I keep seeing the SLC24A5 mutation referred to as ‘the mutation that turned Europeans from black to white’ on various sites, which is incorrect. It only accounts for about one third of the difference between European and Africans, in essence changing Europeans from Asian tan to pasty pink. To understand the range of skin colour range you get across the world, I’m digging out the old Von Luschan scale as a visual aid. These were originally made of opaque glass which was held up to the underarm skin to compare the colour. It wasn’t an exact measurement, but it did give a reasonable guide to the skin tone of the population.
Europeans are typically lighter than 15, and lighter than 12 in Northern Europe. Africans, with absolutely no non-African admixture can be as light as 20, or as dark as the scale gets at 36.
The San are about as light as Africans get without some Eurasian ancestry (seen above), and that’s slightly darker than North East Africans, Arabs and Pakistanis (see skin colour map). The ‘pale skin’ mutation only makes a difference of about six on the Von Luschan scale; one third of the difference between African and European, the specific difference between Asians and Europeans.
The mutation has made virtually no difference to the average skin tone of any population except Northern Europe, although it will have increased the range a of skin colours a little in places like North Africa and South West Asia. As you can see from the map, native North Americans who are completely lacking in the SLC24A5 mutation for pale skin had a skin tone in the same latitudes as Europe of 15 to 17, the same as Southern Spain and Turkey.
Just to see what these skin tones look like in real life, a representative of Northern Europe, Southern Europe and lower Egypt. The mutation to the SLC24A5 gene would make roughly the difference in skin tone between the very pale lady and the tanned Spanish lady in the middle, with the lady on the end probably being as dark as Southern Europeans ever got. It’s frequency is effectively zero in East Asia and was zero in native Americans prior any mixing with Europeans. Some examples of definitely non-mutated SLC24A5 carrying people below.
Notably not black skinned, and lacking ‘light’ SLC24A5.
And as was kindly brought to my attention by one blog reader, a painting showing the Guanches – native north Africans who were isolated on the Canary islands from about 3,000 years ago and were probably lacking in the ‘light-skin’ gene. The Guanches are were described as tall, tanned and often blond – quite notably not as black. As you can see from this contemporary painting they are shown exactly the same as the Spaniards in skin tone (the Guanche is the lowest figure.) They show what native north Africans looked like without any admixture from any other source dating back to the BC era. This means minus Roman, European and sub Saharan ancestry