The Mating/Reproduction Game

Dad or Cad, Lusty or Trusty

Alma, tell us
All Modern Women are Jealous
--Tom Lehrer, Alma

In the game of evolution, the object is to reproduce. Our behavioral traits can be interpreted as unconscious strategies for playing the game. These traits then interact with the cultural environment, which can change rapidly.

I will present some speculations, which I hesitate to dignify with the term “theory.” Primarily, I want to emphasize that mating strategies are contingent. No single strategy is necessarily going to be followed.

One point is arithmetically certain. In a society with equal numbers of males and females, the average number of heterosexual sex partners will be the same for men and women. The average number of sex partners for men is n/m, where n is the number of pairings and m is the number of males. For women, it is n/f, where f is the number of females. If n=f, the averages will be equal. Men may desire more sex partners, but the average has to turn out to be equal.

A wealthy, powerful man, such as Genghis Khan, can afford to be a Cad. Women will be willing to share his resources. If some men succeed at having many sex partners, then other men must have very bad luck in that department.

Men and women have different possibilities to worry about. A woman knows that a child is hers, but she has to worry about whether a man will provide resources to help sustain her and the child. A man is less physically vulnerable, but from a reproduction standpoint he has to worry about wasting resources by contributing them to a support a child that is not his.

Here is a simple either-or strategic choice for how men and women can present themselves. A man may present himself as either a Dad or a Cad. A Dad signifies that he will faithfully devote time and resources to the children of just one woman. This creates a presumption that he will only try to mate with one woman. A Cad signifies that he will increase his chances of reproduction by trying to mate with many women.

A woman may present herself as a Trusty or a Lusty. (I made up these terms myself, for this essay.) A Trusty signifies that she will only mate with her husband, so that he can trust that the children he is supporting are his. One way to do this is to signify some reluctance to engage in sex. A Lusty signifies that she has a strong sex drive. She is likely to have plenty of men who are attracted to her. I interpret Tom Lehrer’s ballad “Alma” as describing a Lusty.

Note that I am careful to use the term “signify.” It is easy to imagine circumstances in which someone tries to hide their actual inclinations. In an environment in which Cads are popular with women, someone who is inclined to be a Dad will try instead to signify as a Cad. In an environment in which women want to attract Dads, a woman with a strong sex drive might still try to signify as a Trusty.

Late in life, a Dad may abandon a Trusty. He may indulge a desire for a Lusty. Was the man a Cad all along?

A Lusty arouses cultural hostility. It is in the interest of both men and women to try to suppress the Lusty. A man would be afraid of devoting resources to a child who might not be his own. This gives him a reason to try to control his partner’s sex life. It seems plausible that an overall patriarchy emerges as a result of men in general trying to control female sexual behavior.

A woman does not want a Lusty to take away her man’s attention and resources. It is also plausible that women evolved a strategy of trying to make a rival unattractive to Dads by portraying her as a Lusty.

Increased urbanization reduces the penalty for being a Lusty. You can escape from intense gossip more easily in a city than in a small village.

What strategies are the people around you following? If the men are mostly Cads, being a Trusty may not be successful. If the women are mostly playing a Trusty strategy, being a Cad may not pay off.

The classic 1950s marriage in the United States was between a Dad and a Trusty. In novels and movies there was great fascination with the Cad and the Lusty, but one was supposed to be wary of the former and shun the latter.

I think that the sexual revolution that began in the late 1960s and really took hold in the 1970s served to raise the status of the Lusty. Perhaps this was enabled by the availability of reliable birth control, which served to reduce a man’s fear that a Lusty partner would saddle him with the burden of another man’s child. The patriarchy was made obsolete by The Pill.

But I don’t think that we should under-estimate the sheer cultural change that took place. The status of a Trusty who refrained from premarital sex went from very high to very low with astonishing speed. The idea that society had a right and/or responsibility to restrict women’s sexual behavior met with powerful and effective resistance.

In some environments, such as college campuses that were majority female, it became difficult for a Trusty to compete for attention from males. This in turn encouraged more men to indulge in a Cad strategy while in college.

When a man’s ability supply resources is not compelling, either because a woman has her own resources or the man cannot earn a good living, it becomes difficult to follow a Dad strategy. Arguably, we are seeing this today among men who have not graduated college and who have not taken up a lucrative trade. Such men may have little alternative but to try their luck as Cads. For women who have to choose from among such men, there may not be much point in trying to follow a Trusty strategy.

The net result is that college-educated people are able to form the traditional Dad/Trusty marriage, but not until age 30 or later, when the men are ready to give up the Cad lifestyle. And people without a college education are stuck in the pattern of transitory Cad/Lusty pairings.

I should emphasize that I do not think that people follow conscious strategies. In my view, some people are born with traits that make it more plausible to follow one strategy or another. But the cultural environment affects the incentive for how people behave. We are not strictly programmed by biology. Culture is very important.

This essay is part of a series on human interdependence.