Skin became more lightly pigmented when modern humans migrated northward out of Africa into Europe and Asia. Evolutionary biologists increasingly accept the hypothesis that pigmentation lightened in order to allow more ultraviolet light to enter the skin, where it can then stimulate the formation of additional vitamin D.
In a recent article in the Journal of Human Evolution, we provided many reasons why this hypothesis is flawed and suggested instead that pigment dilution developed as a form of ‘metabolic conservation’. While abundant pigment was needed to protect our skin from the intense ultraviolet light of equatorial Africa, it was no longer needed in the weaker light of the higher latitudes. Hence, mutations arising in the genes for pigment-producing proteins that reduced pigmentation were retained, because they allowed skin to divert energy towards other, more urgent requirements. [Read more…] about Highlights of the 2013 IID. Part 1: Evolution and filaggrin mutations vs. vitamin D production