Women in red dresses have twisted the minds of men for centuries, but a new study shows not only that we find women in red more attractive, but that we also think of them as being more… ahem… available.

Basically, men rate women in red dresses as more interested in sex, hinting that men associate this color with fertility. It’s likely to stem from a biological conditioning from ancient times – when many primate females become fertile, they dilate their blood vessels and their faces become red. This blushing let males know it was time to make their move.

This could be the same for humans, scientists explain, and it’s not about the cut; this works just as well for a red sexy outfit or a red t-shirt. In order to prove this, scientists showed 25 men a photo of a single woman doctored to look, in some cases, like she was wearing a white or red t-shirt. They then asked the men to estimate how interested she would be in romance and intimate contact. In most cases, men interpreted the red outfit as an indication that she was more interested.

“I think [the study] is quite good,” says Paul Eastwick, a social psychologist at Texas A&M University in College Station. “It suggests to me that humans as they exist today exhibit these somewhat odd evolutionary artifacts that haven’t been applicable for some time.”

It’s clear that women, as well as men, should be aware of these elements, especially as they can go both ways.

“Wearing red may be a double-edged sword,” explains Adam Pazda, a psychologist at the University of Rochester in New York state, head of the study. Women “may be getting sexual attention they don’t want.”

Via Science Mag