Carla’s Reviews > The Red Queen: Sex and the Evolution of Human Nature > Status Update

The process of choosing somebody to have sex with, which used to be known as falling in love, is mysterious, cerebral, and highly selective: We do not regard any and all members of the opposite sex as adequate partners. We consciously decide whether to consider people, we fall in love despite ourselves, we entirely fail to fall in love with people who fall in love with us. It is a mightily complicated business.

The fact that one segment of the population is having sons makes it rewarding for the other segment to have daughters. Every animal is the child of one male and one female. So if dominant animals are having sons, then it will pay subordinate ones to have daughters.

Lower down the social scale, daughters are preferred even today: A poor son is often forced to remain single, but a poor daughter can marry a rich man.

So human society, like ape society but unlike most monkey society, is a female-exogamous patriarchy, and sons inherit their father's (or mother's) status more than daughters inherit their parents' status. Therefore, says Trivers-Willard, it would pay dominant fathers and high-ranking mothers, or both, to have sons and subordinates to have daughters: Do they? The short answer is that nobody knows.

Far from settling down to a fair and reasonable way of determining gender, nature has to face an infinite series of rebellions: It suppresses one only to find it has opened the way to another: For this reason gender determination is a mechanism full of, in the words of Cosmides and Tooby, "meaningless complexity manifesting unreliability, aberrations, and (from the individual 's point of view) waste."

Maleness is a rather rare commodity at this stage. The few
remaining hermaphroditic mice are at a premium because only they
can produce the sperm that the all-female mice still need. The rarer
they get, the better they do. No longer does it pay to have the
male-killing mutation: Rather, the reverse. But if such a female
killing gene appeared, then the remaining hermaphrodites are no longer
at a premium.

Maleness is a rather rare commodity at this stage. The few
remaining hermaphroditic mice are at a premium because only they
can produce the sperm that the all-female mice still need. The rarer
they get, the better they do. No longer does it pay to have the
male-killing mutation: Rather, the reverse. But if such a female
killing gene appeared, then the remaining hermaphrodites are no longer
at a premium.

"Now a selfish gene might do rather well. Suppose it simply killed off its opposite number. Such a gene exists. Call such a gene Cain. The 'mask of Cain' protects him from the gas he uses against Abel. Cain becomes an ancestor, and Abel does not. Thus a gene for chromosomal fratricide will spread as surely as a murderer will inherit the Earth."

To be sexual does not necessarily imply the need for sexes, let alone for just two sexes, let alone for two sexes as different as men and women.

Indeed, at first sight, the most foolish system of all is two sexes because it means that fully 50 percent of the people you meet are incompatible as breeding partners.