Sniffing women’s tears reduces male aggression
By PLOS
New research, published on December 21st in the open-access journal PLOS Biology, shows that tears from women contain chemicals that block aggression in men.
The study led by Shani Agron at the Weizmann Institute of Science, Israel, finds that sniffing tears leads to reduced brain activity related to aggression, which results in less aggressive behavior.
Human Response to Emotional Tears
Male aggression in rodents is known to be
blocked when they smell female tears. This is an example of social
chemosignaling, a process that is common in animals but less common—or less
understood—in humans.
To determine whether tears have the same effect on people, the researchers exposed a group of men to either women’s emotional tears or saline while they played a two-person game. The game was designed to elicit aggressive behavior against the other player, whom the men were led to believe was cheating.
When given the opportunity, the men could get
revenge on the other player by causing them to lose money. The men did not know
what they were sniffing and could not distinguish between the tears or the saline,
which were both odorless.
Impact of Tears on Aggression and Brain Activity
Revenge-seeking aggressive behavior during
the game dropped more than 40% after the men sniffed women’s emotional tears.
When repeated in an MRI scanner, functional imaging showed two
aggression-related brain regions—the prefrontal cortex and anterior insula—that
became more active when the men were provoked during the game, but did not
become as active in the same situations when the men were sniffing the tears.
Individually, the greater the difference in
this brain activity, the less often the player took revenge during the game.
Finding this link between tears, brain activity, and aggressive behavior
implies that social chemosignaling is a factor in human aggression, not simply
an animal curiosity.
The authors add, “We found that just like in
mice, human tears contain a chemical signal that blocks conspecific male
aggression. This goes against the notion that emotional tears are uniquely
human.”
Reference: “A chemical signal in human female
tears lowers aggression in males” by Shani Agron, Claire A. de March, Reut
Weissgross, Eva Mishor, Lior Gorodisky, Tali Weiss, Edna Furman-Haran, Hiroaki
Matsunami and Noam Sobel, 21 December 2023, PLOS Biology.
DOI:
10.1371/journal.pbio.3002442