04/18/2011 04:33 pm ET | Updated Nov 17, 2011

Why Men and Women Make Different Ethical Choices

Men and women are wired to make different ethical choices. Though we strive for gender equality in our politically correct, post-feminist world, the truth is that moral life is not immune to mammalian biology.1

In fact, sex is an excellent starting point for understanding how our physical differences help to predict our ethics. To begin with, the anatomical contrast between the sex cells of men and women is extreme. The human egg is 85,000 times larger than the human sperm, and the implications of this vast disparity lays the groundwork for moral conflicts between Venus and Mars. A woman produces only about 400 eggs during her entire lifetime (of which only 20 or so can actually become infants). Men release in the neighborhood of 100 million sperm with each ejaculation. "Once he has achieved fertilization, [the male's] purely physical commitment has ended," notes famed biologist E. O. Wilson. Although the man's genes will benefit as much as the woman's, his investment will be far less than hers unless she can convince him to stay and help raise the kids. That, of course, is the ethical rub.

"It pays males to be aggressive, hasty, fickle and undiscriminating ... [and] for females to be coy, to hold back until they can identify the males with the best genes," Wilson continues. "If a man were given total freedom to act, he could theoretically inseminate thousands of women in his lifetime, while women must protect their precious few children." Female humans are relative prudes compared to our ape cousins, it turns out. At her sexual prime, a female chimp advertises her wares with a large pink patch of sexual skin, and for 10 days during a 36-day cycle, she copulates several dozen times a day with every male she can get her hands on. Human males are "moderately polygynous," on the other hand, and initiate most of the changes in sexual partnership. While three fourths of all human societies permit the taking of multiple wives (and most of them encourage the practice by law and custom), a woman's marriage to multiple husbands is sanctioned in fewer than 1 percent of societies.2

Is it any wonder that marriage counselors, divorce lawyers, prostitutes and the corporation that runs Hooters do such thriving business? Because women's bodies have seven times more oxytocin (the "love molecule") than men's, females commit more readily, and easily, than men do.3 While males tend to focus on autonomy, females emphasize relationship. Women need to be more selective about choosing partners, especially under short-term mating conditions, because they're the ones who must care for their young. Men get to have the commitment issues. Women, who need men to stick around, react more aversively to emotional jealousy, while men -- who, before DNA testing appeared, could never be sure about a child's paternity (and inherit a primate aversion to supporting another man's offspring) -- react worse to sexual infidelity.4 This isn't to say that women are okay with being cheated on, or that men are fine when they're emotionally displaced. But women do tend to focus on threats of abandonment while ape-headed, territorial males are fixated on the violation of their chosen female's genitals. In the light of natural selection and biology, such common relationship issues start making greater sense. Women who have dependent children are more at risk from a mate who commits an emotional infidelity, while men are limited by the fact that they can never be certain of paternity because they do not bear offspring themselves. So another thousand Othellos are born.

Boys and girls differ in moral temperament from an early age, studies show. Where boys tend to be more focused on winning, for example, girls are more interested in maintaining relationships, even at a high cost to themselves.5 Primatologist Frans de Waal notes that "impersonal rights and wrongs" are not a top priority for females; compromises that leave social connections intact are. When fights break out in groups of boys, the injured party is expected to get out of the way so that the competition can continue. When the same thing happens among a group of girls, the game stops while all the players gather around to help the girl who is crying.6

Is it any wonder that Mars and Venus collide in their opposing orbits of fair-versus-care? These contrasting orientations can benefit from each other's wisdom, however. While men would be wise to grasp the possibility that there are no absolute moral truths, and that not all people have equal needs, women can be encouraged to separate feeling from thinking long enough to protect themselves from unfair treatment, and walk away when from those who would hold them down. In the end -- in spite of our antithetical bodies, and the contrasting choices they lead us to make -- this is how both sides can come out ahead. We can learn to listen -- and listen to learn from the wisdom of the other side. In this way, we remind ourselves that biology isn't everything, and that choice is always within our means.

As different as our uniforms may be, there's only one team in the human race.

1. E. O. Wilson, "On Human Nature" (Harvard University Press), p. 125.
2. E. O. Wilson, "On Human Nature" (Harvard University Press), p. 126.
3. Jonathan Haidt, "The Happiness Hypothesis," p. 197.
4. E. O. Wilson, "On Human Nature" (Harvard University Press), p. 126.
5. Dan Goleman, "Emotional Intelligence," p. 131.
6. Dan Goleman, "Emotional Intelligence," p. 131.