On skin colour

The recent discovery of the evidence of tuberculosis striking ancient humans illustrated by telltale signs in the skull of a homo erectus discovered in Turkey further lends credence to a plausible theory of race and skin colour.

The theory goes something like this. The original human beings evolved around the regions below the Horn of Africa. It is now believed that most of the original humans were very dark skinned. The dark skin gave them protection against the intense ultraviolet radiation from the African sun. (Light is absorbed lesser by dark colours than lighter colours and hence blocked the harmful UV better...) Again the dark skin was purely an artifact of evolution rather than a random colour assigned by forces beyond comprehension. By and by, the proto humans migrated out of the horn of Africa, following the Red Sea all the way taking a route along modern day Palestine, onto Syria, then Turkey and the vast beyonds... As they moved north, the sun became less bright, the climes colder and the vegetation less tropical. As it turns out, the explorers found that their dark skins were now an impediment rather than a blessing. The cause lay with the synthesis of vitamin D (Vitamin D is produced photochemically in the epidermal layer of skin and is not available freely in nature)... The less intense sun could not penetrate the darker skinned migrants and a lot of them found themselves depleted of vitamin D. Reduction in vitamin D leads to a weakened immune response to bacteria’s and for the Leptomeningitis tuberculosa bacterium (the one that causes a special form of tuberculosis), the migrants were a choice prospect to infect. Many migrant ran afoul of the bacterium and a chance few who had the odd mutation that resulted in lighter skin colour escaped (the lighter skin colour meant more vitamin D synthesis that resulted in a stronger immune response and a proportionately higher resistance to diseases like tuberculosis and the like). The random genetic mutations that resulted in the now favorable light skin started to build up as the migrants and their generations started settling in lands farther north. Of course, many, many more mutations will pass before we get to the cornucopia of human skin colours today, but in a nutshell, this is a leading theory that is gaining grounds in an attempt to explain the diversity of skin colours that we see around us…

The findings are reported in the current issue of The American Journal of Physical Anthropology (abstract here) by a team of American, Turkish and German researchers. The researchers have maintained that the new evidence “permits us to speculate that a case of TB was exacerbated by the reduced level of ultraviolet radiation encountered during the expansion of a low-latitude population of dark-skinned Homo into temperate Turkey.”

Again, all this is speculation, but the case is gaining ground and becoming stronger… Further research into the scattered bones of our ancestors along the ancient migration routes will surely settle this argument. I wonder what Dr. Watson, who is now famous for his macaca type slurs would have to say…

Pierre Mathurin Petraud, ‘On the Nile’, Oil on canvas, 22” X 18”