The Prudent Gene
Humans are capable of two types of selfishness, the prudent kind and the imprudent kind. Imprudent selfishness is quite common: a glutton grabs the cake from someone else and gorges himself on it, much to his future detriment. The genes, however, do not go in for this kind of imprudent selfishness; their selfishness is exclusively of the prudent kind. It is easy to see why: imprudent genes don’t stay in the gene pool, since they don’t maximize their own survival prospects. So we can say that genes have, in addition to the trait of selfishness, the trait of prudence: the genes that survive best are the ones that program their carriers to act prudently with respect to gene survival. That doesn’t mean with respect to individual survival: an organism can serve its genes by acting so as to benefit its offspring more than itself. What a gene will not do is produce organisms that act altruistically in an imprudent manner with respect to those genes. Genes work to produce organisms that protect the interests of their genetic descendants: that is, they act prudently with respect to their own future survival. They don’t do silly things like gamble their survival on the lottery, or construct organisms that laze around all day. The genes are not prudentially irrational. Genes operate by a principle of enlightened self-interest.
But this raises a question about imprudent animal behavior: why do animals sometimes act so as to not maximize genetic survival? Why are they imprudent with respect to their genes? Mostly they are prudent in this way, by storing food for later consumption, or not fighting bigger animals, or building nests and other dwellings. They plan for the future, ensuring their own survival and that of their genes. That’s how the genes built them. Then why isn’t this a universal law? Consider masturbation, not just in humans, but also in a wide range of other species (elephants, walruses, squirrels, turtles, etc.): isn’t this imprudent with respect to gene survival? Isn’t it a waste of good genes? Even if there is no ejaculation, it is sexual behavior not spent on reproductive success. The chronic masturbator is not much of a reproducer. A gene for masturbation would not stick around for long, unlike a gene for copulation. Yet masturbation is common and normal in many species. Genes for masturbation don’t seem very prudent—even if they form part of what makes an organism happy. Thus masturbation presents a problem for prudent gene theory.
The only possible solution to this problem is to regard masturbation as an unwanted side effect of a trait that is prudent from the genes’ point of view. But it is hard to see how such a side effect could withstand the test of natural selection: how could natural selection favor, or even tolerate, a trait that could lead to gene termination? Think of an animal that does nothing but, leaving copulation to others—its genes will not get passed onto future generations. I am led to conclude that the existing arrangement is a compromise solution to a difficult engineering problem. The genes need to motivate animals to reproduce, and pleasure is a powerful motivator; but then the loci of pleasure can be stimulated in other ways, thus producing non-reproductive sexual activity. But how can the genes prevent animals from abusing the system they have created? They agree that masturbation is genetically imprudent, and they are paragons of prudence, but they can’t think of a way around the problem: if you reduce sexual desire in order to discourage masturbation, you end up discouraging copulation. If masturbation in turtles became too common, reducing copulation significantly, then turtles would be in reproductive trouble; but as things are the balance just about allows for the coexistence of prudent copulation and imprudent masturbation (with respect to gene survival). The problem is a little like the problem of pain: it is so important to give organisms the sensation of pain for ensuring survival that the genes tolerate a downside to pain that serves no survival purpose. Masturbation looks like a waste of resources and energy that could be devoted to surviving and reproducing, and it is just that; but the genes tolerate it because otherwise animals would not be equipped with the motivational apparatus that propels them towards reproductive copulation. The genes are scrupulously prudent, but even they know when they are beaten: they can’t put a stop to masturbation without undermining reproductive motivation. Either that or masturbation is a complete mystery and a blot on the genes’ reputation for prudence. 
 It is generally easy to see why imprudent behavior, such as overeating and sugar consumption, is an offshoot of adaptive traits, but the existence of masturbation in many (but not all!) species is far more puzzling. They do it a lot and it is quite contrary to the genes’ interests. There ought to be a gene for not masturbating.