the woman’s sexual relationships with multiple men functions as a deterrent and actually encourages both men AND women "nest," taking care of the child as a community.
“Alright, that’s fine. There are always exceptions to the rule. What I’m saying is, across the board this isn’t the case. Men and women cheat at about the same rate, right? Can we at least agree to the fact that women just aren’t set up like that? Like, they aren’t biologically built to take more than one partner.”
He looked at me when I didn’t immediately answer.
As it turns out, women’s tendency to wander (and its consequences) might be rooted in evolution.
Read: The 4 Things I've Learned Since I Started Swinging
In their book “Female Infidelity and Paternal Uncertainty”, Steven Platek and Todd K. Shackelford talk about "sperm wars" in men and women and how women might be hardwired to seek out multiple partners in prehistory. They researched multiple instances of insemination in ancestral women. They state:
“Facultative polyandry (female sexual infidelity) would have been the most common reason for the simultaneous presence of live sperm from two or more men in the reproductive tract of an ancestral woman.”
In other words, we’ve been doing this for a long time, to the point where men became threatened because of our promiscuity. This might have helped create the social structure of monogamy. They suggest the reason for modern man's persecution of women who cheat/seek out multiple sexual partners might be rooted in something called "sexual jealousy."
Sexual jealousy is a mechanism that maintains monogamy. For men, that means that their sperm "wins" the sperm war due to lack of competition. This effectively makes it so that their genes stay in the gene pool, making it more than likely that his genes will fertilize the woman without having to compete with other men whose sperm would otherwise be present in her reproductive tract.
Read: 8 Ways Polyamory Helped Shape My Monogamous Relationship
However, Platek and Shakleford make an interesting point: sexual jealousy wouldn’t have developed unless women didn’t practice monogamy to begin with.
The research implies that it’s a completely natural, ancestral tendency of women to seek partners outside of their monogamous pairing. However, this urge is suppressed by society - just barely - and they cheat just as much as men. It could be argued that woman’s polygamous instinct caused society to evolve toward monogamy, especially for women whose sexual liberation threatened male genetic continuance. Women who go against the grain are punished or looked down upon, while women who stay at home are rewarded.
In short, while the West holds certain ideas about men’s propensity to engage in infidelity and women’s tendency to "stay at home and nest," recent research is beginning to turn this misconception on its head. Instead, we’re beginning to find evidence that not only shows that men and women cheat in equal measure, but that there are also evolutionary reasons why women may engage in relationships with multiple men outside of their monogamous relationships.
All in all, I think this sheds light on the breadth and depth of cheating in relationships. If we know the why and how of cheating maybe we can explore other options in our relationships or at least be more forgiving. I think my friend and I left that conversation with new ideas about how relationships work.