At least for male mice, shedding a tear can draw some females their way.
A new study has shown that male mouse tears contain a sex pheromone called ESP1, which makes female mice more receptive to mounting, reports National Geographic.
Study co-author Kazushige Touhara of the University of Tokyo, said that while sex pheromones are known to have similar effects in other animals, the new study shows for the first time how the interaction works "at the molecular level and also the brain level."
Male mice shed tears to keep their eyes from drying out. As they groom themselves, the tears-and the pheromone-get spread around their bodies and nests.
When female mice come in contact with a male or his nest, they pick up the pheromone via a nose organ called the vomeronasal, where the pheromone binds to a specific protein receptor.
"She has to touch it, because this is not a volatile compound like a fragrance," Touhara said, referring to the ease with which some chemicals turn into vapor.
Upon contact, the pheromone is sent to sex-specific regions in the female's brain. The female mouse is then three times more likely to engage in what's called lordosis behavior, a posture shown by many animals in heat in which they thrust their rumps and tails upward.
The findings may have real-world applications for mouse population control.
The findings appear in this week's issue of the journal Nature.