Inhaling the Scent of Women’s Tears Reduces Male Aggression by 44%

A captivating study discovered that the inhalation of female tears significantly diminished male aggression and lowered activity in brain networks associated with aggression. The effect, attributed to chemical signals in tears and observed in rodents as well, is proposed to have a protective function.

Charles Darwin found emotional tears perplexing, attributing their purpose solely to eye lubrication. While emotional tears were initially considered a uniquely human trait, subsequent research has revealed that mammalian tears contain chemicals that function as social signals, with one such signal being the reduction of aggression.

For instance, female mice’s tears include signals that suppress intermale aggression by dampening activity in the males’ aggression-related brain networks. Additionally, subordinate male blind mole rats use tears to decrease aggression from dominant males. Researchers from the Weizmann Institute of Science in Israel have conducted experiments to explore whether, akin to rodents, inhaling human female tears diminishes aggression in men and its functional impact on their brains.

Unveiling the Impact of Tears on Male Aggression

“We were aware that sniffing tears lowers testosterone, and since lowering testosterone has a more pronounced effect on male aggression, we initially focused on studying the impact of tears on men to increase the likelihood of observing an effect,” stated Shani Agron, the study’s lead and co-corresponding author. Although there is limited evidence of human tear chemosignaling, a prior study by some of the researchers found that women’s tears contain an odorless chemical signal. When males sniffed this signal, it led to reduced self-rated sexual arousal, physiological arousal, and testosterone levels.

To investigate the impact of sniffing female tears on aggression in men, the researchers collected ’emotional’ tears from six donors who, after watching sad film clips in isolation, experienced crying. Twenty-five men then played a two-person monetary game, thinking their opponent was human but was actually a computer algorithm. The game was designed to provoke an aggressive response from the male, who believed their opponent was cheating. If given the chance, the male could retaliate against the opponent, causing them to lose money with no personal gain.

Tears as Aggression Inhibitors

Before engaging in the game, the participants were exposed to either female tears or a saline solution, both of which are odorless. The individuals were not informed about what they were sniffing. The researchers observed a significant 43.7% decrease in aggression following exposure to tears. To assess the robustness of their findings, they conducted a bootstrap analysis, a statistical procedure that generates numerous simulated samples by resampling a single dataset. The analysis indicated a 2.9% probability of obtaining these results by chance, suggesting that, similar to rodents, chemosignals in human emotional tears primarily serve an aggression-blocking function.

Subsequently, the researchers investigated the impact of sniffing tears on the participants’ brains. While engaging in the monetary game, 26 male participants underwent a functional magnetic resonance imaging (fMRI) scan after exposure to tears or saline. In two brain structures associated with aggression – the left anterior insula cortex (AIC) and bilateral prefrontal cortex (PFC) – the researchers observed reduced activity following exposure to tears. There was a significant correlation between the experimental condition (tears versus saline) and activity in these regions.

In exploring the brain’s functional connectivity, the researchers discovered that tears specifically influenced the left anterior insula cortex (AIC), exhibiting significantly increased connectivity with the right amygdala and piriform cortex. These regions, sharing structural connectivity, are part of a functional network associated with olfaction (smelling) and aggression.

Exploring the Role in Reducing Aggressive Behavior

“We have demonstrated that tears activate olfactory receptors and modify aggression-related brain circuits, leading to a significant reduction in aggressive behavior,” noted Noam Sobel, another corresponding author of the study. “These findings suggest that tears act as a chemical shield, providing protection against aggression – a phenomenon common to both rodents and humans, and potentially to other mammals as well.”

In a separate study in 2022, researchers observed a significant increase in dogs’ tear volume when they were reunited with their owner, indicating the possibility of emotional – happy – tears. However, additional research is necessary to determine whether these tears contain chemosignals detectable by other dogs or humans.

After establishing the impact of sniffing tears on men’s behavior, the researchers aim to broaden their research scope.

“During our search for volunteers willing to donate tears, we mostly found women, as it is more socially acceptable for them to cry,” explained Agron. “However, it is crucial to extend this research to include women to gain a more comprehensive understanding of this impact.”

Read the original article on: New atlas

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