The Red Queen: Sex and the Evolution of Human Nature

by Matt Ridley

Women with a condition known as Turner’s syndrome (they are born without ovaries) have even less testosterone in their blood than do women who have ovaries. (Ovaries produce some testosterone, though not as much as testicles do.) They are exaggeratedly feminine in their behavior, with typically a special interest in babies, clothes, housekeeping, and romantic stories. Men with less than usual testosterone in their blood as adults—eunuchs, for example—are noted for their femininity of appearance and attitude. Men exposed to less than usual testosterone as embryos—for example, the sons of diabetic women who took female hormones during pregnancy—are shy, unassertive, and effeminate. Men with too much testosterone are pugnacious. Women whose mothers were injected with progesterone in the 1950s (to avert miscarriage) later described themselves as having been tomboys when young; progesterone is not unlike testosterone in its effects. Girls who were born with an unusual condition called either adrenogenital syndrome or congenital adrenal hyperplasia are equally tomboyish. This disorder causes the adrenal gland, near the kidney, to produce a hormone that acts like testosterone instead of cortisol, its usual product.