Men perceive women in red as more sexually receptive. Do women as well?

Credit: Image courtesy of Society for Personality and Social Psychology

The picture was used for the color manipulation in Experiments 1 and 2

(the face of the female target was intact in the experiment but is blurred

here to protect privacy). The dress color was red or white.

As I've written in earlier posts, I've been a man for most of my life, as least since the age of 25 or so.  I'd never heard of this "wearing red is a sexual signal" thing.  Really? 

Well. 

Hmmm.

Anyway, I can see how an author knowing of this common perception can influence a piece of fiction as a way for a woman character to let "him" know she's interested. 

What the researchers are examining in this study is do women see other women who happen to be wearing red as a threat to their relationship.  It's this sort of detail that helps a story succeed.  While you read this, I'm headed to Piggly Wiggly to look for women wearing red.

If I come back with a black eye, you'll understand.


Women are more likely to wear a red shirt when they expect to meet an attractive man, relative to an unattractive man or a woman. But do women view other women in red as being more sexually receptive? And would that result in a woman guarding her mate against a woman in red? A study has sought to answer these questions.

Perceptions of Sexual Receptivity
Nonverbal communication via body language, facial expressions and clothing conveys information to others, occasionally with unintended social consequences. Researchers from the University of Rochester, Trnava University, and the Slovak Academy of Sciences collaborated to study what information the color red conveys to women.

Three experiments were involved in the study. The first experiment asked individuals to compare a digital image of a woman wearing red versus a woman wearing white. Participants were asked questions about the woman's sexual receptivity, such as "This person is interested in sex," which required moving a bar along a sliding scale from "No, not at all" to "Yes, definitely." Participants rated the woman in red as more sexually receptive than the woman in white. Sixty-nine percent of participants reported they were in a committed relationship, and the results of the experiment showed that participant's relationship status did not have a significant effect on their perceptions of women in white versus red.

Derogation and Mate-Guarding
The researchers tested whether participants would derogate a woman in red and the likelihood of guarding their mate from a woman in red in subsequent experiments. "Derogation [involves] speaking poorly of another person to make them seem inferior, undesirable, or unlikeable, while making oneself seem superior and more likable by contrast," lead researcher Adam Pazda explains. "Mate-guarding is the act of protecting one's own romantic partner from romantic or sexual encounters with others." The researchers specifically tested whether women would derogate on the topics of fidelity ("I would guess that this women cheats on men"), and financial resources ("I would guess that this woman has no money").



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The third and final experiment altered the conditions slightly. Instead of comparing white and red, the researchers chose to compare green and red in an effort to eliminate the possible bias of associating white and purity. "Using green allowed us to equate both hues on lightness and chroma, which allowed for a more rigorous, controlled test of the red effect," Pazda said. The participants were located in an Eastern European country, rather than the U.S. as in the two prior experiments. To determine intent to mate-guard, participants were asked: "How likely would you be to introduce this person to your boyfriend?" and "How likely would you be to let your boyfriend spend time alone with this person?"

Results from the last two experiments confirmed that women found another woman in red to be more sexually receptive, versus white or green. In terms of derogation, participants who viewed a woman in red were more likely to derogate the woman's sexual fidelity, but not financial resources. Participants did not show any difference between sexual fidelity derogation and financial resource derogation in relation to a woman in white. Women were more likely to guard their partner from a woman dressed in red if they are in a committed relationship, relative to a woman in green.

 *  *  *  *  *

Story Source:  Materials provided by Society for Personality and Social Psychology.  Adam Pazda et al. Viewing Another Woman in Red Increases Perceptions of Sexual Receptivity, Derogation, and Intentions to Mate-Guard. Personality and Social Psychology Bulletin, July 2014

Attention writers: Sitting too much stifles creativity, harms your cardiovascular health

Hemingway stood while writing.  So many others walked to

think through story lines, literally writing in their minds before

heading back to their desks to put it on paper.  Now science

reveals that writing while walking is more creative and healthier.

Cardiologists have found that sedentary behaviors lowers cardiorespiratory fitness levels. New evidence suggests that two hours of sedentary behavior can be just as harmful as 20 minutes of exercise is beneficial.
 
The study, published in today's online edition of Mayo Clinic Proceedings, examined the association between fitness levels, daily exercise, and sedentary behavior, based on data from 2,223 participants in the National Health and Nutrition Examination Survey (NHANES). Sedentary behavior involves low levels of energy expenditure activities such as sitting, driving, watching television, and reading, among others. The findings suggest that sedentary behavior may be an important determinant of cardiorespiratory fitness, independent of exercise.

"Previous studies have reported that sedentary behavior was associated with an increased risk for cardiovascular outcomes; however, the mechanisms through which this occurs are not completely understood," said Dr. Jarett Berry, Assistant Professor of Internal Medicine and Clinical Science and senior author of the study. "Our data suggest that sedentary behavior may increase risk through an impact on lower fitness levels, and that avoiding sedentary behavior throughout the day may represent an important companion strategy to improve fitness and health, outside of regular exercise activity."

"We also found that when sitting for prolonged periods of time, any movement is good movement, and was also associated with better fitness," said Dr. Jacquelyn Kulinski, a recent graduate from the UT Southwestern Cardiology Fellowship Training Program and first author of the paper. "So if you are stuck at your desk for a while, shift positions frequently, get up and stretch in the middle of a thought, pace while on a phone call, or even fidget."

To stay active and combat sedentary behavior, UT Southwestern preventive cardiologists recommend taking short walks during lunch and throughout the day, using a pedometer to track daily steps, taking the stairs instead of the elevator, hosting walking meetings at work, and replacing a standard desk chair with a fitness ball or even a treadmill desk, if possible.

Taking a walk leads to more creativity than sitting
When the task at hand requires some imagination, taking a walk leads to more creative thinking than sitting, according to research. "Many people anecdotally claim they do their best thinking when walking," said one author. "With this study, we finally may be taking a step or two toward discovering why."

"Many people claim they do their best thinking when walking," said Marily Oppezzo, PhD, of Santa Clara University. "With this study, we finally may be taking a step or two toward discovering why."

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While at Stanford University's Graduate School of Education, Oppezzo and colleague Daniel L. Schwartz, PhD, conducted studies involving 176 people, mostly college students. They found that those who walked instead of sitting or being pushed in a wheelchair consistently gave more creative responses on tests commonly used to measure creative thinking, such as thinking of alternate uses for common objects and coming up with original analogies to capture complex ideas. When asked to solve problems with a single answer, however, the walkers fell slightly behind those who responded while sitting, according to the study published in APA's Journal of Experimental Psychology: Learning, Memory and Cognition.

While previous research has shown that regular aerobic exercise may protect cognitive abilities, these researchers examined whether simply walking could temporarily improve some types of thinking, such as free-flowing thought compared to focused concentration. "Asking someone to take a 30-minute run to improve creativity at work would be an unpopular prescription for many people," Schwartz said. "We wanted to see if a simple walk might lead to more free-flowing thoughts and more creativity."

Of the students tested for creativity while walking, 100 percent came up with more creative ideas in one experiment, while 95 percent, 88 percent and 81 percent of the walker groups in the other experiments had more creative responses after walking compared with when they were sitting.

"Incorporating physical activity into our lives is not only beneficial for our hearts but our brains as well. This research suggests an easy and productive way to weave it into certain work activities," Oppezzo said.

 *  *  *  *  *

Story Sources:

1. Material provided by American Psychological Association (APA).  Marily Oppezzo, Daniel L. Schwartz. Give your ideas some legs: The positive effect of walking on creative thinking.. Journal of Experimental Psychology: Learning, Memory, and Cognition, 2014  
2. Materials provided by UT Southwestern Medical Center. Jacquelyn P. Kulinski, Amit Khera, Colby R. Ayers, Sandeep R. Das, James A. de Lemos, Steven N. Blair, Jarett D. Berry. Association Between Cardiorespiratory Fitness and Accelerometer-Derived Physical Activity and Sedentary Time in the General Population. Mayo Clinic Proceedings, 2014

Science reveals that most people can't handle being alone (writing)

Credit: © gosphotodesign / Fotolia

 

Most people are just not comfortable in their own heads,

according to a new psychological investigation.

Do you like being alone with just your own thoughts for company?  Or to put it another way.  Why do we find it so uncomfortable to be stuck in a room, alone, with only ourselves for company?  Like when you're in your office trying to write your self-assigned 400 words for the day.

 

You're not alone.  Research out of the University of Virginia shows that most people are averse to alone time with nothing to do but think.  We are all, most of us, uncomfortable with nothing to do but think, to the point that study participants gave themselves electric shocks rather than live within their own heads.

 

Interesting results that explain why so many of us find other things to do when we should be writing.  Doing laundry, surfing the interweb, posting to Facebook. Rather that feeling guilty about this, understand that most people respond exactly the same way.  

 

Doing something is better than

doing nothing for most people.

People are focused on the external world and don’t enjoy spending much time alone thinking, according to a new study. The investigation found that most would rather be doing something -- possibly even hurting themselves -- than doing nothing or sitting alone with their thoughts.

Most people are just not comfortable in their own heads, according to a new psychological investigation led by the University of Virginia.

The investigation found that most would rather be doing something -- possibly even hurting themselves -- than doing nothing or sitting alone with their thoughts, said the researchers, whose findings will be published July 4 in the journal Science.

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In a series of 11 studies, U.Va. psychologist Timothy Wilson and colleagues at U.Va. and Harvard University found that study participants from a range of ages generally did not enjoy spending even brief periods of time alone in a room with nothing to do but think, ponder or daydream. The participants, by and large, enjoyed much more doing external activities such as listening to music or using a smartphone. Some even preferred to give themselves mild electric shocks than to think.
"Those of us who enjoy some down time to just think likely find the results of this study surprising -- I certainly do -- but our study participants consistently demonstrated that they would rather have something to do than to have nothing other than their thoughts for even a fairly brief period of time," Wilson said.

The period of time that Wilson and his colleagues asked participants to be alone with their thoughts ranged from six to 15 minutes. Many of the first studies involved college student participants, most of whom reported that this "thinking period" wasn't very enjoyable and that it was hard to concentrate. So Wilson conducted another study with participants from a broad selection of backgrounds, ranging in age from 18 to 77, and found essentially the same results.

"That was surprising -- that even older people did not show any particular fondness for being alone thinking," Wilson said.

He does not necessarily attribute this to the fast pace of modern society, or the prevalence of readily available electronic devices, such as smartphones. Instead, he thinks the devices might be a response to people's desire to always have something to do. In his paper, Wilson notes that broad surveys have shown that people generally prefer not to disengage from the world, and, when they do, they do not particularly enjoy it. Based on these surveys, Americans spent their time watching television, socializing or reading, and actually spent little or no time "relaxing or thinking."

During several of Wilson's experiments, participants were asked to sit alone in an unadorned room at a laboratory with no cell phone, reading materials or writing implements, and to spend six to 15 minutes -- depending on the study -- entertaining themselves with their thoughts. Afterward, they answered questions about how much they enjoyed the experience and if they had difficulty concentrating, among other questions. Most reported they found it difficult to concentrate and that their minds wandered, though nothing was competing for their attention. On average the participants did not enjoy the experience. A similar result was found in further studies when the participants were allowed to spend time alone with their thoughts in their homes.

"We found that about a third admitted that they had 'cheated' at home by engaging in some activity, such as listening to music or using a cell phone, or leaving their chair," Wilson said. "And they didn't enjoy this experience any more at home than at the lab."

An additional experiment randomly assigned participants to spend time with their thoughts or the same amount of time doing an external activity, such as reading or listening to music, but not to communicate with others. Those who did the external activities reported that they enjoyed themselves much more than those asked to just think, that they found it easier to concentrate and that their minds wandered less. The researchers took their studies further. Because most people prefer having something to do rather than just thinking, they then asked, "Would they rather do an unpleasant activity than no activity at all?"

The results show that many would. Participants were given the same circumstances as most of the previous studies, with the added option of also administering a mild electric shock to themselves by pressing a button.

Twelve of 18 men in the study gave themselves at least one electric shock during the study's 15-minute "thinking" period. By comparison, six of 24 females shocked themselves. All of these participants had received a sample of the shock and reported that they would pay to avoid being shocked again.

"What is striking," the investigators write, "is that simply being alone with their own thoughts for 15 minutes was apparently so aversive that it drove many participants to self-administer an electric shock that they had earlier said they would pay to avoid." Wilson and his team note that men tend to seek "sensations" more than women, which may explain why 67 percent of men self-administered shocks to the 25 percent of women who did.

Wilson said that he and his colleagues are still working on the exact reasons why people find it difficult to be alone with their own thoughts. Everyone enjoys daydreaming or fantasizing at times, he said, but these kinds of thinking may be most enjoyable when they happen spontaneously, and are more difficult to do on command.

"The mind is designed to engage with the world," he said. "Even when we are by ourselves, our focus usually is on the outside world. And without training in meditation or thought-control techniques, which still are difficult, most people would prefer to engage in external activities."

*  *  *  *  *
 

Story Source: Materials provided by University of Virginia, written by Fariss Samarrai. 1.T. D. Wilson, D. A. Reinhard, E. C. Westgate, D. T. Gilbert, N. Ellerbeck, C. Hahn, C. L. Brown, A. Shaked. Just think: The challenges of the disengaged mind. Science, 2014.

Orgasms and alcohol influence pillow talk

Credit: © George Dolgikh / Fotolia

 

Orgasms aren't just good for your sexual relationship;

they also promote good communication.

 
Orgasms aren't just good for your sexual relationship; they also promote good communication. Results of a new study published in the latest edition of Communication Monographs reveal that in the aftermath of having experienced an orgasm, people are more likely to share important information with their partners. And, that communication is likely to be positive.

"Post-coital communication is likely linked to sexual and relationship satisfaction," said Amanda Denes, Assistant Professor at the University of Connecticut, and lead author of the study. "For this reason, pillow talk may play a pivotal role in maintaining intimacy."

Oxytocin, a "pro-social" hormone, floods a person's brain immediately after orgasm. Elevated levels of oxytocin are linked with a greater sense of trust and reduced perceptions of threat, in addition to lower levels of cortisol, a stress hormone. This combination may create an environment in which people feel safe disclosing information to their partner.

Conversely, and contrary to popular belief, mixing alcohol with sex is unlikely to lead individuals to divulge more of their important secrets. Immediately following sex, people who have been drinking are likely to say things to their partner that they hadn't intended to disclose, but their pillow talk consists of less important information and is less positive than that of people who drink less on average.

"Oxytocin is an 'upper' and alcohol is a 'downer,' so it's not surprising that they have opposite effects on behavior," said Tamara Afifi, Professor at the University of Iowa, and co-author of the study. "People who drink more alcohol on average perceive fewer benefits to disclosing information to their partners."

Alcohol combined with failing to have an orgasm results in even more negativity. The study suggests both that orgasm may counteract the negative effects of alcohol consumption on communication after sexual activity and that people who regularly drink greater amounts of alcohol before having sex may have developed communication patterns that interfere with positive post-sex communication.

*  *  *  *  *

Story Source: Materials provided by National Communication Association.  Amanda Denes, Tamara D. Afifi. Pillow Talk and Cognitive Decision-making Processes: Exploring the Influence of Orgasm and Alcohol on Communication after Sexual Activity. Communication Monographs, 2014

Is it talent? Or hard work? Science has an answer.

freelance-writing.lovetoknow.com

 The conclusion of the researchers is this: 

Becoming an expert takes more than practice. 

We all know people, writers in this case, who work very hard at their craft yet never quite achieve success.  Our egalitarian hard work mantra states that if you put in at least 10,000 hours of practice, you'll become good.  An expert perhaps.

Take professional baseball players.  It takes incredibly hard work to make it to the major leagues.  Dedication and perspiration is the least it takes.

Yet, most players hit somewhere around .230 or .250.  Why?  The obvious answer is innate ability.  As coaches will tell you, "you can't teach speed." Apparently you can't teach a .300 batting average or hitting 25+ homeruns either.

I once was part of a critique group with a woman who worked harder than any of the rest of us, and had worked very hard for years.  I don't know how many hours she had put in, but it's a good guess that she had passed the 10,000 hour threshold. Her story lines were well thought out, often intriguing.  Yet her prose was wooden.  Her dialogue was stiff and artificial. Her ideas were great, but she just couldn't deliver them on paper.*

Here's the story:

Practice over time does not seem to play a huge role in performance
Deliberate practice may not have nearly as much influence in building expertise as we thought, according to research. The new study indicates that the amount of practice accumulated over time does not seem to play a huge role in accounting for individual differences in skill or performance.

Scientists have been studying and debating whether experts are "born" or "made" since the mid-1800s. In recent years, deliberate practice has received considerable attention in these debates, while innate ability has been pushed to the side, due in part to the famous "10,000-hour rule" coined by Malcolm Gladwell in his 2008 book Outliers.

The new study, from psychological scientist Brooke Macnamara of Princeton University and colleagues, offers a counterpoint to this recent trend, suggesting that the amount of practice accumulated over time does not seem to play a huge role in accounting for individual differences in skill or performance.

"Deliberate practice is unquestionably important, but not nearly as important as proponents of the view have claimed," says Macnamara.

Macnamara, with colleagues David Z. Hambrick of Michigan State University and Frederick Oswald of Rice University, scoured the scientific literature for studies examining practice and performance in domains as diverse as music, games, sports, professions, and education.

Of the many studies they found, 88 met specific criteria, including a measure of accumulated practice and a measure of performance, and an estimate of the magnitude of the observed effect.  The researchers took the 88 studies and performed a "meta-analysis," pooling all of the data from the studies to examine whether specific patterns emerged.

Nearly all of the studies showed a positive relationship between practice and performance: The more people reported having practice, the higher their level of performance in their specific domain.
Overall, practice accounted for only about 12% of individual differences observed in performance across the various domains.

However, the domain itself seemed to make a difference. Practice accounted for

• about 26% of individual differences in performance for games,
• about 21% of individual differences in music, and
• about 18% of individual differences in sports.

But it only accounted for

• about 4% of individual differences in education and
• less than 1% of individual differences in performance in professions.

Furthermore, the findings showed that the effect of practice on performance was weaker when practice and performance were measured in more precise ways, such as using practice time logs and standardized measures of performance.

Deliberate practice is important

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"There is no doubt that deliberate practice is important, from both a statistical and a theoretical perspective. It is just less important than has been argued," says Macnamara. "For scientists, the important question now is, what else matters?"

Macnamara and colleagues speculate that the age at which a person becomes involved in an activity may matter, and that certain cognitive abilities such as working memory may also play an influential role. The researchers are planning another meta-analysis focused specifically on practice and sports in order to better understand the role of these and other factors.

 

* Interestingly, the woman in question did achieve success.  She knew someone who knew someone who knew an established television producer.  Through this pipeline the producer received some of her story synopses, which he purchased and had developed by the writers on his shows.  She made good money, which offers another insight into success.  It's who you know that at least opens the door to achievement.

 *  *  *  *  *

Story Source: Materials provided by Association for Psychological Science. 1.B. N. Macnamara, D. Z. Hambrick, F. L. Oswald. Deliberate Practice and Performance in Music, Games, Sports, Education, and Professions: A Meta-Analysis. Psychological Science, 2014

Men with negative, sexist attitudes towards women use assertive courtship strategies

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This research, while obvious in its conclusions, offers an interesting insight into the dynamics of relationships between men and women.  For Romance authors, especially, this explains why so many women find it so difficult to find a "nice" guy.  Well, nice guys get screened out by the misogynists of society, even though their primary target are women who could be classified misogynists as well.

Guys, if you're wondering why women tend to gravitate toward jerks?  It's because the jerks are so much more aggressive in their courtship, working to screen you out of developing any sort of a relationship with a woman.

Make sense?  Here's the story:

Men with a preference for 'one-night stands' and negative sexist attitudes towards women are more likely to use aggressive courtship strategies. They compete with other men who are also interested in the woman, tease the woman, and isolate her away from her friends. In response, women with a preference for 'no strings attached' sex and negative attitudes towards other women are more likely to respond to men's aggressive strategies.
 
Researchers set out to understand the characteristics of men who use aggressive courtship strategies, based on speed seduction techniques described in the US bestseller "The Game" by Neil Strauss and the popular cable TV program "The Pickup Artist." They also studied the characteristics of women who find such strategies appealing.

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The researchers conducted two surveys. The first pilot study surveyed a sample of 363 college students from a large Midwestern university in the US. The second, larger national study recruited 850 adult volunteers via the Internet. The authors asked both male and female participants about their sexist attitudes toward women and whether they were willing to take part in uncommitted or short-term sex. They also asked about the extent to which men used assertive strategies to initiate relationships and the extent to which women found these approaches desirable.

The results showed that men who were keen on 'one-night stands' were more likely to use aggressive strategies when flirting with women, and women who were also open to casual sex were more likely to respond to this type of aggressive courtship. In addition, men with negative, sexist attitudes towards women, justifying male privilege, were more likely to use assertive strategies, which may serve to 'put women in their place' in a submissive or yielding role during courtship. Women with sexist attitudes towards members of their own gender were more likely to be responsive to men's assertive strategies. This suggests that they find men who treat them in a dominant way during courtship more desirable, because it is consistent with their sexist ideology.

They conclude: "Our results suggest that assertive courtship strategies are a form of mutual identification of similarly sexist attitudes shared between courtship partners. Women who adopt sexist attitudes are more likely to prefer men who adopt similar attitudes. Not only do sexist men and women prefer partners who are like them, they prefer courtship strategies where men are the aggressors and women are the gatekeepers."

*  *  *  *  * 

Story Source:  Materials provided by Springer.  Hall JA & Canterberry M. Sexism and assertive courtship strategies. Sex Roles, 2011

The Story of Us: White skin is not about making vitamin D. It's about preventing dehydration.

Credit: © cristovao31 / Fotolia

The Elias lab has shown that pigmented skin provides a better skin barrier,

which was critically important for protection against dehydration.

You're writing a story about the migration of ancient humans into Europe.  As always, you need crisis as a way of furthering the story.  Here's one, minor though it may seem:  On the trip, members of your band with dark skin are much more likely to die of dehydration than members with a lighter skin tone.

Really?  Sure.  Read the following which debunks the Vitamin D theory of why people with lighter colored skin survived as they followed the glaciers north after the last Ice Age. 

The popular idea that Northern Europeans developed light skin to absorb more UV light so they could make more vitamin D – vital for healthy bones and immune function – is questioned by UC San Francisco researchers in a new study published online in the journal Evolutionary Biology.
 

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Ramping up the skin’s capacity to capture UV light to make vitamin D is indeed important, according to a team led by Peter Elias, MD, a UCSF professor of dermatology. However, Elias and colleagues concluded in their study that changes in the skin’s function as a barrier to the elements made a greater contribution than alterations in skin pigment in the ability of Northern Europeans to make vitamin D.

Elias’ team concluded that genetic mutations compromising the skin’s ability to serve as a barrier allowed fair-skinned Northern Europeans to populate latitudes where too little ultraviolet B (UVB) light for vitamin D production penetrates the atmosphere.

Among scientists studying human evolution, it has been almost universally assumed that the need to make more vitamin D at Northern latitudes drove genetic mutations that reduce production of the pigment melanin, the main determinant of skin tone, according to Elias.

“At the higher latitudes of Great Britain, Scandinavia and the Baltic States, as well as Northern Germany and France, very little UVB light reaches the Earth, and it’s the key wavelength required by the skin for vitamin D generation,” Elias said.

Skin color has nothing to do with production of Vitamin D
“While is seems logical that the loss of the pigment melanin would serve as a compensatory mechanism, allowing for more irradiation of the skin surface and therefore more vitamin D production, this hypothesis is flawed for many reasons,” he continued. “For example, recent studies show that dark-skinned humans make vitamin D after sun exposure as efficiently as lightly-pigmented humans, and osteoporosis – which can be a sign of vitamin D deficiency – is less common, rather than more common, in darkly-pigmented humans.”

"Dark-skinned humans make vitamin D after sun

exposure as efficiently as lightly-pigmented humans."

Furthermore, evidence for a south to north gradient in the prevalence of melanin mutations is weaker than for this alternative explanation explored by Elias and colleagues.

Skin as a barrier to water loss
In earlier research, Elias began studying the role of skin as a barrier to water loss. He recently has focused on a specific skin-barrier protein called filaggrin, which is broken down into a molecule called urocanic acid – the most potent absorber of UVB light in the skin, according to Elias. “It’s certainly more important than melanin in lightly-pigmented skin,” he said.

In their new study, the researchers identified a strikingly higher prevalence of inborn mutations in the filaggrin gene among Northern European populations. Up to 10 percent of normal individuals carried mutations in the filaggrin gene in these northern nations, in contrast to much lower mutation rates in southern European, Asian and African populations.

Moreover, higher filaggrin mutation rates, which result in a loss of urocanic acid, correlated with higher vitamin D levels in the blood. Latitude-dependent variations in melanin genes are not similarly associated with vitamin D levels, according to Elias. This evidence suggests that changes in the skin barrier played a role in Northern European’s evolutionary adaptation to Northern latitudes, the study concluded.

Yet, there was an evolutionary tradeoff for these barrier-weakening filaggrin mutations, Elias said. Mutation bearers have a tendency for very dry skin, and are vulnerable to atopic dermatitis, asthma and food allergies. But these diseases have appeared only recently, and did not become a problem until humans began to live in densely populated urban environments, Elias said.

The Elias lab has shown that pigmented skin provides a better skin barrier, which he says was critically important for protection against dehydration and infections among ancestral humans living in sub-Saharan Africa. But the need for pigment to provide this extra protection waned as modern human populations migrated northward over the past 60,000 years or so, Elias said, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago.

The data from the new study do not explain why Northern Europeans lost melanin. If the need to make more vitamin D did not drive pigment loss, what did? Elias speculates that, “Once human populations migrated northward, away from the tropical onslaught of UVB, pigment was gradually lost in service of metabolic conservation. The body will not waste precious energy and proteins to make proteins that it no longer needs.”

*  *  *  *  *

Story Source:  The above story is based on materials provided by University of California, San Francisco (UCSF), written by Jeffrey Norris.  1.Jacob P. Thyssen, Daniel D. Bikle, Peter M. Elias. Evidence That Loss-of-Function Filaggrin Gene Mutations Evolved in Northern Europeans to Favor Intracutaneous Vitamin D3 Production. Evolutionary Biology, 2014