It is a proven fact that tears of mice contain “chemosignals,” which are also called “pheromones.” In a study conducted in Israel, researchers examined whether human tears also have similar components as that of mice. The researchers found that when men merely sniffed negative-emotion-related odorless tears of women participants, they experienced a reduction in sexual appeal when looking at pictures of women’s faces. Moreover, after sniffing such tears, men experienced reduced self-rated sexual arousal, reduced physiological measures of arousal and reduced levels of testosterone.
Tears primarily function to protect our eyes from microbes and dust in the surroundings. Until now, the functional significance of emotional tears was not known. Some studies have shown that the composition of tears produced when something irritates the eyes is different from the composition of tears produced during an episode of negative emotions. The researchers in the present study hypothesized that negative-emotion-related tears do have some chemosignaling properties. They compared various emotional changes, testosterone levels and brain MRI activity changes after inhaling negative-emotion-related tears and after inhaling saline.
* Two women were asked to watch a sad movie and were asked to collect their tears.
* 24 men of a mean age of 27 years were first asked to sniff freshly collected tears. They were shown two photographs and were asked to rate the sadness and sexual attraction. The following day, the experiment was repeated using saline instead of tears.
* In the second part of study, psychophysiological arousal, salivary testosterone levels and a brain MRI were studied in 50 men before, during and after sniffing the tears.
* Ratings of sadness in photographs were not significantly different after sniffing tears or saline. “But rather a shift in sexual attraction attributed to the faces, whereby the faces appeared less sexually attractive after sniffing tears than after sniffing saline for 17 of the 24 participants,” per the study authors.
* In the second part of the experiment, during sniffing of tears, there was an increase of galvanic skin response, which is an important component of psychophysiological arousal.
* Compared to the baseline (151.96 pg/ml), the levels of salivary testosterone were markedly reduced (132.66 pg/ml) after sniffing tears.
* MRI imaging of the brain showed noticeably reduced activity in the hypothalamus and the left fusiform gyrus, which are involved in sexual arousal.
The present study has highlighted the sexual disinterest produced by negative-emotion-related tears. Further studies are necessary to assess other emotional effects produced by tears. It is necessary to isolate the compound involved in chemosignaling. It is also necessary to study the influence of emotional or hormonal status of the crier or the experimenter. In the present study, only signals produced by tears of women were studied. Future studies need to study the signals present in tears of children or men.
This is the first study which has identified the emotional function of tears. It is proven in the study that tears can produce emotional changes in men by their chemosignaling property. None of the men actually saw women crying, they just sniffed the tears that were collected from donors. As it was a blind study, participants did not even know which fluid they were sniffing. A decline in testosterone levels before and after sniffing tears indicates a reduction in sexual arousal in men. In the U.S., when someone hugs a crying person, their nose comes very close to the crier’s teary cheeks. Because of this, there is a pronounced inhalation of tears that probably produces much more of an emotional effect than those examined in the present study.
For More Information:
Human Tears Contain a Chemical Signal
Publication Journal: Science, January 2011
By Shani Gelstein; Yaara Yeshurun; Weizmann Institute of Science, Rehovot, Israel