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Human tears: Is it a natural antidote to male aggression?

HQ team

January 1, 2024: A new study done by the Weizmann Institute of Science in Israel looks into how human female tears reduce male aggression by altering aggression-related brain networks.

Sniffing the chemical signals present in tears, akin to those observed in rodents, suggests a unique protective function associated with the chemicals present in tears.

Charles Darwin was curious about the purpose of human tears and now researchers have tried to unravel the signaling behind the onset of such tears. The tears of female mice, for example, contain signals that mitigate intermale aggression by influencing the males’ aggression-related brain networks. Similarly, subordinate male blind mole rats utilize tears to diminish dominant male aggression towards them.

The lead and co-corresponding author of the study, Shani Agron, explains the rationale behind focusing on male subjects: “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.”


While human tear chemosignaling has limited evidence, a previous study by some of the researchers involved in the current study revealed that women’s tears contain an odorless chemical signal. When males sniffed this signal, it led to a reduction in self-rated sexual arousal, physiological arousal, and testosterone levels.

The experiments involved collecting ’emotional’ tears from six female donors and assessing their impact on 25 male participants playing an aggressive monetary game. The participants, unaware of whether they were exposed to tears or a saline solution, exhibited a notable 43.7% reduction in aggression when exposed to tears. Statistical analysis indicated a mere 2.9% probability of obtaining this outcome by chance, reinforcing the notion that chemosignals in human emotional tears play a pivotal role in blocking aggression.

Aggression reducing effect

Furthermore, functional magnetic resonance imaging (fMRI) scans revealed reduced activity in brain structures associated with aggression, specifically the left anterior insula cortex (AIC) and bilateral prefrontal cortex (PFC), after exposure to tears. The study delved into the brain’s functional connectivity, identifying increased connectivity between the left AIC and the right amygdala and piriform cortex, both implicated in olfaction (smelling) and aggression.

Noam Sobel, another corresponding author of the study, highlights the broader implications of these findings: “We’ve shown that tears activate olfactory receptors and that they alter aggression-related brain circuits, significantly reducing aggressive behavior. 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.”

The study, published in the journal PLOS Biology, opens up avenues for further exploration, extending the study to include women and gaining a comprehensive understanding of the impact of tears on both genders.

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