A chemical signal in human female tears lowers aggression in males.
Level 3 - non-randomized controlled study
Controlled laboratory experimental and neuroimaging study in humans alongside in vitro assays.
PubMed 38127837 · doi:10.1371/journal.pbio.3002442
What was done
Researchers tested whether sniffing human emotional tears reduces male aggressive behavior using a standard laboratory behavioral aggression paradigm. To evaluate peripheral olfactory mechanisms, tears were applied to 62 human olfactory receptors in vitro. Central neural mechanisms were investigated by repeating the behavioral experiment during functional brain imaging (fMRI).
What was found
Sniffing emotional tears without an odor percept reduced human male aggression by 43.7%. Four olfactory receptors responded to tears in a dose-dependent manner. Functional brain imaging showed increased functional connectivity between olfactory and aggression brain substrates alongside reduced overall neural activity in aggression-related networks.
Why it matters
This study provides evidence that human tears contain an odorless chemosignal capable of dampening aggressive behavior and modulating aggression-related brain circuitry, suggesting a conserved mammalian social chemosignaling mechanism.
Limits
The abstract does not state the sample size (n), participant demographics, control substance details, or exact statistical metrics beyond the percentage decrease. The findings are restricted to human male behavioral responses to female tears in an artificial laboratory task.
Cited by
- supports Scientific research shows that human tears affect hormone levels in people around them.