One of the great mysteries in recent human evolution is why did skin colour become lighter as humans migrated North.  While it’s obvious why people in warmer climates need dark skin (protects them from the sun), scientists have long been puzzled by why light skin was selected for in cold climates.  The tentative hypothesis (that light skin is better at generating vitamin D) has never seemed entirely satisfying, but scientists have gone with it because it was the best hypothesis they had.

HBDers have long believed that light skinned people are more intelligent, but less aggressive and sexually active than dark skinned people.  This has long been assumed to be the case because cold climates independently select for both light skin (vitamin D production) and intelligence (survival skills).  But what if there were a direct link between intelligence and skin colour itself?

Commenter “Lion of the Judah-sphere” has pointed me to a heated debate between science expert Razib and other HBDers about whether skin colour might be intrinsically related to intelligence, sexuality and aggression.  If so, it might suggest that the real reason humans evolved lighter skin as they moved North, was not just because they needed more vitamin D, but because they needed more intelligence, less aggression, and more sexual restraint, and these traits are controlled by the some of the same genetic variants that affect skin colour.

Reviewing the animal literature, scholar J.P. Rushton found that dark skinned lions are  more aggressive and sexually active than light skinned lions.  Replicating such findings in over 40 species of wild vertebrates, Rushton reported that darker pigmented individuals were not only more aggressive and sexually active, but had larger body mass, greater stress resistance, and more physical activity.  So robust is the relationship between colouring and behavioral dominance that it’s even been found in four species of fish, four species of reptiles, one amphibian, and 36 species of birds.

Studies of albinos find that they don’t do any better than normal people on official IQ tests, but they do perform better on tests of reading, spelling, and arithmetic skills, which are correlated with general intelligence (especially reading and arithmetic which are among the most g loaded skills ever studied).  One possibility is that albinos are indeed more intelligent, but official IQ tests, with their emphasis on visual-spatial motor abilities, are biased against albinos who typically suffer from very bad vision.  The bad vision itself may be additional evidence of the high genetic intelligence of albinos, since myopia is widely believed to be caused by the same genetic variants that cause high IQ, and the popular stereotype of the high IQ nerd who wears glasses appears to be based on genetic reality.