Emotional Tears in Humans and Animals: Scientists have previously discovered that tears in several mammals, including humans, contain chemicals that act as social signals, suggesting a potential link between tears and emotional expression. Recent experiments focused on male aggression revealed a surprising connection between human tears and the inhibition of aggressive behavior.
The Tear Experiment: In a series of experiments, men were exposed to the scent of women's tears or a saline solution (odorless control) before engaging in a two-player aggression-inducing game. The participants were led to believe that the other player was cheating, providing an opportunity for revenge. Those who sniffed tears exhibited a remarkable 44 percent drop in aggressive behavior compared to the control group.
Olfactory Receptors and Brain Activity: Further investigations into olfactory receptors revealed that, out of 62 participants, four had receptors activated by tears. MRI scans of men exposed to tears showed less activity in aggression-related brain regions – the prefrontal cortex and anterior insula – during the aggressive game.
Human Tears as Chemical Signals: The researchers concluded that human tears contain a chemical signal, akin to findings in mice, which acts as a deterrent to conspecific male aggression. This challenges the notion that emotional tears are exclusive to humans, as the protective effect against aggression appears to be a shared trait across species.
Beyond Aggression: Effects of Tears: While protection against aggression is a highlighted effect, researchers believe tears may have additional impacts yet to be fully understood. Recent studies also suggest that animals, including dogs, might exhibit emotional tears, broadening the scope of tear-related effects beyond aggression.
The Gendered Aspect of Tears: The study, focusing on men exposed to women's tears, notes that the cultural acceptance of women crying made it easier to find volunteers. However, the researchers speculate that the effects of tears are related to caregiving instincts, particularly in close-range interactions.
Expanding Understanding of Tear Effects: The researchers emphasize the need to explore the effects of tears beyond male aggression. They propose that chemosensing of tears is a plausible aspect of human behavior, particularly in close relationships. Additionally, the study speculates that tear-related effects might be consistent across genders and become ecologically relevant in scenarios involving infant tears, where chemosignals could play a crucial role in communication.