Can you judge a man by his sweaty t-shirt? This study proves you can.

Researchers asked a group of women to smell a series of men’s sweaty t-shirts, and then rate them for intensity, pleasantness and sexiness (be careful what you sign up for?).

Yes, most of the women preferred less intense B.O. But women in the most fertile phase of their cycle accurately chose the scent of more attractive, symmetrical men—men more likely to pass on good genes to their kids.

Sweat, it seems, is one of the ways we determine if he’s ‘the one.’ Gym, here we come!