In The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, Gregory Cochran and Henry Harpending estimate that by the end of the last Ice Age there may have been 6 million hunter-gatherers world wide. The subsequent advent of agriculture vastly increased the amount of food available, as humans didn’t merely have to rely on what was readily available in nature but could grow their own food. This allowed those who practiced it to greatly expand their numbers, but the nutritional quality may well have been poor at first.
As Cochran and Harpending point out, the genetic changes underlying light skin in Europe and East Asia are not identical, although both of these groups faced similar evolutionary pressures. In most parts of the world, even in temperate regions, everyone has dark eyes and dark hair. To us these facts suggest that there was something fundamentally different in the selective forces affecting skin color in Europe and East Asia. If those forces were different, at least one of them was probably selecting for something other than vitamin D.
We don’t have access to all the genetic data just yet, but blond hair appears to be caused by a younger mutation than red hair. Most likely, when the Lascaux cave paintings were created by the end of the Upper Paleolithic (ca. 15,000 BC) not a single human being in the world had either blond hair or blue eyes. It is interesting to speculate why some Europeans developed blue eyes whereas people in northeast Asia, who experienced comparable evolutionary pressures for light skin (and quite probably high IQ as well), didnt’tevolve the same wide range of eye colors as Europeans did, from brown to blue, green, gray or hazel eyes.
Blue eyes are common in many European populations but are nearly nonexistent in the rest of the world. They can occasionally be found in nearby areas such as northern Syria, among the Berbers of northwestern Africa or in regions which have been exposed to European genetic influences in the past, for example Afghanistan or parts of Central Asia since the Indo-European expansion, Alexander the Great and his men or certain traders and adventurers.
Read the rest at Tundra Tabloids.
1 comments:
Here are maps of predominant skin colour, eye colour and hair colour in Europe and beyond.
They don't exactly overlap with each other, but they're pretty close. And they don't follow a strict north-south pattern either. Instead, light-coloured skin, eyes and hair are all centered on the Baltic Sea and spread out from there.
I've heard that the Baltic is the world's northernmost area where grain can be grown, so maybe that's why the mutations started there and only there. Light-coloured skin, eyes and hair were all needed to obtain enough vitamin D to survive at that latitude after neolithic man's diet switched from meat to grain.
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