Well, here is a tear-jerker if I’ve ever seen one, published in the January 6 issue of Science Online.
Professor Noam Sobel and his colleagues of the Weizmann Institute of Science in Israel asked a simple, yet profound question: why do people cry? The prevailing belief was that crying transmits a message –I am distressed, or sad, or hurting; and sometimes: I am overwhelmed with joy. In other words, tears are emotional signals, but they don’t have any biological effect –or so we thought. And for a good reason; experiments in mice showed that their tears contain pheromones, or chemical signals, that create a behavioral response in other mice – aggression in males and acceleration of puberty in young females. Alas, we human males could cry our hearts out with no similar effect on our own young females. So, the self-congratulatory conclusion was that we are unique; we are the only species that uses tears for purely emotional reasons, without any intent of manipulating behavior of others. Very noble, but is it right?
The Sobel experiment
About three years ago the Weizmann investigators wanted to find out if there are pheromones in human tears that affect mood. For that they needed some “good criers” in order to accumulate enough material for chemical analysis. And what a surprise: they couldn’t find “good” lacrimose Israeli men. From among the crying females they selected three who shed copious tears while watching tear-jerker movies (as an aside, I’d hate to go to the movies with these ladies). When they dripped the tears onto a pad and then pasted them on the subjects’ upper lips, they found that the men felt no difference in happiness or sadness (“frankly, my dear, I don’t give a damn”), but they did experience a change in another emotion: sexual arousal plummeted to unfathomable depths. Surprise! and totally counter-intuitive.
The urge to drill deeper into this unexpected observation led to the present study.In this study, the researchers measured heart and respiration rates, skin temperature, testosterone levels and brain activity of sexual-arousal-related brain structures, in response to sniffing emotional tears, which are odorless and clear. Saline was used as a control. They recorded an overall reduction in all measures, leading the researchers to a central conclusion: Women’s emotional tears contain a signal that reduces men’s sexual excitement. As Sobel commented, ‘This is a chemical way of saying “no”, or at least “not now”.’
Which raises an interesting question: why not just say “no”? after all, we are endowed with the gift of speech. There must be more to it. Indeed, Sobel speculates that the results may be part of a larger picture related to aggression, since lowered testosterone is also linked to lowered aggression in males. “It could be that what we measured — sexual arousal — is a byproduct of lowering aggression. It’s easy to come up with an evolutionary reason for why it would be helpful to have a signal that lowers one’s aggression toward you.”
Questions raised by this study
- Only female emotional tears were tested. Would male tears have the same effect on females?
- What about an intra-gender effect, as in female tears on females, or male tears on males?
- What about tears of joy?
- What about protective tears, like the ones induced by cutting onions?
- What about babies’ tears?
Now, let your mind wander. What if the active ingredient in tears is isolated and synthesized? Can you see the potential in using it as a spray against aggressive males, turning them into docile poodles? Coming to think of it, this could be the ultimate chemical warfare weapon; Ahmadinejad, here we come.
Sorry, just daydreaming.