In general, men are wired to notice obvious signs that convey interest in mating - a warm smile, for example - and ignore other subtleties, like if your lipstick is faded.

A Rolex watch or an expensive car are the things guys often use to show status, wealth, and basic desirability.

It's almost as if men who get tribal tattoos are trying to signal that they are dangerous, they're to be respected, and they're powerful.

Today, American women bear an average of 2.2 children that live to adulthood. Across most of Europe, women bear even fewer young.

As women in industrial societies join the paid workforce, they gain the economic means to depart unhappy marriages more easily.

Both sexes like the exercise and challenge of sports, but for men it's also a basic display behavior for impressing and winning a mate.

The Great Depression of the 1930s saw more American unmarried women working from nine to five, mostly in repetitive, boring, subordinate, dead-end jobs. But the number of working women doubled between 1870 and 1940. During World War II it doubled once again.