I remember an old vitamin D book – I believe it was Feldman’s Vitamin D – that argues that if we are going down the Transsahara Route (Algier-Lagos) human skin color gets always darker towards Tamanrasset due to increased solar power- also known known as the Loomis hypothesis (Science 1967).
So , let’s have a look at three maps. Solar power first.
Second, skin tones – the Tamanrasset observation is correct but the overall picture does not match the Loomis hypothesis.
Neither does the new vitamin D map published last week in the Lancet.
Maps are still patchy but let me already believe that the Loomis hypothesis is wrong.