The Moral Animal

The Moral Animal introduces you to the fascinating world of evolutionary psychology and uncovers the genetic strategies that explain why we do everything we do.

Jealousy is historically thought of as a negative, ugly characteristic. But though we might try to hide it, jealousy is an entirely natural emotion for human beings. All of us feel it from time to time. But interestingly, men and women experience jealousy very differently

In a 1982 experiment researching sexual jealousy, scientists attached electrodes to both male and female participants to measure physiological responses. They asked participants to either picture their partner having sex with another person or to picture their partner forming an emotional bond with a person of the opposite gender.

Surprisingly, men and women responded very differently to both scenarios. For the men, picturing their significant other having sex with another person led to signs of distress and anger. The idea of their partner being close friends with another male left them unmoved. Women, on the other hand, showed a much more distressed response to the idea of their partner forming an emotional attachment with another woman than the idea of sexual infidelity.

Why is this? Evolutionary psychologists explain that a male’s unconscious desire to propagate their genes drives their sexual jealousy. Picturing their partner in a sexual relationship with another man stung so much because the idea that another man could impregnate their partner and they could end up rearing a child without their own DNA is enraging. Nowadays with contraceptives, sex and pregnancy aren’t automatically mutually exclusive. An affair is far less likely to result in pregnancy. However, the reason it remains so enraging to men is because of an evolutionary reflex.

Have you ever felt your parents favored another sibling over you? Remarkably, Wright uncovers that evolution can even influence child the family prefers, and specifically, which gender. Evolutionary psychologists explain parents favor the gender that has the greater potential to carry on the family’s genes. This ability to pass on genes historically differed based on what social class the family comes from. In a poor family of low status, it was usually the girl. Girls had more of a chance to marry “up” into a family that is wealthier. In the wealthier family, the boys were favorites. This is because boys could spread their genes because of their power to find any woman or even multiple partners. A study of medieval Europe and nineteenth-century Asia, anthropologist Mildred Dickeman says that killing females before their first birthday, or infanticide, was staggeringly more common among the aristocratic families than the poor. And even when there wasn’t the extreme action of infanticide, they much more frequently gave inheritances to the…