The question of “race” is a genetic and medical one – not cultural or based on folklore or ideology. Whether there are physiologically/medically significant differences between ethnic groups is still being studied. These are complicated subjects but skin color is a trivial matter when comparing differences in biology. Are the body organs and immune systems of the different “races” that much different? No, duh…

However, I do suspect that the immense power of skin color as a fear-trigger has a biological origin and logic* – but that is another post.

Another TOI blogger’s post about skin color and “race” has been popular.  “Ashkenazi Jews are not white – Response to Haaretz article”

Let’s have some facts, shall we?  Here is a good piece from Science magazine, digested here

How Europeans Evolved White Skin

 


By Ann Gibbons – 2 April 2015 5:00 pm

Most of us think of Europe as the ancestral home of white people. But a new study shows that pale skin, as well as other traits such as tallness and the ability to digest milk as adults, arrived in most of the continent relatively recently. The work, presented here…offers dramatic evidence of recent evolution in Europe and shows that most modern Europeans don’t look much like those of 8000 years ago.

…Europeans today are a mix of the blending of at least three ancient populations of hunter-gatherers and farmers who moved into Europe in separate migrations over the past 8000 years. The study revealed that a massive migration of Yamnaya herders from the steppes north of the Black Sea may have brought Indo-European languages to Europe about 4500 years ago.

Now, a new study from the same team drills down further into that remarkable data to search for genes that were under strong natural selection—including traits so favorable that they spread rapidly throughout Europe in the past 8000 years.

  • First, the scientists confirmed an earlier report that the hunter-gatherers in Europe could not digest the sugars in milk 8000 years ago
  • … It wasn’t until about 4300 years ago that lactose tolerance swept through Europe.

When it comes to skin color, the team found a patchwork of evolution in different places, and three separate genes that produce light skin, telling a complex story for how European’s skin evolved to be much lighter during the past 8000 years.

  • The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes. And the new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes…that lead to depigmentation and, therefore, pale skin in Europeans today.
  • But in the far north—where low light levels would favor pale skin—the team found a different picture in hunter-gatherers…Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.
  • Then, the first farmers from the Near East arrived in Europe; they carried both genes for light skin. As they interbred with the indigenous hunter-gatherers, one of their light-skin genes swept through Europe, so that central and southern Europeans also began to have lighter skin.

The team also tracked complex traits, such as height, which are the result of the interaction of many genes.

The paper doesn’t specify why these genes might have been under such strong selection. But the likely explanation for the pigmentation genes is to maximize vitamin D synthesis…People living in northern latitudes often don’t get enough UV to synthesize vitamin D in their skin so natural selection has favored two genetic solutions to that problem—evolving pale skin that absorbs UV more efficiently or favoring lactose tolerance to be able to digest the sugars and vitamin D naturally found in milk.