Crying isn't sexy—unless you're a male mouse. Researchers have found that a previously-identified pheromone in male mouse tears, known as ESP1, makes female mice arch their back, lift their hind region, and stay put when the males approach them to mate. (Female mice not in the mood tend to run away.) Scientists have found mouse pheromones in urine before; pheromones in tears may have evolved because tear fluid lingers in the fur, and female mice often groom the faces of other mice, the team will report tomorrow in Nature. Women don't have the receptor for this pheromone, however, so hold back on those tears for now, guys.