Click here for part I of Multiple Long Term Relationships MLTRs and Polygamy
Why Men more than women?
When polygamous marriages occurred in pre-modern societies, they were more likely to involve polygyny (one husband, multiple wives) as opposed to polyandry (one wife, multiple husbands). Overall, of the 1,231 cultures in the Ethnographic Atlas Codebook, 84.6% are classified as polygynous, 15.1% as monogamous, and 0.3% as polyandrous. Polygyny is much more common than polyandry because based on evolution, the benefits of polygyny for men were much higher than the benefits of polyandry for women. On a reproduction point of view, men benefited much more than women did from having more than one partner, and so they were, and are still, rather psychologically adapted to look for new mates.
On that same line of thought, the evolutionary costs of polyandry for men are much higher than the costs of polygyny for women. If you are a man whose co-husband has impregnated your shared wife, then you have to wait at least nine months of gestation, and probably years of lactation as well, before you could get another shot at reproduction. But if you are a woman whose co-wife has been impregnated by your shared husband, you can still get pregnant right away.
You’ll have to share your husband’s parental investment with your co-wife, but at least you’ll be able to reproduce. And being the co-wife of a wealthy, high status, highly desirable man may very well be a better option for you than being the only wife of a less impressive husband which might diminish your and your offspring’s chances of survival. Although some Westerners will wonder why any woman would choose to marry polygynously rather than monogamously, many women cross-culturally still choose to do so.
In line with this cross-cultural evidence, the kind of marriage system that emanates most directly from evolved human mating psychology seems to be obvious. That system is polygyny. Most of our male ancestors seek polygyny, even though only a few could achieve it, while many ancestral women perceived that their own interest would be better served as the co-wife of a really impressive man, like the tribal leader, as opposed to being the sole wife of a less impressive one. As was mentioned before, the contemporary human mind is made of genetically encoded psychological adaptations for mating behavior that evolved in these ancient polygynous environments. That’s why there is so much de facto polygyny in our Western culture, despite the West’s attempts to get rid of it in favor of a marriage system that biologist Richard Alexander refers to as “socially imposed monogamy.”
So the natural question coming from this is: If polygyny is so “natural” for humans, why did the West end up proscribing it and prescribing monogamy?
The evolution and spread of monogamy
Again, if our ancestors’ environments were so polygynous, why is “socially imposed” monogamy, the moral and legal prohibition of polygyny, so common in modern societies? Or more accurately, why is it so common in the West? Polygyny remains legal and common in many societies, especially African and Islamic countries.
Monogamy’s spread had something to do with the influence of Christianity, but not as much as we would like to think. Conventional Christianity has always enforced monogamy, but Christianity’s condemnation of polygyny has never been as straightforward as anti-polygyny. There are no Biblical passages that explicitly prohibit plural marriage. In fact, several central Old Testament figures were polygynists. Abraham, for instance, had two wives simultaneously, and Solomon had 700 (plus 300 concubines).
But, why did it spread? A plausible answer is because in history, monogamous groups were advantaged militarily over polygynous groups. The ancient medieval European leaders who were in favor of anti-polygyny laws were highly involved in the business of war. Their own social status and survival often depended on their ability to keep large, well-funded armies. The imposition of monogamy produced bigger, better armies, because monogamous groups can grow larger than polygynous ones. Men want wives, and if you need a lot of men on your team, you must offer them something that they want.
In monogamous groups, high status males cannot accumulate large numbers of women for themselves. The more equal distribution of women in monogamous groups means that more men can have wives, and fewer men have to leave the group to search for wives somewhere else. The larger the group, the more men there are to fight in battles and to pay taxes for the funding of wars. Socially imposed monogamy, therefore, emerged in the West as an arrangement in which elite males allowed lower-ranking males to marry, in exchange for their military service and tax contributions.
After socially imposed monogamy was established, Westerners became so accustomed to it that it became the normal state of human mating, and the formerly universal practice of polygyny was seen as foreign and strange.
Cost of reproduction as a factor
So it’s true, men are on average more interested than women in acquiring new sex partners. Evolutionary success is mainly about success in reproductive competition, and how one achieves this success depends on how much one has to invest in the production of offspring. This parental investment can take many forms, including the investment of one’s own bodily reproductive capacity.
In general, female mammals must make a large basic investment in order to reproduce, like nine months of gestation and years of lactation, whereas male mammals can reproduce with a much smaller minimum investment. This does not mean that males don’t benefit their offspring in essential ways by investing beyond this bare minimum. However, it does mean that because the obligatory costs of reproduction are much lower for males than for females, there are significant differences in the mating strategies that males and females evolve.
The typical pattern, and the one that applies to humans, is that females evolved to be relatively choosy about who they mate with, and relatively low in “sociosexuality” (relatively uninterested in promiscuous, uncommitted sex). Males, on the other hand, have more to gain and less to lose from having large numbers of sexual partners, and they evolve to be less choosy and higher in sociosexuality.
What does this mean for today’s men?
This sex difference in the desire for new mates doesn’t mean that men aren’t interested in long-term, committed sexual relationships; on the contrary, most men strive for such relationships and value them deeply. But it does mean that even when he is involved in such a relationship, the average man will see opportunities to mate with new partners as being more compelling than would the average woman. Also, the strength of this temptation will generally be proportional to his social status, because the higher his status, the more women will be attracted to him (again, for basic evolutionary reasons), and the more opportunities he will have.
So the high status man will often face a dilemma. While some evolved modules in his brain, his “long-term interest” modules, are coaching him to act in ways that will benefit his family, career and reputation, other evolved modules, his “mating” modules, are urging him to pursue new sexual opportunities, because his genes don’t want to be weeded out of existence. And these mating modules, besides being unrelentingly persuasive in their own way, may even actively sabotage the influence of the long-term interest modules, by causing the man to underestimate and discount the risks involved (his family, his career and reputation), in the pursuit of sexual thrills. Thus the man may be compelled to pursue these thrills in ways that, to other people, seem surprisingly irresponsible and stupid. “Why on earth would he think he’d be able to get away with that?”
So we have seen that the genetically encoded psychological machinery of human mating behavior was built by, and for, a world in which striving for polygyny was often reproductively advantageous. That’s why people living in modern societies often seem inclined towards polygyny, even in cultures that have attempted to abolish it. It explains why more than half of weddings fail, and why “high-status” celebrities relationship scandals are so prominent.
I believe that if a man wants to avoid wrecking his life for the sake of pursuing new mating opportunities, his best hope is to recognize that when these opportunities present themselves, his brain’s mating modules will know precisely what they want him to do, and he may feel like they’re making a heroic effort to get him to do it. They may even cause him to badly underestimate the damage that his actions could cause to his family and career, and to overestimate his chances of getting away with it or of being forgiven. To avoid doing something they may regret, it’s important that men recognize their mating modules for what they are, and be aware of what they’re trying to persuade them to do. This knowledge will increase their power to ignore them, and to listen more to the parts of their brain that evolved to serve them in the long term. This knowledge will be achieved by living more consciously.
So the answer is clear, I am more susceptible than my girlfriend to want to cheat. But as long as I hold on to my long-term goals, the ones that led me to be in a relationship in the first place; such has having, one day, a healthy family with two parents that actually love one another, I should be able to control the subconscious urges that could lead me the other way. Monogamy is a breeding behavior that is considered to give offspring a better survival chances, as in monogamous couples females receive all the support of the male in raising newborns to adulthood, from food to protection. It’s clear: a pair achieves more food and survives better than the bachelors. And even though we don’t have to worry so much about survival today, I am convinced that monogamy is what humans should strive for.