Many of us think we know the answer to that one. Three obvious guesses might be: For pleasure, because theyre in love, or to have children. And we might think of a few more if we worked at it. David Buss and Cindy Meston asked 1,500 women why they had sex, and they came up with a list of 237 different reasons. The research covers sexual attraction, orgasm and pleasure, love and bonding, and such things as sexual competition among women, and effects on social status and reputation.