The Red Queen: Sex and the Evolution of Human Nature

by Matt Ridley

A few more technical terms are essential, and then we can discard the whole jargon-ridden dictionary of genetics. The first word is “meiosis,” which is simply the procedure by which the male selects the genes that will go into a sperm or the female selects the genes that will go into an egg. The man may choose either the 30,000 genes he inherited from his father or the seventy-five thousand he inherited from his mother or more likely, a mixture. During meiosis something peculiar happens. Each of the 23 pairs of chromosomes is laid alongside it opposite number. Chunks of one set are swapped with chunks of the other in a procedure called “recombination.” One whole set is then passed on to the offspring to be married with a set from the other parent—a procedure known as “outcrossing.” Sex is recombination plus outcrossing; this mixing of genes is its principal feature. The consequence is that the baby gets a thorough mixture of its four grandparents’ genes (because of recombination) and its two parents’ genes (because of outcrossing). Between them, recombination and outcrossing are the essential procedures of sex. Everything else about it—gender, mate choice, incest avoidance, polygamy, love, jealousy—are ways of doing outcrossing and recombination more effectively or carefully.