Smelling Women's Tears Changes Men's Behavior, Psychologists Find

Scientists have found an unusual way to reduce aggressive behavior in men—sniffing a woman's tears.

It may sound bizarre, but a new study published in PLOS Biology found that men who sniffed a woman's tears before playing a competitive game, were significantly less aggressive.

Crying is a natural response to feeling sad but scientifically, it has not always been widely understood. Charles Darwin himself was confused by the phenomenon, as it appeared to have no "apparent function," the study reports. But modern science is proving that this may not be the case.

Rodents also have the ability to cry and when male rodents smell female tears, they are less aggressive. It is a form of social chemosignaling—a process whereby chemicals evoke a range of reactions.

Scientists do not know a lot about this process in humans, but lead author Shani Agron at the Weizmann Institute of Science, Israel, set out to discover more.

"Given previous findings showing lower testosterone levels in men following sniffing tears and the findings in rodents showing that tears reduce aggression, we hypothesized that tears would act the same in humans; however, we were surprised by the size of the effect in the lab," Agron told Newsweek.

To reach her findings, Agron exposed a group of men to either women's tears, or saline, without them knowing which. They were exposed to the substance while playing a game, which was specifically designed to provoke aggression. For example, the men were led to believe that the other player was cheating, which would usually provoke "revenge-seeking behavior."

When the time came, the men were able to get their own back on the other player. Scientists discovered that the number of those who decided to take revenge on the "cheating" player decreased by more than 40 percent after men sniffed women's tears.

"A 44 percent reduction is not something typically seen in lab settings. It was also surprising to learn that some olfactory system smell receptors can respond to tears despite their lack of odor," Agron said.

The researchers also analyzed the prefrontal cortex and anterior insula—two regions of the brain associated with aggression. These regions were a lot less active in men who had sniffed a woman's tears before playing the game. It was also noticeably more active during the game in men who had only sniffed saline.

"Tears are a bodily fluid that is produced when an individual is in a vulnerable situation where non-verbal communication is crucial. These tears emit a chemical signal that helps lower aggression, which is beneficial. This mechanism probably gains even higher importance for babies," Agron said.

These findings suggest that social chemosignaling does in fact occur in humans, and is not exclusive to animals.

"We tested the effect of tears on men because we wanted to start where we had higher chances of seeing an effect," Agron said. "We knew that sniffing tears lowers testosterone, and lowering testosterone has a greater effect on aggression in men than in women, so we started with them. We must, however, now replicate in women to obtain a fuller picture of this behavior."

This study was first undertaken in just men, because women's tears were more widely available.

"When we looked for volunteers who could donate tears, we found mostly women, because for them it's much more socially acceptable to cry," Agron said in a press release. "We knew that sniffing tears lowers testosterone, and that lowering testosterone has a greater effect on aggression in men than in women, so we began by studying the impact of tears on men because this gave us higher chances of seeing an effect."

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