Women can be as sexually unrestrained as men. In fact, there is a huge overlap in the sociosexuality scores of men and women, with more variation within the sexes than between them. Some researchers are now trying to explain these subtleties in terms of biology and evolution.

Take the fact that women's interest in casual sex can vary wildly over time. A hint that these short-term sexual encounters might have biological and evolutionary advantages comes from the timing of them. Several studies have shown that women are more likely to fancy a fling around the time they are ovulating - although there is no suggestion that this is a conscious decision. Not only that, says David Schmitt of Bradley University, Illinois, women show a shift in preference to men who look more masculine and symmetrical - both indicators of good genes. Women may have a dual strategy going, suggests Schmitt. "Humans infants need a lot of help, so we have pair-bonding where males and females help raise a child, but the woman can obtain good genes - perhaps better genes than from the husband - through short-term mating right before ovulation."...