Asked by: Anonymous
Need? No. Really, really want? Yes. The cost of reproduction is much lower for a man than a woman. He doesn’t need to carry a foetus around inside him for nine months, nourishing it from his own food supply. Nor does he need to risk his life giving birth to it. So a man’s reproductive fitness is generally improved by having many different sexual partners and this requires a high sex drive.
A woman is better served by being very fussy in her choice of mate and using sex as a bargaining counter to ensure his loyalty and attention. This only works if she can be relaxed enough about sex to withhold it when it is to her advantage to do so. This is not a trick that most men can manage.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.