On The Nature and Variety of Human Sexuality

Many interesting thoughts and insights in this article.

A few quotes:

For women, pregnancy is a difficult, costly process, and raising children even more so, meaning that sex must be taken seriously. By and large, biology conditions women to avoid casual sex and to connect sex with love. It also pushes them to look for good providers who tend to be older and wealthier.

Men, on the other hand, have lots of love to give at no cost to themselves, and they behave in ways that will spread their genes as widely as possible. On this theory, men will settle down with a woman who is fertile and whose fidelity is assured, in order to have legitimate offspring. But they will also sleep around as much as they can, especially with women who possess the key ‘fertility cues’ of youth and physical beauty.

Someone who reads only the media coverage might wonder why anyone takes the evolutionary study of sex (ESS) seriously. It is easy to caricature, and many of its followers seem intent on doing the job themselves. In the past couple of years, evolutionary psychologists have been able to grab reporters’ attention by suggesting, for instance, that men with smaller testicles make better fathers, that men with attractive partners perform oral sex more often because they’re checking for competitors’ sperm, and that women have orgasms in order to attract mates willing to commit to raising offspring.

Though the data from Buss’s surveys confirmed the basic hypotheses of Trivers and Symons, the resulting theory introduced some important refinements. Notably, sexual strategies theory pays attention to an obvious fact that earlier evolutionary psychologists had left largely unanalysed: women sometimes want casual flings, too. According to sexual strategies theory, women don’t altogether avoid sex outside of committed relationships, but they use different criteria for choosing partners depending on whether they are engaged in short-term or long-term mating. Women out for casual sex generally place a premium on looks, which signal fertility and genetic health, in contrast to those looking for a long-term partner, who look for someone with status, maturity, and access to resources. There is nothing maladaptive about a woman having a casual affair. It’s a great way to get access to strong, healthy genes, and ones that are different from those of her other children, thereby increasing the family’s overall resistance to disease. She just has to be sly about it, so she can still hold on to her life partner.

Two US anthropologists, Katherine Starkweather and Raymond Hames, have recently shown that polyandry, the practice of women taking multiple husbands, is much more common than people in their discipline previously recognised. And Stephen Beckerman at Pennsylvania State University has drawn attention to what he calls ‘partible paternity’, where a woman has sex with more than one man in order to get pregnant, with these multiple partners jointly recognised as fathers of the offspring. This practice is common throughout the lowlands of South America, and other examples can be found around the world. And some cultures, such as the Na (or Mosuo) people in southwest China, don’t seem to have any stable pair bonds at all. Among the Na, monogamy is frowned upon, everyone is free to have as much casual sex as he or she wants, and jealousy is apparently unheard of.

Even if evolutionary psychologists come up with the perfect theory to link our sexual behaviour to the hardwiring in our brain, many people would argue that it wouldn’t matter much anyway. We would still wake up every morning to be buffeted by desire’s mysterious winds, and we would still be left to cobble together, from our unruly urges and our imperfect decisions, lives that make as much sense to us as possible. Tracing your sexual preferences back to the Pleistocene doesn’t help you decide between the rough boy in the leather jacket and the nice banker who will help with the kids. And yet, when all is said and done, we’re animals – and evolution is the most powerful tool we have for understanding the animal world. Biologists would not try to explain the development of our kidneys or our immune systems without reference to human evolution. And it would be very odd if evolutionary theory had nothing to contribute to the understanding of the human mind.

So we all have an interest in figuring out what will make us sexually happy. Humans in the 21st century, at least those in developed, Western democracies, live in an environment that provides almost complete sexual liberty. And thanks to technology, we can now connect with one another with unprecedented ease. We can see more potential mates in an hour on Tinder than our Pliocene ancestors encountered in their lifetimes. Assuming that we are hard-wired sexually, ignoring that hardwiring will come at a cost. Modern consumers have unlimited freedom when it comes to food. But if they use that freedom the wrong way, they could make themselves obese, and potentially die of a heart attack.

Though evolutionary psychology is often seen as a conservative discipline, dedicated to providing justifications of the status quo, its final conclusions could be quite radical indeed. Researchers might tell us that it’s the accepted norms of our culture that are doing violence to our nature. Indeed, the current best-seller among ESS books, Sex at Dawn (2010) by Christopher Ryan and Cacilda Jethá, two self-described ‘shame exorcists’, is a sustained attack on our society’s norm of monogamy. It surveys the anthropological record, as well as the behaviour of our closest primate cousins, chimpanzees and bonobos, and makes the case that humans actually evolved to be promiscuous. Ryan and Jethá claim that it is only with the advent of modern agriculture, and men’s ensuing need to protect their inheritance, that humans began to expect exclusivity from their partners. They attribute our modern sexual malaise to the mismatch between our Paleolithic libidos and the monogamous straitjacket into which we have forced ourselves.

If jealousy is truly hard-wired, as sexual strategy theorists claim, then experiments with non-monogamy and what Savage calls ‘monogamishness’ are perhaps doomed to fail. But if jealousy is instead the product of a contingent set of historical circumstances, it might be that our norms need to go.

And one more article on notions of everlasting love.