It’s no surprise that men are on their best behavior when pretty girls are around but now science backs it up.

Research published in the British Psychological Society’s ‘British Journal of Psychology’ showed men do significantly more good deeds when they’re being watched by the opposite sex — and the hotter a woman is, the more generous they become.

“The research shows that good deeds among men increase when presented with an opportunity to copulate,” said Dr. Wendy Iredale of Sheffield Hallam University. “Theoretically, this suggests that a good deed is the human equivalent of the peacock’s tail. Practically, this research shows how societies can encourage selfless acts.”

In other words, when a guy thinks he might get laid, he tries to impress a woman by doing nice things.The most remarkable part of the study? They thought we needed scientists to figure that out.

[Via ScienceDaily]