New research indicates that women's tears play a unique role in reducing aggression in men.
The study, conducted at the Weizmann Institute of Science, utilised behavioural measures, brain imaging, and molecular biology to explore the impact of odourless chemicals from human tears on individuals.
The findings suggest that women's tears act as a chemical peacemaker, lowering aggression in men who are exposed to the scent. This conclusion was supported by human behavioural studies, brain imaging, and molecular biology experiments. The researchers believe this mechanism may be shared among many mammals.
The study challenges the idea that tear production is exclusive to humans, pointing out examples in other mammals such as dogs and mice. Tears, in various species, have been found to convey molecular signals that influence social behaviour and aggression.
The research team collected tears from volunteers who watched sad movies, and male participants who sniffed women's tears showed a significant reduction (almost 44%) in aggression during a competitive game. Brain imaging revealed changes in activity in regions associated with aggression and decision-making.
The study also identified four human olfactory receptors responding specifically to tears, providing insight into how pheromonelike signals are processed in humans.
Future experiments are planned to explore the effects of women's tears on other women and the impact of baby tears on adults. The researchers hypothesise that baby tears, in particular, may have an aggression-lowering effect on adults, serving as an evolutionary tool for communication.
The study suggests that tears, often associated with emotional expression, may have evolved as a behaviour that serves a purpose in regulating social interactions and aggression throughout life.