Introduction
All organisms have sexual strategies. Sexual strategies may be competitive, cooperative, or both.They are fundamentally amoral. They have nothing to do with what’s good or kind, but only with what succeeds.
Female Black Widow spiders, for example, sometimes eat the males that approach her. Sometimes they may eat the male after - or even during - copulation. It’s a strategy that succeeds because males will approach regardless of the chance of being eaten - because approaching a female Black Widow is the male’s only chance to reproduce. Male spiders that don’t approach don’t pass on their genes. The meal, on the other hand, may help her produce the hundreds of eggs the female will lay after fertilization.
Lions live in prides. Generally there’s one male lion and several females. The females do the lion’s share of the hunting, but when there’s a kill, the male lion will nevertheless takes the lion’s share of the meal. Because lions live polygamously, there are always male lions without prides. Those lions will seek out and attempt to kill a lion with a pride. If they succeed, they will not only take his place, but kill all the cubs fathered by the previous male. Killing the cubs, in turn, throws the lionesses into heat. They will mate with the new lion, producing cubs that are the genetic offspring of the new male.
Some cuckoo birds lay eggs in the nests of other birds. Those eggs hatch first, and the hatchlings grow quickly, so that they can - and do - displace or kill the genetic offspring of the parent-birds who built the nest and laid the other eggs.
Humans
Humans, of course, are smarter than other animals. But we are nevertheless animals, and our instincts and emotions are formed by the hundreds of thousands and millions of years of evolution that made us what we are today.
Men and women are biologically different from each other. Men, for example, create billions of spermatozoa over the course of their lifetimes. At any given moment, a male human can deliver hundred million of them, more or less on demand. Sperm, in other words, are cheap and easy to create, and each male human carries hundreds of millions of them around, all the time.
Females, on the other hand, produce but one egg a month. More importantly, pregnancy, among humans, carries a higher price than perhaps any other animal. This is because of our outrageously large heads, the comparative smallness of our hips - compared to our four-legged friends - and the extreme prematurity of our offspring, who remain utterly helpless for months, and relatively helpless for years. No other animal produces offspring that require so much help, and consume so many resources, for so many years.
Given our physical weaknesses - we have no claws, or sharp teeth, or tusks or horns; we’re not particularly fast, or strong or good at hiding - it’s perhaps surprising we evolved at all. It was our hands and our brains that allowed us to survive - the same things that make reproduction so hard for us.
Evolution
Today we take out successes for granted: our homes, guns, clothes, vehicles, stores and modern medicine. But those things happened in the blink of an eye, in evolutionary time. Ten thousand years ago, or one hundred thousand, or a million years ago, those things did not exist. We - along with many other hominid species who never made it - lived a precarious existence. Our tools were sticks and rocks, and the difference between finding a meal and being a meal might be the difference between life and death, not only for the hunter or forager, but for his family, tribe, or clan.
We are the descendants of the survivors. And not just the survivors, but those who survived, and reproduced. Our instincts, emotions, and preferences are theirs. We inherited not just their resourcefulness, their determination to survive, and their intelligence, but also their sexual strategies. And when I say sexual strategies, I mean of course, not conscious decisions, but instincts, emotions, and preferences - including especially, attraction.
Anyway, all of that - and thanks for staying with me - is context for what I’m about to say.
Men & Women
Men and women have both different, and dualistic sexual strategies.
That should not be surprising, given the different consequences of sex for men vs. women.
I’ve already mentioned it, but it’s worth emphasizing: pregnancy, in our species, is debilitating. A pregnant woman is both slower and more vulnerable, while needing increasing amounts of resources. After pregnancy, she has a squalling infant, which may drive away prey or attract predators, and who requires resources while providing none. Furthermore, before modern medicine, giving birth was both excruciatingly painful, and sometimes lethal. In the time before writing, a pregnant woman was unlikely to make it on her own. She needed protection and resources from her group - or from someone - if she was going to make it.
So consider the incentives, for a moment. Putting aside religion, customs and morality for a moment, a man has a lot to gain, and little to lose from a sexual encounter. Every sexual encounter is an opportunity to pass on his genes, after all. A woman, on the other hand, has a lot to lose - up to and including her life.
For a man there are two sexual strategies. Let’s call them “A” and “B”. Strategy A is to simply have sex as many times as possible, with as many different women as possible. Strategy B is to mate with one woman exclusively, and to protect and care for her and their children. Strategy A may result in hundreds of offspring. B will result in perhaps a handful.
For women there are also two sexual strategies. Strategy A is to mate with whatever man seems to have the best genetic material - meaning, to have children who will go on to have many children of their own. Strategy B is to select a man who is willing to commit to her, and to commit to providing and protecting her and her children.
Strategy A will result in a greater number of options. After all, the number of men who will have sex with a woman is much greater than the number who will agree to commit to her and her children. A combination strategy might be best: have sex with “A” men, while convincing a “B” man to commit to her and her children.
The analysis doesn’t end there, though. If it did, all men would avoid commitment, and concentrate on mating with as many women as possible. Women, on the other hand, would concentrate on luring the fittest men possible.
The problem is that humans are social animals. We have always lived in groups. And children and pregnancy therefore affect not just the people who created the pregnancy, but the group as a whole. A woman who comes up pregnant, with no man care for her or the child, forces the rest of the group into a difficult situation. They can provide for and protect her, resulting in fewer resources for the rest of the group; or they can abandon her.
Groups, therefore, found ways to discourage sex outside of some kind of committed relationship. This is a good outcome for the group, because ultimately the number of surviving children is the mark of the group’s genetic success, and children survive best when the person obligated to care for them and their mother is the person who is the genetic father. He is the person who is responsible for the children, after all, and is also the person with the greatest genetic incentive to make sure they survive.
And so monogamy was born. Interestingly, though, monogamy was not the best option for men or women. It was the best option for children, and for the tribe.
It was an example of the interests of the group superseding the interests of the individuals within the group. As a result, individuals attempted to escape or cheat the system, when they could.
