View Single Post
Old December 20th, 2009 #1
Zenos
Senior Member
 
Join Date: Sep 2005
Posts: 3,514
Default Why are Europeans White?

A theory as to why Europeans are White. Naturally, the article says that skin color is merely superficial.

http://knol.google.com/k/frank-w-swe...eans-white-e1#


Why Are Europeans White? (E1)
--
Tells why northern Europeans are so oddly de-pigmented compared to everyone else on the globe. Session E1 of a series of topics discussed by the Second Life "The Study of Racialism" group. It is part of our molecular anthropology series. The prior session, E5 discussed the migrations that carried our species around the globe in prehistoric times. This topic looks at later regional adaptations.

The Puzzle: Northern Europeans are Uniquely Depigmented

"White," of course, is a a social designation. The question really is, "Why are northern Europeans depigmented?" Here is a map of human skin tone. The natives of northern Europe are oddly light-skinned. They are paler than anyone else on earth.

Most people know that it has something to do with sunlight, UV, latitude, and vitamin D. Here is a map of solar UV at the surface taken from satellite. It matches the skin-tone map everywhere but Europe.

The closer you are to the equator, the darker your skin. This is because humans are extraordinarily sensitive to sunlight on the skin. Humans lack fur.
It Has Something to do With Solar UV and Oceans

UV rays produce vitamin D and reduce folate when they hit naked skin. And embryos are terribly vulnerable to both substances in the mother. When it comes to sunlight and skin tone, furless humans are balanced on a knife-blade.

Too much UV penetrating the skin (too pale-skinned under intense sunlight) increases Vitamin D but reduces folate. Lack of folate causes neural tube defects in the fetus, causing such congenital abnormalities as craniorachischisis, anencephalus, and spina bifida, leading to many miscarriages.

On the other hand, too little UV penetrating the skin (too dark-skinned under dim sunlight) increases folate but reduces vitamin D. Lack of vitamin D causes skeletal neonatal abnormalities (skull, chest, and leg malformations), rickets being the best known. Again, this causes miscarriages.

And so, humans adapt very quickly to solar UV. Prehistoric groups that migrated towards the equator got darker. Prehistoric groups that migrated away from the equator got lighter.

But this explanation fails for Europe. Northern Europeans are lighter than everyone to the south (Mediterraneans), to the east (Mongols and east-Asians), to the west (Native Americans across the Atlantic), and to the North (Inuit, Sammi, Chukchi, Aleut).

Clearly, there once was a factor at work in Europe other than dim sunlight.
Here is another map of skin tone. Again, the blob surrounding the Baltic Sea is like nothing else on the planet. That this pale population surrounds the Baltic gives the first hint. It must have something to do with the oceans.

Skin, Hair, and Eyes: Neoteny

Baltic depigmentation is not just in the skin. Here is a map of hair color. The pigment "melanin" colors hair as well as skin. Adult blondes are native only to the same unique region.



Children around the world are often blonde, but their hair darkens at puberty. So it is not just northern European adult skin that lacks pigment. It is also adult European hair.

The Baltic depigmentation is not just in the skin and hair. Here is a map of eye color. Melanin colors eyes, as well as skin and hair. Adults with blue eyes are native only to the same unique region.

(Babies around the world are often born with blue eyes, but their eyes darken within a few months.)

So it is not just northern European skin and hair that lack pigment. It is also northern European eyes. Skin, hair, eyes: adult European pigmentation resembles that of children elsewhere. This gives the second hint--neoteny.
When Did it Happen?

To solve the puzzle, find out when it happened. When did the inabitants of the Baltic region lose their melanin? It must have happened after 16 KYA (16 thousand years ago). The Baltic region was covered by ice before then and nobody lived there.

In fact, it happened after 13 KYA. Cave art from that time always shows normally pigmented people. Notice that in this painting from 13 KYA, the hunters are the same color as the deer.

It must have happened before 4.6 KYA because depigmented people first began to appear in art at that time. These Egyptian statues were painted in 2613 BC. They portray Prince Rahotep and his consort Nefret, of the Old Kingdom, early Fourth Dynasty. Notice that he is brown but she is pink.

And so, the next step in solving the puzzle is to ask, "What happened in Europe between 13 KYA and 4.6 KYA?"

What happened was the invention and spread of agriculture. Before 10 KYA people everywhere lived by hunting and gathering. Then, almost simultaneously, cereal growing was invented in four spots around the globe:

Iraq (wheat, barley, rye), China (rice), Nigeria (sorghum), and Mexico (corn or maize).
It is Connected With Eating Cereal

What does skin tone have to do with eating cereal? Even in darkness, humans get vitamin D from eating meat and fish. Otherwise they could never inhabit the arctic.

This USDA chart shows the vitamin D content of various foods. All meats have some vitamin D. Fish have very high amounts. But grains have no vitamin D at all.

People who eat grains do not get vitamin D from food; they must get it from sunlight.

This usually works out fine because grains grow only where it is warm. And this means only in latitudes with bright sunlight, with one exception.

People who live in low latitudes, where they can live off grains, get plenty of sunlight. People who live in dim sunlight cannot grow grains, and so they get vitamin D from the meat and fish that they eat.
The Gulf Stream is the Cause

The exception? There is only one spot on the planet where grains will grow despite sub-arctic sunlight.

It is where the warm waters of the Gulf Stream wash ashore. The Baltic is the only place on earth where ocean currents keep it warm enough to grow grain despite dim sunlight.

When the inhabitants of this region switched to grain about 6 KYA, they suddenly got insufficient vitamin D to survive. They had stopped eating mostly meat and fish in a place where sunlight was too dim to produce vitamin D in normally pigmented skin.

And so they adapted by retaining into adulthood the infantile trait of extreme paleness. Blonde hair and blue eyes were other infantile traits that were just swept along accidentally.

For the detailed text of this topic, complete with footnoted references, citations, and all the peer-reviewed material, visit The Paleo-Etiology of Human Skin Tone.

To hear the presentation of this topic as an audio file recorded in Second Life, complete with PowerPoint slides, visit Audio Lecture E1.