Things pop into my mind for no discernible reason.

[aadler]

Today, I just got reminded of the very familiar question I can remember hearing as far back as the Eighties (maybe even before that, but I specifically remember it then): “A guy who sleeps with a lot of women is called a stud. A woman who sleeps with a lot of men is called a slut. What’s fair about that?”

Well, no, it isn’t fair. But it isn’t just sexism, either. There’s a reason. Not a nice reason, but one based on reality. (You know, that thing that keeps hanging around even if you refuse to believe it?) It comes down to a single word: optimization.

On a strictly physical basis, how much investment does a man have to make to reproduce? Technically, a minute or two, sometimes only seconds; once he delivers ejaculate, his absolutely necessary contribution is complete.

How much reproductive investment is required of a woman? Without substantial medical support, at least 32 weeks (the time required to deliver a viable infant, and more is better up to 40 weeks). Worse than that: though there are obvious outliers, the prime reproductive age for women falls between 16 and 24; fertility diminishes after that, and drops sharply after age 35. By contrast, men produce motile spermatozoa from puberty till death.

What this means in practical terms is that prime reproductive strategy for a male is to have sex with as many women as possible: more pregnancies, more descendants. The most prominent example of this is Genghis Khan: it’s been genetically established that he is the ancestor of 1 in every 200 men worldwide, and fully 8% of all males in the region of the former Mongol empire.

Women, on the other hand — because sperm is cheap and plentiful, while eggs/wombs are in limited supply — will do best by reproducing with the best possible man. (“Best” being measured two ways: best genetic contribution, and best paternal support.) Genghis Khan was the absolute winner in the genetic lottery; second place, however, would be shared by all the women through whom he reproduced. How do we know? Because their descendants are still here.

This is why different marital customs favor different people in terms of reproductive success. In monogamy, the winners are higher-status women and lower-status men. (The higher-status women have a better chance of monopolizing the higher-status men; the lower-status men have a better chance of there being women left over for them.) In polygamy, the winners are higher-status men and lower-status women. (The higher-status men get more women, the lower-status women have a decent chance of either being the second-third-etc. wife of a high-status man, or getting a higher status man than they otherwise would, simply because after the high-status men pick off the best women, there are more men to go around for the women remaining.)

Again, these are purely in reproductive terms. If you don’t care about reproducing, if you don’t want to reproduce, these considerations may not seem to have anything to do with you. The problem is that these things are hard-wired into us: not just in our drives (the sexual drive comes from the drive to reproduce), but in what we find desirable. What do men desire in women? many things, but primarily youth and beauty (perceived probability of being able to bear healthy children). What do women most desire in men? Well, there’s a dual track there: Track One is young, handsome and aggressive (perceived probability of being able to sire children more likely to survive and succeed), while Track Two is wealth and status (perceived probability of being better able to care for her descendants, from the Track Two man or from prior births).

Either way, saying it again: a man’s best reproductive strategy is to spread his seed as widely as possible; a woman’s best reproductive strategy is to limit herself to the best possible candidate (which may well include trading up to the next-higher-status man whenever possible). This is not moral; in fact, morality — in terms of what provides the best outcomes for children — would dictate sex (reproduction) only within marriage, and marriage as a lifelong arrangement, neither of which accord with the prime reproductive strategy for an individual.

On a strictly pragmatic basis, then, a man who sleeps with a lot of women is — justly or not — the subject of some regard because he is maximizing his likelihood of reproductive success. Conversely, a woman who sleeps with a lot of men is failing to maintain her optimum reproductive strategy; she’s being too undiscriminating, not restricting herself to the best candidates she can reach.

It may not be fair … but there are reasons for it, and the reasons aren’t based on nothing.