Do men crave sex more than women, or do the ladies have better self-control? It's an ongoing debate in the sexual science community, but researchers from the University of Texas say the answer is simple: Guys are just hornier.

Compared to women, men had a much harder time rejecting photographs of attractive members of the opposite sex—even when they were instructed to do so, the research shows. Follow-up tests found guys have just as much self-control as women, but their impulse to accept sexy partners is nearly four times stronger.

All the old evolutionary arguments help explain these differences, says study coauthor Paul Eastwick, Ph.D. Because sex could lead to pregnancy and labor—burdens that fall on the female—women evolved to be more selective about who they sleep with. Eastwick says society’s acceptance of men’s dalliances (but not women’s) may also have shaped the strength of a guy’s sexual impulses. As a result, dozens of studies have confirmed that men fool around more than women.

Unless your testosterone levels plummet (that's bad), your sex drive will stay the same, Eastwick says. But you can take steps to pump up your self-control. Your willpower tends to lag when you’re tired, he warns. So going out on a Friday night after a long week of work may lead to trouble.

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