London, Dec 24 (IANS): Sniffing women’s tears lowers brain activity related to aggression in men, reducing aggressive behaviour, researchers have discovered.

The Weizmann Institute of Science in Israel conducted the study, which discovered that human tears include a chemical signal that decreases activity in two aggression-related brain regions.

In the study, published in the journal PLOS Biology. In the study, researchers, led by PhD student Shani Agron from the institute's Brain Science Lab, set out to determine whether tears have the same aggression-blocking effect in people as they do in rodents.

In a series of experiments, men were exposed to either women’s emotional tears or saline, without knowing what they were sniffing or being able to distinguish between the two.

Following that, they played a two-player game designed to generate hostile behaviour in one player towards the other, who was portrayed as cheating.

When given the opportunity, the men could get revenge on the perceived cheaters by causing them to lose money, though they themselves gained nothing.

After sniffing women's emotional tears, the men's revenge seeking aggressive behaviour throughout the game decreased by 44 per cent, or roughly in half, the researchers noted.

The researchers mentioned that this result seemed equivalent to the effect observed in rodents, but rodents have a structure in their noses called the vomeronasal organ that picks up social chemical signals.

"These findings suggest that tears are a chemical blanket offering protection against aggression – and that this effect is common to rodents and humans, and perhaps to other mammals as well," said Prof Noam Sobel, head of the Brain Sciences Department.

Agron said: "We knew that sniffing tears lowers testosterone, and that lowering testosterone has a greater effect on aggression in men than in women, so we began by studying the impact of tears on men because this gave us higher chances of seeing an effect."