Forget the pricey perfume. The natural scent of a woman at her most fertile may be enough to attract a mate.

A new study shows that when men smell T-shirts worn by women while ovulating, it  triggers a surge in the sex hormone testosterone.

Researchers say it’s the first study to show that olfactory cues to a woman’s ovulation stimulate a biological response in men that may affect mating behavior.

“Men who smelled a T-shirt worn by a woman on her estimated day of ovulation responded with higher testosterone levels than men who smelled a T-shirt worn by a woman earlier or later in her cycle,” write researchers Saul L. Miller and Jon K. Maner of Florida State University in Psychological Science. “Additionally, consistent with previous findings, our results showed that men perceived women’s odors to be most pleasant right around the time of ovulation.”

In two separate experiments, men smelled T-shirts worn by women for three nights when they were near or far from ovulation according to their menstrual cycle, as well as T-shirts that hadn’t been worn by anyone.

In addition, researchers collected saliva samples from the men and measured their testosterone levels before and after smelling each of the shirts.

The results of both experiments showed that not only did men prefer the scent of the T-shirts worn by the women close to ovulation but they also had higher testosterone levels than men who smelled T-shirts of non-ovulating women or unworn T-shirts.

Researchers say the findings confirm that human mating behavior may be influenced by some of the same sensory triggers found among animals from rodents to primates. For example, the scents released by many species of animals can have a significant impact on their mating behavior.