Study: Women's Tears Lower Men's Testosterone, Sex Drive

By Catherine Donaldson-Evans

Men are turned off when women cry, according to a study by Israeli scientists.

The researchers found that female tears led to a drop in men's testosterone levels, which in turn caused a dip in their sex drive.

"This study reinforces the idea that human chemical signals -- even ones we're not conscious of -- affect the behavior of others," lead author Noam Sobel, professor at the Weizmann Institute of Science and Wolfson Hospital in Tel Aviv, said in a statement.

Sobel and his team found a previously unknown chemical in tears from women that triggered a physiological response in men. They called it a "chemo-signal," a type of pheromone. Pheromones are messages transmitted by the sense of smell. Tears, however, are odorless.

A group of men who participated in the study were told to sniff tears that had been collected by women who watched sad movies. Another group was told to breathe in saline solution. A pad with either tears or saline was attached under the men's noses. Then were then asked to rate the faces of women shown to them in photographs.

Surprisingly, the men who'd sniffed tears expressed less sexual interest in the women than those who hadn't.

The next day, the experiment was repeated, with the tears/saline groups switched. Neither the researchers nor the participants knew what they were sniffing. The men had been pre-screened to see whether they could distinguish the scents of tears from saline -- and they could not.

But the results were the same.

"Physiologically the finding makes sense," Dr. Igor Galynker, a psychiatrist at Beth Israel Medical Center with a background in organic chemistry, told AOL Health. "It could be that the odorless tears go into the olfactory system and bind to some receptor that alters hormone levels."

In addition to measuring their testosterone from saliva samples, the men also had their respiratory rates checked and their brains scanned. All suggested a drop in their sex drive.

The scientists didn't measure the impact of men's tears on female sexual arousal because they weren't able to collect enough tears from men, they said.

Researchers in the past have offered up a wide array of theories on why women cry more often then men do. Biochemist William Frey, for example, found that emotional tears contain higher amounts of the hormone prolactin than tears that are brought on by an eye irritation. It was theorized that, because women have more prolactin in their bodies than men, they cry more often.

Though the Israeli study seems to reinforce certain gender stereotypes, Galynker doesn't believe the research is flawed.

"There was no bias," he said. "They needed somebody to produce one milliliter of tears in the course of several minutes. Very, very few humans can do that."

He offered a possible explanation for the response.

"It could be that tears put men on alert that something's wrong," he said. "Sex drive could interfere with that."

The researchers hope their findings, published in Science Express, will help in treatments for prostate and other cancers believed to be linked to elevated testosterone levels.