Tears against violence

New research, publishing December 21 in the open access journal in 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 is less aggressive behavior.

When they made 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 a game, but did not become as active in the same situations when the men were sniffing the tears.

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.