In Human Evolution, Changes in Skin’s Barrier Set Northern Europeans Apart

Jeffrey Norris, UCSF, June 30, 2014

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.

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.

“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.”

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.

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.”

For the Evolutionary Biology study, labeled a “synthesis paper” by the journal, Elias and co-author Jacob P. Thyssen, MD, a professor at the University of Copenhagen, mapped the mutation data and measured the correlations with blood levels of vitamin D. Labs throughout the world identified the mutations. Daniel Bikle, MD, PhD, a UCSF professor of medicine, provided expertise on vitamin D metabolism.

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  • David Ashton

    Was there a coincidental correlation with skull formation, brain size and delicacy of features?

    • journey

      In accordance with PC, all determined by evolutionary factors, nothing to do with inherent racial genetic differences.

      • Were not these inherent differences also formed by the environment?

        • journey

          Inherent means the genes were already there but can be or
          not influenced by the environment. For example, the gene(s) for intelligence, we know there is/are one(s) because of the vast differences between say blacks and whites. The racial makers (like hair/skin texture and color or eye color) cannot be changed by the environment or by evolution except through inter-racial breeding. Academia has tried to explain away inherent racial differences by those two factors due to the current egalitarian propaganda. In other words, the characteristics of the different races appeared suddenly as is and cannot be changed by external factors.

          The environment can enhance superior genes but cannot
          turn inferior genes into superior ones otherwise the blacks would have eventually evolved closer to the means of the whites or even the Asians. This country has spent trillions in trying to prove or disprove the theory of nature vs nurture. It has not moved the needle one bit in improving black intelligence. Another example is the American Indians. In reality,
          their inherent genes were superior to the blacks but they did not receive an injection of the genome that the ancient Greeks carried. This is the primarily reason for them still being in the Stone Age when the white man appeared. The ancient Greeks, Egyptians, and Aryans were carriers of the superior genes that accelerated innovation and inventions both technologically and socially. Currently, the white race is the carriers of these superior genes. It is very worrisome that whites are currently being portrayed as demons when they are the ones that will greatly advance the whole of humanity. The full potential of the superior genes are still evolving (being expressed) as shown by the continuous advances in technology, arts, social structures, etc.

          Just for historical interest, you might be interested in reading about this – Ancient Computer Baffles Scientists: Antikythera Mechanism …www.theepochtimes.com/…/773279-ancient-computer-baffles-scientists-… if you did not know about it already. But we currently are making the similar mistakes as the ancient Greeks, the constant importation of inferior genes for manual labor. Eventually, they became the minority in addition they were also breeding with them. Eventually the superior genes became submerged (no longer could be expressed). The Aryans also tried to save themselves by installing the caste system but it failed.

          This is just a very brief synopsis of the evolution of man on this planet.

    • me

      Evolutionary, ‘out of Africa’ theory is sooooo full of holes that it gives Swiss cheese a run for the money. The Adamites are a mystery, for now.

      • journey

        You are correct! The human race did not evolve from blacks. And the blacks migrated into Africa from India. There is only one source on this planet that you could have gotten the word, ” Adamites” from.

        Richard Leakey’s theories became dominant in academia. He won the power struggle.

  • MekongDelta69

    A ‘study’ by UC San Francisco…

    Skip article.

    Next

    • APaige

      Sometimes they let the truth out: “evidence suggests that changes in the skin barrier played a role in Northern European’s evolutionary adaptation to Northern latitudes.” Well that is unless ‘evolutionary adaptation’ is considered a social construct.

  • Look_A_Squirrel

    “The body will not waste precious energy and proteins to make proteins that it no longer needs.” That explains why each generation of welfare recipients is dumber than the one before.

    • Rhialto

      To enhance your nightmares, wikipedia “.Spiegelman Monster”

  • haroldcrews

    The observation that osteoporosis ought to be higher in those with higher levels of melanin does not take into account the fact that sub-Saharan Africans typically have denser bones than Europeans.

  • journey

    “The data from the new study do not explain why Northern Europeans lost melanin.”

    How about skin color is just part of the package that identifies the different races from day one? In other words, skin color is determined by the inherent racial genes.

  • Luca

    In my humble opinion, melanin appears to have been sacrificed for a greater brain capacity.

    • journey

      What if the differences in racial intelligence were already coded into the genetic base from day one? That is some of the races are inherently higher in intelligence than others. For the last 60+ years, this country has wasted trillions to disprove this.

      The whites have the highest capabilities to think abstractly which is one of the main reasons for them being the main innovators and inventors on this planet.

    • Einsatzgrenadier

      This has already been demonstrated empirically. National IQ and average melanin concentration are highly correlated. The darker the skin color, the dumber the population.

      • Bossman

        When white men are injected with melanin they begin to feel sexier so there may be more to the phenomenon of skin pigmentation.

        • Luca

          And they lose 30 IQ points. Señor Troll.

        • me

          Sure. Why not? Of course. Genius. Now why don’t you go peddle your papers over to Huffy Post, where they appreciate this kind of fairy tale…..

        • ElComadreja

          Do they also develop a taste for Colt 45, crack, murder, rape and a decreased desire to work for a living?

          • Bossman

            I don’t know but you can use Google to find out more about this phenomenon.

          • From another crackhead?

  • dd121

    Like so much science over they past 30 years, they’re just guessing. Anyway, so what?

  • William Allingham

    i think it could be explained the same way as blue eyes, by sexual selection everybody agrees that fair skin is more valuable in potential partners and looks good, just like blond hair and light eyes, this reminds me of many species of birds and plants who use beautiful shapes and colors to attract mates or “clients”.

    • I was most attracted to my wife by her ivory-colored skin. Sakaya’s black hair sets that off rather nicely.

      • William Allingham

        well, not everybody, but I could say a majority. John V Day makes the argument that in Indo-European Art and languages fair skin is often praised not to mention the obsession today in Central America with European traits.

        in any case in reality women tend to have fairer skin than men.

  • Carlos Geary

    People of Northern Italy, Northern Greece, Northern Spain, look like Scandinavians.

  • Tim_in_Indiana

    I don’t really care why Europeans evolved light skin. It still doesn’t negate the fact that there are differences between the races.

    • LHathaway

      Yes, the races are different. I suspect whites are less intelligent.