Smelling female tears reduces aggression in men

New research published in PLOS Biology has outlined how a chemical signal in female tears can reduce aggressive behaviour in men.

As part of the study, a group of six women signed up to donate their tears.

The donors were instructed to remove any cosmetics before donation day. The women watched sad films in isolation, before using a vial to capture the tears rolling down their cheeks.

“A typical donation used in this study contained approximately 1.6 ml of tears,” the study authors explained.

The tear donors completed a questionnaire covering a range of topics, including the emotions they experienced at the time of the donation.

A control solution was also collected, in the form of saline trickled down the cheeks of the donor women.

Both the tears and the saline solution was flash-frozen in liquid nitrogen before being thawed for use in a controlled experiment.

During the experiment, a group of 31 healthy men repeatedly sniffed a glass jar containing either 1ml of tears or 1ml of saline solution.

The participants then participated in an online video game against a fictitious opponent who they were told was a real person.

The game contained acts of provocation, where money was taken from the participant, and revenge events, where the participant could deduct money from his opponent at no personal gain.

The study authors from Weizmann Institute of Science in Israel and Duke University Medical Center in the US observed a 43.7% reduction in aggression among participants following exposure to tears.

A similar effect – where female tears dampen male aggression – has previously been reported in rodents.

“We suggest that tears are a mammalian-wide mechanism that provides a chemical blanket protecting against aggression,” the authors noted.