When it comes to sex, we are consumately proximate

The Guardian “Why the UK sperm bank is running short”

Further evidence that while we are — on the one hand — one of the weirdest species in the world, at our core we remain not unlike the rest of our animal brethren.

Think about it for a second: if humans were both rational and motivated by the goal of increasing our genetic fitness, becoming a sperm donor would be a no-brainer. A lot of anthropologists and evolutionary biologists have suggested that human males have adapted to take advantage of low-cost reproductive opportunities. While most scientists don’t debate the fact that the majority of human fathers go the more expensive route — not just mating but also providing substantial parental care — there does seem to be a secondary strategy at play, one that can involve casual relationships, cheating, or abandonment. Sperm donation seems like an amazing way to add to the male behavioral portfolio. A woman or couple pay you to become a biological father without having to ever waste any effort actually raising your genetic offspring. A good sperm donor could attain truly impressive genetic fitness!

So if being a sperm donor is a great way to maximize your ultimate fitness, why is there actually a shortage of sperm donors? As this article suggests, ejaculating into a cup is just not that appealing to most men, even though from an evolutionary perspective it ought to be.

This tells us some interesting things about ourselves. While we are able to act “rationally” in many situations, that does not mean that our rationality is fine-tuned to our ultimate goals. Instead, our rationality really evolved to help us solve the smaller-scale conundrums that impede our achievement of proximate goals. Those proximate goals make far more sense to us than our ultimate goals.

In this case, the proximate and ultimate goals are pretty clear. Proximately, we like to have sex. But we are pretty picky about how this sex goes down. Sex with an attractive member of the opposite sex, perhaps rather anonymously and without any strings attached? Sure! Sex with ourselves in a clinical laboratory setting? Not so much. Why this is the case makes some sense. While I am sure that masturbation has been an important behavior for our species for awhile, masturbating in a public area probably has not. There are dangers associated with pleasuring yourself in public, so a preference for privacy probably prevailed in the masturbatory habits of our ancestors. But having sex with another person? That is something none of our successful ancestors would have consistently turned down. And having sex with a stranger, or at least sex without attachments, was probably favored under certain circumstances. Why is pretty clear: sex with a member of the opposite sex produces offspring. To desire this sex under the right circumstances (a proximate desire) was likely to lead to successful reproduction (an ultimate goal).

There’s also clearly a cultural component to this behavioral paradox. If all we cared about was making as many babies as possible, the fact that eighteen years later we might be tracked down by a dozen young adults calling us “daddy” would not matter too much to us. But culturally we have a strong sense of what it means to be a father, and the laws that would empower our donation-bank offspring to track us down are a cultural deterrent to low-cost fatherhood. In other words, cultural ideas can actually prevent us from behaving in a way that would maximize our reproductive fitness.

The fact that men are not elbowing each other out of the way in order to donate to the sperm bank also points out that we are — in the end — not that much different from our animal cousins. Like them, what we do is driven far more by our proximate desires than by any rational assessment of what would ultimately lead to maximizing our reproductive fitness.