A Crash Course on Gender Differences - Session 2

On Men Women and Evolution- Testing the Myth

Posted May 16, 2015

Last week we mentioned:

1. This distinction between human sexuality and that of most animals is related to the fact that raising a human child is a very long and complex process requiring the involvement of more than one parent.

2. . Sexuality most species is based on intense and sometimes violent “sperm competition” between males, along with selective female receptivity to the mating efforts of the males, with only the males deemed most fit on the part of the females succeeding in mating.

We now continue:

The specific characteristics of sperm competition between males vary from one species to another, depending on evolutionary developments. Competition between drones (male bees), for example, comes down to a total of about ten minutes out of their very brief lives. When a virgin queen bee is ready to mate, she enters a vigorous dancing state, drawing a swarm of drones. Only the strongest and quickest drones can succeed in mounting the larger queen bee and inserting their sperm into her. The drones die shortly afterward, while the queen bee stores their sperm for the rest of her life (up to thirty years) for use in fertilizing the millions of ova she produces.

Sperm competition between male mice is no less interesting. Its main expression comes after the act of mating has been completed. After inserting his sperm into a receptive female, the male secretes a sticky substance that essentially blocks the female’s reproductive tract to prevent other males from successfully mating with her until his sperm has been fully absorbed inside the female. This strategy, reminiscent of the chastity belts that the knights of the Middle Ages once locked their wives in before going out to battle, increases the male’s chances of successfully fertilizing a female with whom he mates and also incentivizes him to care for her offspring because he has greater certainty that her offspring are his.

Sperm competition strategies vary widely between species, but generally it is one of two kinds of evolutionary strategies for ensuring the survival of one’s DNA. The other is a “marketing strategy” (think of the peacock’s tail and other characteristics and behaviors that can be explained using the handicap principle) used to increase the attractiveness of individual males in the eyes of females.

Men and women have evolved differences in their emotional and sexual behavior due to physiological differences related to reproduction between the two sexes. Reproductive asymmetries between men and women are expressed in three main ways:

1.      The maximal number of children that a woman can bear in a lifetime is well below one hundred (the best documented historical record of the greatest number of children borne by one woman is held by a Russian peasant woman who lived in the eighteenth century and gave birth to sixty-four children through twenty-seven pregnancies). In contrast, a man can theoretically father 100,000 children. Similarly, while a woman can reach her maximal reproductive potential by mating with only one man throughout her life, a man would need about a thousand women to attain his maximal reproductive potential.

2.         A woman knows with exact certainty who her biological children are: the children emerging from her womb. A man can never be certain whether the children borne by his spouse are indeed his biological children.

3.         In the reproductive process itself mothers invest far more resources than fathers because mothers carry fetuses within them for nine months of pregnancy.

In addition to these three differences, men and women differ in one more relevant physiological actor: men on average have greater muscle mass than women.

To get an idea of the extent to which these physical and physiological distinctions influence differences in emotional reactions and sexual behaviors between men and women, I will review several widespread clichés, taking a close look at each one. Keep in mind that the evolutionary forces that have been shaping differences between the sexes long predate the feminist revolution and the modern era. They existed before human civilization arose, under conditions of a daily struggle for survival in which lack of close care for a child on the part of both parents meant almost certain death for the child.

To be continued next week same time with testing of varoius cliche's on gender differences. Stay tuned!

About the Author

Eyal Winter, Ph.D., is a professor of economics at the Hebrew University and the author of Feeling Smart: Why Our Emotions Are More Rational Than We Think.

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