Research published in PLOS Biology showed that female tears contain chemicals capable of lowering the male hormone testosterone. By smelling it, functional imaging revealed that two areas of the brain associated with aggression were less active
Charles Darwin was particularly upset From human crying caused by emotions, and given that there is no apparent function other than maintaining eye health, it was concluded that Crying is an “accidental consequence” . However, a large body of data since then has convincingly demonstrated that tears serve a function beyond simply defending eye health, as they also serve mammals as a means of social chemical signaling that they can emit on demand.
New research, published December 21 in the open access journal PLoS Biology It turns out that women's tears contain chemicals that prevent aggression in men. A study conducted by Shani Agron at the Weizmann Institute of Science in Israel found this The smell of tears leads to decreased brain activity associated with aggressionWhich leads to less aggressive behavior. The researchers do not offer any suggestions about the possible practical implications of this discovery. But some ideas are worth doing.
It is known that in male rodents, aggression is inhibited when they smell the tears of females. This is an example of Social chemical signalsIt is a common process in animals but less common or less understood in humans. Human tears also contain a chemical signal that lowers the male hormone testosterone, but its behavioral significance has not been clear. as long Low testosterone is associated with decreased aggressionThe researchers tested the hypothesis that human tears act like rodent tears to prevent male aggression.
Signals and chemical behavior
In particular, the authors write: “There are several instances of altered chemical signals Hormone-dependent behavior In humans. Examples include maternal behavior, nutritional behavior, social behavior in general, and sociosexual behavior in particular. In other words, That a chemical signal can change human behavior is not unusual. Moreover, emotional behaviors in particular are excellent candidates for modulation by chemical signals, perhaps a reflection of shared neural substrates in the amygdala complex and the associated extensive brain network spanning the ventral temporal cortex, prefrontal cortex, anterior cingulate cortex, and insula-striatum. “.
“Given this nervous connection Given that Human aggression They add: “It can be measured at the behavioral level using different standardized tasks. We decided to measure the aggressive behavioral and brain response after smelling tears resulting from an emotional state.”
Experimentation through role-playing game
To determine whether tears have the same effect in people, the researchers “uncovered”. Group of 25 men (average age 26 years) To the tears I collected A group of “donors” (6 women between 22 and 25 years old) Or to a saline solution while they are playing a partner game. The game is designed to provoke aggressive behavior towards another The player who the guys thought was cheating.
When given the opportunity, men can take revenge on the other player by making him lose money. The men did not know what they smelled They could not distinguish between tears and saline solution, both of which were odorless. Agressive behavior Seek revenge throughout the game decreased by more than 40% (43.7% to be exact) After the men smelled tears Produced by women's emotions.
MRI and magnetic resonance imaging tests
To investigate Peripheral brain substrates For this effect, tears were applied to 62 human olfactory receptors in the laboratory. Four were identified who responded in a dose-dependent manner to this stimulation. Finally, to investigate Central brain substrates For this effect, the experiment was replicated by subjecting participants to functional magnetic resonance imaging (fMRI).
Imaging showed that two areas of the brain associated with aggression – the prefrontal cortex and the anterior insula – were formed Most active when men are provoked During the match however They have not become active In the same situations that The men could smell the women's tears.
Individually, the greater the variation in this brain activity, the less frequently the player will retaliate during the game. Finding this link between tears, brain activity and aggressive behavior means just that Social chemical cues are a factor in human aggression, not just animal curiosity. “We found that human tears, as in mice, contain a chemical signal that inhibits certain male aggression,” the authors add. This contradicts the idea that tears produced by emotions are uniquely human».
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2 January 2024 (changed 2 January 2024 | 09:15)
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