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Sino Biological

Tears dampen arousal

Women's tears contain a chemical signal that reduces men's sexual excitement

By | January 6, 2011

Human tears, once believed to be emotional signals without a biological function, actually contain a chemical that reduces sexual attraction, arousal, and testosterone levels in men, according to a new study published online today (January 6) by linkurl:Science.;http://www.sciencemag.org/
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"It is convincing," said linkurl:Kennedy Wekesa,;http://www.alasu.edu/academics/colleges--departments/science-mathematics--technology/biological-sciences-department/faculty/dr-kennedy-wekesa/index.aspx a biologist at Alabama State University who was not involved in the research. "Given studies of chemosignals in mice, it's not surprising that humans also have chemosignals in bodily fluids such as tears." Previous studies have demonstrated that mouse tears contain chemosignals or pheromones -- excreted chemicals that trigger a behavioral response in other mice, such as aggression in males or acceleration of puberty in females. Yet human tears were long thought to serve simply as an emotional signal -- a communication trait unique to our species. But three years ago, while testing the effect of tears on mood in people, linkurl:Noam Sobel;http://www.weizmann.ac.il/neurobiology/worg/ and colleagues at the Weizmann Institute of Science in Israel made a surprising observation. Male subjects exposed to emotional tears -- isolated from females crying during sad movies then deposited onto a small pad pasted above the male's upper lip -- felt no difference in happiness or sadness, but they did experience a change in another emotion: According to a questionnaire the subjects completed, "there was a pronounced drop in sexual arousal," Sobel told The Scientist. "That's what started us off looking more carefully in that direction." In a subsequent 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. "This is the chemical word for 'No,'" said Sobel. "Or at least for 'Not now.'" Sobel speculates, however, 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," he said. "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." Overall, the study "raises lots of interesting questions," added Wekesa. Are there chemosignals in tears of joy or eye-protective tears (produced by cutting onions, for example)? Also, how might men react to the tears of other men, rather than women? The researchers studied only women's tears out of necessity, said Sobel: The only good criers who volunteered for the study were women. Still, "we don't think this is something unique for women," said Sobel. "I would predict, without hesitation, that there will be chemosignals in men's tears and in children's tears, and these chemosignals will all act within, as well as across, gender." Gelstein, S., et al., "Human tears contain a chemosignal," Science, doi: 10.1126/science.1198331
**__Related stories:__***linkurl:Gut bugs affect mating;http://www.the-scientist.com/news/display/57793/
[1st November 2010] *linkurl:New role for pheromones?;http://www.the-scientist.com/blog/display/56056/
[14th October 2009] *linkurl:Sexual communication in tears;http://www.the-scientist.com/news/20051006/01/
[6th October 2005]
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Comments

Avatar of: jeffrey thatcher

jeffrey thatcher

Posts: 2

January 6, 2011

I didn't read the full article but shouldn't the authors have used "non-emotional" tears as a control group? This would show that the tears of the women in the test group contained different pheromones when they were sad.
Avatar of: Richard Patrock

Richard Patrock

Posts: 52

January 6, 2011

I want to get in on this product. The ad for 'abstinence only' will say, Keep him at bay naturally. Let the tears keep the tears away!
Avatar of: Bruce Livett

Bruce Livett

Posts: 1

January 6, 2011

Is there a difference in quality (pheromones) between the real thing and pretend? Would be interesting to find out.
Avatar of: Mavi Gozler

Mavi Gozler

Posts: 2

January 7, 2011

I don't have paid access to the article, but the abstract suggests a hypothetical chemosignal with no molecular identification and characterization of any potential signals. This being Science journal, I suspect the studies on effect (not cause) were rigorously controlled, but I will be much less skeptical once the single substance (or combination of substances?) is identified as having the causative effect. Once identified, the potential for use and abuse will be forthcoming, and then the need to develop counteracting agents will follow.
Avatar of: jeffrey thatcher

jeffrey thatcher

Posts: 2

January 7, 2011

After reading 1984 it seems that a product made from these pheromones might just be one of Orwell's prophecies ;-).\n\nDown w/ big brother!
Avatar of: ann watson

ann watson

Posts: 1

January 7, 2011

I have large and small dogs. It's been my observation, not only with my own dogs, but with other dogs also, that many small dog's eyes are constantly draining tears. In small white dogs it creates an(to us humans)unsightly stain on their fur. Reading this paper makes me wonder if it isn't a defensive mechanism to turn off the natural aggression of larger dogs toward them. If you go to a dog park, you'll find large and small dogs playing together happily with no danger to the small dogs.
Avatar of: JAMES KOHL

JAMES KOHL

Posts: 53

January 10, 2011

http://www.ncbi.nlm.nih.gov/pubmed/9699878 "Modulation of serum testosterone and autonomic function through stimulation of the male human vomeronasal organ (VNO) with pregna-4,20-diene-3,6-dione" This group claimed that the modulation of testosterone occurred via what turned out to be a non-functional human VNO. Despite the inacurate depiction of the mechanism involved, a conserved neurophysiological mechanism in mammals allows olfactory/pheromonal input to modulate gonadotropin releasing hormone, luteinizing hormone/follicle stimulating hormone ratios, and levels of steroids like testosterone. If pheromones in the tears of mice do this, is it not obvious that human pheromones have similar effects on physiology (and on behavior)?
Avatar of: Mike Waldrep

Mike Waldrep

Posts: 155

January 18, 2011

Interesting! I hope that everyone hd a nice Martin Luther King,Jr.Day!
Avatar of: Mike Waldrep

Mike Waldrep

Posts: 155

January 18, 2011

Interesting! I hope that everyone had a nice Martin Luther King,Jr.Day! Sorry about the typo.
Avatar of: anonymous poster

anonymous poster

Posts: 69

January 18, 2011

When the influence of social conditioning is large, many of these studies may be self-regulated in some manner so as to vitiate the conclusions. If there is any truth in it, it would be difficult to understand one major outcome of any war...gross abuse of women! There happen to be a few million carrying the Y-chromosome of Genghis Khan. I cannot imagine there would an insignificant number of women crying in any war. \nIf lowered testosterone levels is all that matters for hypotheses like this, a swift kick, you know where, may produce biologically more robust, incontrovertible results. Time will tell.

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