It is a transient attribute

An excellent update on the state of our knowledge regarding skin pigmentation.  From Under the skin: The genetics and natural history of human pigmentation by Razib Khan.

Fascinating and an excellent antidote to the race obsession of our Mandarin Class.  Skin color is evolving around the world and many of the changes are comparatively recent.  

Some things I did not know.

• Neanderthals varied in complexion
• There are occasional different race fraternal twins for natural reasons
• The gene responsible for most of the variation in blue eye color across the world, OCA2-HERC2, has now been discovered and extensively studied.
• Early Western European hunter-gatherers, who roamed the continent up until 7,000 years ago, had very dark skin and blue eyes.
• Paleogenetics makes clear that the genetic ingredients for the typical physical appearance of many modern Europeans came together only 5,000 years ago. The precise combination of light hair, blue eyes, and white skin, seen in many Nordic populations was unknown in prehistory. It was only the fusion of steppe agro-pastoralists with Neolithic farmers and Mesolithic foragers that produced a genetic mix that set the stage for the emergence of what we might think of today as a prototypical European look.
• The lighter skin for more vitamin D story is unlikely to be true
• Darker skin is protective against folate destruction, and so necessary in sunny tropical climates to carry pregnancies to term.
• Different human lineages evolved redheads independently

I did like this observation.

You may have heard about the theory of sexual selection, but my personal experience is that often when scientists fall back on this option it’s because they have no other satisfying explanation. 

It matches what I have noticed among archaeologists.  If they encounter a structure or an artifact with unclear purpose, their strong instinct is to ascribe it to religious ritual.  It's not that they are necessarily wrong but it is definitely a tell for not having any other satisfying explanation. 

Overall, this was not only an excellent update on the current state of play in a rapidly developing scientific field but also an excellent reminder of universal humanism.  Europeans being, as recently as 7,000 years ago, dark skinned is an excellent counterpoint to investing too much emotional energy in terms of skin color.  In times and places it serves as a varying signal but fundamentally it is a transient attribute.