When women cry, they may be lowering the testosterone in men nearby.
Men were given jars containing either tears collected from women who watched a sad movie, or saline drops that were trickled down the same women’s faces. Though they reported smelling no difference, the men who sniffed tears experienced drops in testosterone and were less likely to find photographs of women attractive than the men who smelled saline, according to Israeli research published today by the journal Science.
Tears produced from emotion are chemically different from those produced to moisturize the eyes, and no nonhuman animals produce them, said Robert R. Provine, a professor at the University of Maryland Baltimore County. Though Provine’s previous research found tears communicate sadness more strongly than facial expressions alone, this is the first evidence that tears’ influence may be more than visual, he said.
“Tears aren’t just something we produce when we’re sad, they’re a message sent to other people,” Provine, who was not involved with the study, said in a telephone interview. “This paper shows that the signaling function of tears can be chemical as well as visual.”
Tears have long been presumed to halt aggressive behavior, Provine said. The reduction in testosterone observed in the study may begin to explain why, he said.
The researchers, led by Shani Gelstein and Yaara Yeshurun at the Weizmann Institute of Science in Rehovot, Israel, used female tears because crying is considered more culturally acceptable for women than men, they wrote in supplementary material to the paper. 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.
The paper is intriguing for the implications it may have on influencing the brain, said Kennedy Wekesa, a professor of biology at Alabama State University in Montgomery, Alabama. Though the paper demonstrates an effect, it isn’t clear how the tears activate the human brain or what path they use to get there, Wekesa said.
“It’s an interesting study,” said Wekesa, who wasn’t involved in the paper, in a telephone interview. “It brings more questions than it answers.”
Additionally, humans produce tears for reasons other than sadness, Wekesa said. Another study to see if tears of joy have the same effect would be worthwhile, he said.
The research was funded by the Minerva Stiftung Foundation based in Munchen, Germany.