Friday, January 7, 2011

The Power of a Woman's Tears

First off a big thanks to Kurt Harris over at PaNu for his props for my blog (at the same time he recommended Andrew's) - glad to see you back into blogging, and Professor Gumby is certainly a fascinating fellow.  A bit more housecleaning - there are a couple new studies out about Alzheimer's and Mild Cognitive Impairment and ketosis that I want to cover, and I'll probably get to that this weekend.  However, this morning into my mailbox tumbled a new study that has "Evolutionary Psychiatry" written all over it (or maybe not, but it is cool nevertheless), "Human Tears Contain a Chemosignal"  from pretty much the premier academic science journal in the world, Science (actually this one is in Science Express, which is the advanced online publication arm of Science.) 

The paper starts out with Charles Darwin, and that's always a good sign.  Basically the evolutionary question is why do we cry?  It builds on nicely from yesterday's post on sex.  Emotions are troublesome, after all.  While some (like love) are typically sweet and enjoyable, others (like grief) are just plain painful.  We really don't have much choice about feeling them - if you somehow suppress anger or grief, for example, it usually pops out in other unhealthy ways, such as anxiety, substance abuse, or irritability.  Take it from a psychiatrist - the best thing to do with your powerful, driving emotions is to feel them and to act on what they are telling you in a reasonable way (that would not usually include busting a beer bottle over someone's head when you are angry).  For example, I'm still pretty angry about what I consider the misappropriation of medical and nutritional "science" to peddle cheap commodity grains at the expense of our health.  Each time I read Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health (Vintage), it gets thrown across the room a few times.  So I write a blog, and I promote the blogs of like-minded folks to the right.  Not because many of them also have me on their blogrolls, but because I like how they put their minds to the real problem of nutrition, lifestyle, and health in the 21st century, and I inevitably learn something from them.

But back to the paper.  These researchers started out small.  They took the tears of two women, ages 30 and 31, who watched sad movies in isolation.  They also took a vial of saline that had been trickled over the skin of the women and let each of 24 young men (mean age 28) have a sniff - the men couldn't tell a difference in smell between the emotional tears and the saline.  Then another 24 men (mean age 27) smelled the tears of three women (mean age 30) or saline and filled out some rating scales about the experience. 

Then the young men were given a pad pasted to their upper lip with 100 microliters of tears or saline dribbled onto the pad.  While thus anointed, the young men were asked to rate picture's of women's faces for sadness and how sexually attractive the faces were, and men were given a standard questionnaire to assess empathy.  Each subject (in double blind fashion, and on different days) did the tests both with a saline and tear-stained pad. Tears or saline didn't change the men's empathy ratings or their ratings of sadness on the women's faces, but 17 out of 24 men smelling tears found the women's faces to be less sexually attractive (p <0.02).

The researchers at this point brought in 50 men and used a sensory paradigm to generate negative emotions, all the while measuring heart rate, sweating, respiration rate, skin temperature, and self-rating of mood and arousal.  Salivary levels of testosterone were also measured before, during, and after smelling the tears or trickled saline of 5 donor women.  After sniffing, the subjects watched sad movies (one of the news reports mentioned Terms of Endearment). Once again, the subjective arousal of tear-sniffing men was decreased, as was the level of arousal in general measured by sweating, respiration, etc., and, more tellingly, the levels of testosterone in saliva dropped.

Then the researchers got very cute (and this last bit is likely why the paper made it into Science).  They took 16 young men with saline or tear-stained nose pads and had them watch sexually arousing movies and view sexy pictures - then stuck them into fMRIs.  The sexual arousal signal apparently is visible in the hypothalamus and left fusiform gyrus of the brain, and within these regions, activity was significantly lower in men who were sniffing tears.

All in all, ladies, if you are looking to dampen the mood, take him to a tear-jerker.  Otherwise, maybe stick with an action film or comedy.  Also, tears may be a quick way to diffuse a man's overall emotional arousal - it may be an ancient hormonal way to tell an aggressive man to back off.

Now other animals also have tears, though it is thought humans are the only ones to shed emotional tears.  In any event, the lacrimal secretions of mice contain chemosignals, as do human urine and sweat.  Chemosignals in mammalian studies have uncovered pheromones that increase receptive sexual behavior or decrease arousal as in this study, while other chemosignals trigger sexual maturation or provide information (such as kinship - this may be why women will tend to be most attracted to men who have the most different major histocompatibility genes).

I'll let the researchers finish up:

The findings pose many questions: What is the identity of the active compound/s in tears?...Moreover, could the emotional or hormonal state (menstrual phase, oral contraceptives) of the crier/experimenter influence the outcome?  In turn, what if any are the signals in men's tears... children's tears, and what are the effects of all these within rather than across gender?

 My question is - what are we doing to our behaviors by masking scents with bathing, deodorant, and perfume?   Would I be a more perceptive psychiatrist if my patients stopped bathing?  Hmmm.

14 comments:

  1. I agree that the researchers bring up some interesting questions. What are the differences (if any) between emotional tears of sorrow vs tears of pain vs tears of joy. I'm guessing it's hard to to get a worthwhile volume of tears of joy! What about the tears of crazy teen girls when they see Justin Bieber?

    I've also wondered about how personal hygiene plays into attraction, though I generally contemplate how we tend to chose to wear fragrances that we enjoy (or at least I do, I assume this is generally the case), yet it seems that in studies that have looked at the attraction of scent, we tend to prefer scents of people that are genetically different than us. Are we therefore dressing ourselves up to smell like the person we in fact would be most (genetically) compatible with? If so, are we then repelling those who might be the best fit? Probably totally over analyzing this, but I find it fun to think about!

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  2. According to the press coverage, the tears had to be less than 2 hours old, so they had the women on call to come in and watch some movies and cry to have a constant fresh supply.

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  3. Dr. Deans, thank you very much for this post and for your blog. It is always a delight to come here and read.

    This is one of the those subjects that is so large, it is a challenge to know what to address first. I shall address the simplest aspects of the subject, which come to mind at this time, in this comment.

    It would be interesting to compare those who keep a Paleo diet and do not use petro-chemical fragrances with those who eat the SAD and use the petro-chemical fragrances.

    I lived in Europe for many years and often heard that the use of artificial smells covered up who a person was. One couple told me that part of their process of finding out if they fit together was to not use petro-chemical fragrances.

    The toxic effects of the fragrances in commercial cleaning products and toiletries is an immense problem. I can well imagine that some of those who come to your office are there due to the effects of what is in their laundry detergent, air freshener, hand lotions, antiperspirant, dishwashing liquid, dryer sheets, etc. I wonder how many ailments there have been since the advent of detergents.

    There is nothing as nice as homemade soaps and the smell of laundry hung in the sun. Nothing from a chemical factory could come close.

    Also, there is something very attractive about people who do not feel they need to hide who they are behind all those artificial smells.


    Thank you again for your blog. I always look forward to your posts.

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  4. I have had a different experience with womens' tears. I used to supervise many women most of them expressed their anger with tears. Whereas men would raise their voice or shout when they got angry women would start crying.

    My reaction to their crying soon got to be: hand them Kleenexes, wait them out until they stopped crying and then continue the discussion as if nothing happened. It seemed to work.

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  5. Hmm.... As a broke graduate student I donate blood for research (and $$) as frequently as they'll allow. Haven't seen any requests for tear donors, but I'll be on the look out! There are people looking for bone marrow donors for research, but I'm not willing to take that leap for extra beer money.

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  6. Crying is a way for children to appear non-threatening during a confrontation. Tears in their eyes impair their ability to see. Therefore, crying impairs their ability to fight as they can't see clearly. Crying is a way for children to avoid confrontation from older, stronger people.

    Crying is a sign of submission. Because tears impair a person's ability to fight, crying means that a person resigns from the fight and is willing to submit to the winner.

    Women are less risk-taking than men. So they are more protective and cautious than men. Women cry more than men because they are more protective and less willing to risk confrontation.

    Also, tears may be a quick way to diffuse a man's overall emotional arousal - it may be an ancient hormonal way to tell an aggressive man to back off.

    What do you mean? The experimenters didn't give out samples of tears from children and men. So I don't know if it's women-specific.

    I've seen a study which has found that men who have babies have lower testosterone than men who didn't have any children. Was it caused by the tears of the baby?

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  7. The data we have is the data we have - I'm happy to see men cry too.

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  8. There's the studies which I'm talking about:

    http://www.news.harvard.edu/gazette/2002/09.19/01-testosterone.html
    http://www.news.wisc.edu/15550

    Lowered testosterone decreases sex drive. I bet it's because, as I quote from the article "Lower levels of testosterone may increase the likelihood that men will stay home and care for their wives and kids, while decreasing the likelihood they will go out drinking with the guys and chase other women."

    If they took tears form a baby rather than a woman, I hypothesize that they will have the same arousal-decreasing effect.

    Evolutionary psychology is a VERY INTERESTING TOPIC. But it's covered with tons of false assertions such as the belief that there's an "alpha male," the belief that women like high status men because they "can provide more resources for their child," the "testosterone indicator" myth, the belief that "humor is a sexual ornament," the belief that "men are attracted to high-status women" (although disproven by Matt Ridley in the later chapters of his book), and the belief that women like "soft" men during their non-fertile phases of their cycle. I have found holes in each one of those assertions.

    Famous evolutionary psychologists, by themselves, develop nonsensical theories. Yes, this includes Richard Dawkins, Matt Ridley, Geoffrey Miller, and Stephen Pinker.

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  9. Yes, I agree that evolutionary psychology can be exceedingly irritating.

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  10. Yeah, but it is also FUN.

    I just love the notion of altruism vs reciprocal altruism.

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  11. Leon, it's "fun" if you're not in a class of oppressed people, like women, who have to deal with the fallout from these sorts of beliefs. Check your male privilege.

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  12. Star Trek was right again!! Episode 68 Original Star Trek. Of course on the planet Elas the biochemistry differs.

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  13. You forgot the other power of tears. When a woman cries, she can get help and support from anyone anywhere among the chivalrous white knights in the world. This is true in valid situations and also in situations where she wants to abuse her husband or lover and commit violence by proxy. For example if she is divorcing her husband and wants custody of the children, all she has to do is fake tears. If she accuses him to the police wrongly, and the police are in the man's own house, and she cries these tears, then they are on him like black tar. If he is a victim of abuse, and she cries in order to reverse the victim status, it will elicit sympathy. I have heard that women have bigger tear glands and narrower ducts, which make it easier for them to cry and more likely, and men have smaller glands and bigger ducts. Therefore, women can elicit sympathy and direct other people's behavior if it is based on good will. This is a true power and with all power comes responsibility and the possibility of abuse. This is certainly an evolutionary facet of tears I am sure. No I have not experienced this myself and am not bitter, but I have witnessed other men as victims of this and I observe the condition of things in society. This would be interesting to look into, in group psychology in evolutionary history in our hunter gatherer times, I guess.

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  14. Hmmm... Women’s tears decrease male sexual arousal. Could this be a defense against rape? Those sneaky females! Women’s tears decrease male general arousal. Could this possibly decrease the severity of the physical or mental beating? Again, *sneaky*. Those poor ignorant ape-men.

    But now we can in good conscience ignore women’s tears, now that we know they don’t mean anything is *really* wrong.

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