Evolution and Sexual Behavior

Science goes through fads like anything else. Every now and then, it becomes fashionable to describe phenomena with one theoretical framework. At the moment, it’s en vogue to interpret human behavior and sexuality in terms of evolutionary psychology.

“Men are hardwired to spread their seed to as many women as possible.”
“Women are programmed to seek the alpha male of any group, regardless of commitment from other men.”
“Men are evolutionarily designed to be dominant.”
“Women are hypergamous by nature.”
“Humans are meant to be polyamorist by nature.”
“Women are innately attracted to size and strength.”
Etc.

Newspapers, magazines, journals, dating advice websites and blogs are rife with language like this. Some draw reasonable conclusions. Others draw some pretty drastic and ghastly ones. The implications is the same across all of them: human sexual behavior is preordained, and men or women who deviate from it are either psychologically dysfunctional or are denying their instincts for the sake of power and dominance.

In Medieval times, the Catholic church decreed a version of human nature which was unwavering and unscientific. Sex was only permitted between a man and a woman who were married before God, in missionary position, and only for the sake of procreating. There was no evidence or falsifiable hypothesis to this, it was simply intuited by the intellectual elite at the time and passed down as fact through the population.

Strangely, something similar seems to be happening with evolutionary psychology and its interpretation of sex and human nature. Not that evolutionary psychology doesn’t have some truth to it, and not to say it’s not more correct than the Catholic Church’s version — it does have some truth to it and it is more correct. But its hypotheses are not falsifiable (and some argue, therefore not scientific) and many of its conclusions are merely intuited, not actually tested.

The goal of this piece is not to argue that evolution is wrong or that it’s a poor explanation for sexual behavior. On the contrary, I believe it’s the best one we have at the moment. The goal of this piece is to show that most non-scientists who speak about evolutionary psychology and its implications on sexual behavior have absolutely no idea what they’re talking about and should be listened to a with a healthy amount of skepticism.

I’ll begin with a short explanation of genetics, so everyone’s on the same page. I’ll then get into the major categories of errors you see: genotypes versus phenotypes, evolutionary stable strategies, and distributions across populations.

If this sounds about as exciting as prying shards of glass under your fingernails, then I assure you, I’ll keep it as interesting and light as possible. Last thing I want this blog to become is an academic bore. But I strongly believe this is an important topic, particularly for smarter men and women who have found themselves leaning on statements similar to the ones above to justify their actions or beliefs.

Genetics for Dummies

I’m not going to bore you with the Biology 101 version of genetics. If you want a more detailed explanation, I recommend Wikipedia’s thorough introduction to the subject.

We all have DNA. DNA is made up of thousands of nucleotides. These pairs of nucleotides are called genes and they are the blueprint for our bodies. Our bodies — our height, eye color, hair color, skin color, etc. — are determined by our genes. These are called traits. When we make sexy time with somebody, we shuffle and recombine our genes together, which then produce a new human being. This is called an accident, and often ends in child support payments. This new human spawn will then share a combination of traits of both of its parents. Daddy has green eyes, so little Timmy does well. Mommy has webbed feet, so does Timmy.

Some traits are better than others at surviving or replicating. Therefore these traits will tend to procreate more often and become more common in the gene pool. Other traits are worse at surviving or replicating (such as sickle cell anemia), and therefore will be less likely to procreate and sometimes weeded out of the gene pool altogether. This process is referred to as natural selection. Over millions of years, entire species evolve and adapt, change and grow through the process of natural selection. Genes which create traits which are poor at survival eventually go extinct, while genes which create advantages to survival and replication continue on and dominate the next generations of species.

Eventually, someone took the idea of natural selection and began applying it backwards. They said: “Well if humans are already like X, then that must mean that X is a genetically advantageous trait or behavior.” They then try to explain why this trait or behavior is advantageous to survival over the alternatives. A simple example is an innate fear of snakes and spiders. Recent research suggests that our fear of snakes may be innate. The evolutionary psychological explanation of this fear of snakes would be that having an innate fear of snakes proved to be advantageous for survival (snakes are often poisonous), therefore a large percentage of the population demonstrates this trait.

A more complex example may involve the claim that all women are biologically attracted to sexually dominant men. The evolutionary psychological explanation for this would be that for a woman’s genes, it is in their self-interest to seek out the strongest and most powerful genes to replicate with, therefore women who sought out dominant, powerful men would be more likely to survive and replicate, while women preferred weak and submissive men would be less likely. Therefore it’s more natural for a woman to be attracted to a dominant and powerful man.

Another example concerns monogamy. Evolutionarily speaking, the more promiscuous someone is the more likely their genes are to survive and reproduce, implying that natural selection would select in favor of promiscuity. Even despite social constructs of monogamy and fidelity (handed down by power-structures to control property and populations), the humans who still remain promiscuous and cheat on their partners stand the greatest chance of passing their genes on. Indeed, research by biologist Robin Baker suggested that as many as 10% of children are raised by fathers who are not their biological fathers. Therefore it’s more natural for humans to be non-monogamous, even despite social structures such as marriage deeming them to be monogamous.

Makes sense right?

Good. Because the two (common) examples above are the examples I intend to tear to shreds. Let’s start with phenotypes.

Genotypes and Phenotypes

The phenotype is the outward expression and behavior of a genotype. The genotype is the genes which make up the phenotype.

Promise me something. The next time someone tells you that such-and-such behavior is evolutionarily preordained, or that such-and-such physical trait is genetically superior, promise me that you’ll immediately call bullshit on it and not take that person seriously. Generalizations about genetics like this simply cannot be made without massive caveats. Things are not so simple.

When someone says that men are evolutionarily designed to be jealous, what they’re describing is a phenotype. When they say a certain hip-to-waist ratio is genetically superior, they’re actually describing a phenotype.

When discussing “human nature,” people invariably mix up phenotypes and genotypes. Any biologist worth his salt knows better than to claim anything as being “human nature.”

Phenotypes are not determined strictly by the genotype. Phenotypes are determined by some combination of genotype (the genes), the environment (climate, food, resources, etc.) and development (psychological and biological past of the individual). When barley is grown at a low altitude it behaves very differently from when it’s grown at a high altitude — so it makes little sense to ask “what is the true nature of barley” because there is no such thing.

Similarly, a woman raised in a third world country, with a history of psychological abuse will likely exhibit far different sexual behavior from a wealthy woman with a healthy childhood in a first-world country even if they had the exact same genetic makeup. If our sexual and social behavior and attributes were purely defined by our genes alone, then identical twins would behave in the exact same manner in any circumstance. This is simply not true.

Another misunderstanding is the idea that there is a “jealousy gene” or a “promiscuity gene” or a “monogamy gene.” False, false and false. Genotypes are comprised of multiple genes, sometimes hundreds. A change or variance in any of these genes can cause a deviation in behavior. Richard Dawkins, in The Selfish Gene:

“The manufacture of a body is a cooperative venture of such intricacy that it is almost impossible to disentangle the contribution of one gene from that of another. A given gene will have many different effects on quite different parts of the body. A given part of the body will be influenced by many genes, and the effect of any one gene depends on the interaction with many others.”

Also, Stephen Jay Gould in The Panda’s Thumb:

“There is no gene ‘for’ such unambiguous bits of morphology as your left kneecap or your fingernail. Bodies cannot be atomized into parts, each constructed by an individual gene. Hundreds of genes contribute to the building of most body parts…”

The idea that there is some underlying “nature” of human sexuality or monolithic traits that compete and were weeded out of the gene pool are over-simplifications of an extremely complicated system of behaviors which we still do not yet understand completely.

Evolutionary Stable Strategies

Still with me? If not, here’s a video of adorable kittens to give your mind a minute to decompress, because shit’s about to get real here in a second.

OK, so now we understand that phenotypes (what’s expressed) differ from genotypes (the actual genes). Phenotypes are not determined by genes alone. So your ex-wife’s insane jealous are some combination of her environment (i.e., you), her personal developmental history (daddy never hugged her), and of course, her genetics (crazy mother-in-law). We also understand that genotypes themselves are a mass of various individual genes and it’s impossible to point to a single “jealousy gene” or “promiscuity gene” and say that it’s correct, incorrect, better or worse.

Moving on…

Aside from being complex and varied, natural selection doesn’t necessarily always produce one phenotype as the victor. Natural selection may determine that a population stabilize around multiple phenotypes in a certain proportion. (Stay with me, this is important.) This concept is referred to as Evolutionary Stable Strategies and was introduced by the biologist Maynard Smith. Using computer simulations, Smith was able to discover that many populations benefit from not having a single phenotype win out in the gene pool, but maintaining a balance of multiple phenotypes.

To make his point, he constructed a simulation of a population in which two opposite phenotypes were present: people who were aggressive and would fight to the death and people who were passive and preferred to negotiate and make peace. He referred to these as hawks and doves. Hawks would seek to fight and attack others to gain resources and territory. Doves would run away. When two hawks meet, they fight until they kill each other. When two doves meet, they don’t fight. When a hawk meets a dove, the dove runs away.

Intuitively, one would think hawks would eventually kill all of the doves and their genes would dominate the gene pool. Not the case. While hawks are killing each other, doves are enjoying their resources. Every time a hawk kills another hawk, a dove has one less predator. What actually happens is that many of the hawks kill each other off until there is a majority of doves. But once there is a majority of doves, it becomes more and more advantageous to be a hawk, so hawks begin to proliferate once again, killing off the doves for their territory. But once there becomes an abundance of hawks, they begin to kill each other off and it becomes more advantageous to be a dove once again, returning to a balance of hawks and doves.

Without boring you with the mathematics and proof (if you really care, check out Chapter 5 in The Selfish Gene), the population stabilized at a ratio of seven hawks for every five doves, with minor oscillations in each direction.

This was an arbitrary experiment, but what it meant is that being a “hawk” is no better than being a “dove” from the perspective of natural selection. Natural selection chooses a certain ratio of hawks to doves within that particular population. Neither phenotype ever wins out completely; the most efficient means of reproduction is having both present in a certain proportion.

I’m no expert in the field, but it’s not hard to see the applications of this in other areas. The argument that promiscuity is natural, that it’s human nature, whereas monogamy is a social construct and meant for “betas” who are subjugated by the culture around them, one could easily see how having a proper ratio of commitment-minded individuals and promiscuous individuals could create an evolutionary stable strategy. Too may promiscuous people and kids grow up without parents and the nurturing you need. Too many commitment-oriented people and promiscuous individuals have less and less competition. Surely, this evolutionary stable strategy would oscillate and change depending on the economic environment as well. Promiscuity makes sense as a strategy in an environment with low resources, commitment makes more evolutionary sense in an environment with high resources.

This is all guesswork on my part, so don’t take it as gospel. But the point is, as with this entire article, is that nobody knows for sure. Things are complicated.

Distributions Across Populations

Distributions across populations aren’t necessarily limited to one or two phenotypes either. People may not JUST be promiscuous or JUST be commitment-minded. They may be commitment-minded 90% of the time and promiscuous 10% of the time. Or promiscuous in certain situations, but committed in others.

The same goes for women being attracted to more dominant and powerful men. To what degree are they more attracted? Surely, there’s a massive amount of biological variance WITHIN a population of women. Even though the average woman may be attracted to more dominant men, it doesn’t mean that all women are.

Stereotypes usually have a grain of truth to them, that’s why they’re stereotypes. The problem emerges when stereotypes are indiscriminately applied to entire populations. Even worse, is when people discriminate against whole populations in the name of science or biology without understanding the intricacies of genotypes, phenotypes, evolutionary stable strategies, or population distributions.

I find it most useful to consider stereotypes in bell curves. The top of the bell curve (average) may prefer more dominant men, but there’s still a significant segment of the population who don’t. This distribution of phenotype within the population could also shift based on culture or economics.

One could even apply these bell curves to assortment theory (the theory that dating preferences within a population will naturally screen for one another). The majority of women may prefer a man who is taller and the majority of men prefer a woman who is shorter, but there will be a small overlap in which the ends of each bell curve cover one another. Their preferences aren’t right or wrong, natural or unnatural, they’re merely a minority phenotype, and are more likely to find each other and reproduce with one another.

Thinking of things in this manner dispels a lot of beliefs and assumptions that we make about dating, sex, attraction, and gender. Whether it’s a guy who is upset about how tall he is, or a feminist who believes all men cheat, or a blogger who insinuates that all women are simply looking for the next alpha male to come around. Most of these assumptions and stereotypes are veritably false.

Tolerance and Acceptance

We don’t know much about sex. We still don’t even really know why we have sex (as opposed to reproducing asexually). We don’t know why we have two sexes as opposed to three or 27. We don’t know why we have sex in the ways which we do. We don’t know why we have sex more frequently than most species, for pleasure as opposed to most species or why we have sex that doesn’t make babies (oral, anal). We don’t know why female sexuality differs from male sexuality and we aren’t even quite sure what all of those differences are. We don’t know why we have fetishes or sexual dysfunctions. We don’t know why homosexuality exists. We don’t know what definitively creates sexual attraction or why.

We have theories for all of these things — many of them with quite a bit of evidence — but we still have no consensus. We have ideas which are more likely than others and we have ideas which seem more true to us.

I suppose the point of this article is to understand that the ideas which feel more true for you are just that, ideas that feel more true to you. People are different, wildly different. From culture to culture, gender to gender, person to person, everyone exhibits different preferences and desires. Sure, there’s a lot of overlap in many places, including within each gender, but nothing is monolithic, nothing is preordained, and nothing is biologically mandatory.

For this reason, I see a lot of the bickering over gender roles, hypergamy, polyamory and monogamy, fidelity and promiscuity as not-so-sophisticated forms of politics, often promulgated by unknowing actors and actresses, so certain in how right they are. Men are chauvinistic and only care about sex. Women are manipulative and hypergamous. Monogamy is a social-construct and unnatural. Polygamy is immoral and inhuman. It’s all bullshit if you ask me.

What we all need is a little more “not knowing” in our lives. A little more uncertainty. And a little more respect for one another’s differences. You like to be bound in leather and flogged by men in leotards? Cool. You want to fuck every woman you see and never commit to a single one? That’s fine, assuming it’s consensual. You want to wait until marriage until you have sex? Not for me, but OK. More power to you.

And before we wrap up, allow me to switch from amateur biologist over to amateur psychologist for a moment. Perhaps those of us who are most afraid and hateful of the sexualities of others are most afraid of the sexualities within ourselves. Perhaps what we project and hate so much in the populations we accuse — whether they be men, women, homosexuals, “betas” or whatever — is a product of what’s uncomfortable within ourselves.

When people say something “isn’t natural,” what they mean is it’s not natural for them.

And that’s a phenotype most of us have, it’s another evolutionary stable strategy — always tense, always in conflict, but miraculously in balance, rolling forward from generation to generation, person to person. You’re part of something larger than you or I or anyone will ever understand, and that’s a true statement, not a religious one. Enjoy it. And enjoy each other.