A microscopic image of skin cells.
Posted on 07/04/2014 5:37:17 PM PDT by SunkenCiv
It had been thought that Northern Europeans developed light skin in order to absorb more UV light to process more vitamin D, necessary for healthy bones and immune function. But a new study conducted by a team led by professor of dermatology Peter Elias from the University of California, San Francisco, shows that the changes in skin’s function as a barrier to water loss is more likely. The skin-barrier protein filaggrin is broken down into a molecule called urocanic acid, which Elias says is the most potent absorber of UVB light in the skin. “It’s certainly more important than melanin in lightly-pigmented skin,” he explained. Elias and his team found that up to ten percent of normal Northern Europeans carry mutations in the filaggrin gene, compared to much lower mutation rates in southern European, Asian, and African populations. “Higher filaggrin mutation rates 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. This evidence suggests that changes in the skin barrier played a role in Northern Europeans’ evolutionary adaptation to Northern latitudes,” the study concluded. Pigmented skin would have offered ancestral humans living in sub-Saharan Africa protection against dehydration and infections. “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 in no longer needs.”
(Excerpt) Read more at archaeology.org ...
A microscopic image of skin cells.
Better call this study racist, just to be safe.
:’) Looks like I missed some festivities in #4 and #5.
The Neandertal Enigma"Frayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]
by James Shreeve
in local libraries
Interesting. I read that chimpanzees have white skin as do great apes, so I wonder why humans started off the other way
A remarkable study and hypothesis.
But it drives me nuts when a scientist makes a statement related to evolutionary changes that makes it sound as if an individual organism just switches off a particular characteristic:
“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 in no longer needs.”
I wholeheartedly agree.
I also feel left out when I come upon those “comment removed.”
I miss the good old days, when the deleted comments could still be viewed *after* they’d been removed from the thread. That doesn’t work any longer, I was hugely disappointed when it vanished.
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