Human Tears and Behavior

Human tears may be sending chemical signals meant to influence other people's behavior.
On its front page, the New York Times (1/7, A1, Belluck) reports, "When we cry, we may be doing more than expressing emotion." In fact, "our tears, according to striking new research, may be sending chemical signals that influence the behavior of other people." The paper appearing in Science may "begin to explain something that has baffled scientists for generations: Why do humans, unlike seemingly any other species, cry emotional tears?"
According to the Time (1/6, Szalavitz) "Healthland" blog, "fluids similar to tears are used to send chemical signals" among mice. "For example, male mice become more aggressive when exposed to these fluids from other males. In humans, sexual attraction and the menstrual cycle are known to be influenced by odors."
What's more, "emotional tears previously had been shown to be chemically distinct from reflexive, eye-protecting tears," the Los Angeles Times (1/7, Khan) reports. So, "perhaps human tears contained a chemical signal too." With that in mind, researchers in Israel "asked six women to watch triple-hanky chick flicks," and collected their tears, thinking the "tears would trigger feelings of sadness or empathy" among men. Instead, the "50 tear-sniffing men whose testosterone levels were tested experienced a drop averaging 13%," and "sniffers who viewed erotic images before submitting to an MRI showed less activity in the sexual arousal regions of their brains, too."
Notably, the team at the Weizmann Institute of Science "used female tears, because crying is considered more culturally acceptable for women than men," Bloomberg News (1/7, Lopatto) reports. But, the "researchers don't think the signals from tear chemicals are unique to women, they wrote, and they may also occur in crying men and children."
Interestingly, the research "places human tears in a family of fluids that includes urine and anogenital gland secretions," the Washington Post (1/7, Brown) reports. In other words, "what we have found is that human emotional crying may not be so unique after all," explained lead investigator Noam Sobel. "It is a reflection of something common to many, if not all, mammals, which is chemosignaling through lacrimal secretions."
The USA Today (1/6, Vergano) "Science Fair" blog, HealthDay (1/6, Salamon), and WebMD (1/6, Hendrick) also covered the story.