Men who smell women's tears act in unexpected ways

All land mammals have tear glands in their eyes, but for a long time they were thought to function only as a lubricant. Although emotional tears are thought to be limited to humans, researchers have found that secretions from these small glands in other mammals contain chemicals that act as social signals with calming functions.

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Such chemicals are also found in humans, a A study conducted by scientists from the Weizmann Institute of Science showedSmelling a woman's tears reduces the activity of the brain area associated with aggression in men. Details are described in the magazine PLoS Biology.

Shani Agron, a doctoral student from the professor's laboratory. Noam Sobel of the Weizmann Institute of Science says:

We knew that smelling tears lowered testosterone levels and had a greater effect on aggression in men than in women, so we started examining the effects of tears in men because this gave us a better chance of observing the effect.

Tears of reassurance

Every ophthalmologist will tell you that the function of the tear film is to protect the eye from possible damage, remove impurities from it, and reduce friction between tissues. Tears are a natural product of our body, they moisturize the eyes and help avoid eye strain when staring at a screen for a long time. The tear film is produced by the tear glands located in the upper corner of the eye socket – hence the ducts that allow tears to be delivered to the conjunctival sac.

Read also: Human tear glands grew and made her cry. What was the aim of the study?

But when we ask a psychiatrist about the importance of a tear film, he will give a completely different answer. Previous research has shown that women's tears contain odorless chemical signals that, when inhaled by men, reduce sexual arousal as well as testosterone levels. When men smelled women's tears, their aggression during the revenge game decreased by about 44 percent, or nearly half.

This appears to be equivalent to the effect seen in rodents, but these animals have a structure called the vomeronasal organ (VNO) that picks up social chemical signals. Humans probably don't have this organ, so how can they sense social chemistry? To find the answer, the researchers applied tears to 62 human olfactory receptors in a laboratory dish, and found that four of these receptors were activated by tears, even though tears are odorless.

That's not all. Repeating experiments scanning the men's brains using functional magnetic resonance imaging (fMRI) showed that two regions associated with aggression — the prefrontal cortex and the anterior insula — were less active when the men smelled tears. The greater the difference in activity of this area between salt water and tears, the less “acts of revenge” will occur during the game.

Professor Noam Sobel sums up:

We have shown that tears activate olfactory receptors and change brain circuits associated with aggression, significantly reducing aggressive behavior. These findings suggest that tears are a chemical cloak that provides protection against aggression, and that this effect is common in rodents, humans, and perhaps other mammals as well.

Recent research has shown that dogs also produce emotional tears, but more research is needed to determine whether they contain chemical signals that can be detected by other dogs or humans.