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## What the Finding Changed About Understanding Early European Skin Color
The 2018 Cheddar Man results were striking in the popular press, but they were not, as Mark Thomas noted, surprising to ancient DNA researchers. The reason they weren’t surprising is that the finding was consistent with a picture that had been building from multiple ancient DNA studies over the preceding decade.
The earliest comprehensive ancient DNA studies of Mesolithic European hunter-gatherers, published in the early 2010s, found that Mesolithic individuals from Spain and other parts of western and central Europe carried genetic variants associated with darker skin pigmentation — the same variants that are largely absent from modern European populations but common in people of African, South Asian, and Southeast Asian ancestry. This was unexpected when the first results came in, but the pattern replicated across multiple specimens from multiple sites.
The implication was clear, if initially difficult to communicate to a general audience accustomed to thinking of “ancient Europeans” as a relatively homogeneous group: the people who lived in Europe during the Mesolithic did not have the same pigmentation profile as the people who live in Europe today. The lighter skin tones characteristic of modern northwestern European populations are a later development, associated with genetic changes that spread through European populations after the Neolithic revolution — after farming arrived, after new migration waves brought new genetic material, and after millennia of ongoing natural selection continued to shape the pigmentation profile of European populations.
The prevailing scientific understanding of why lighter skin evolved in European populations involves vitamin D synthesis. Human skin produces vitamin D when exposed to ultraviolet radiation from sunlight. At the relatively low-latitude environments where modern humans evolved in Africa, exposure to ultraviolet radiation is sufficient for vitamin D production even with highly melanized skin. At the higher latitudes of Europe, where sunlight is weaker and more oblique for much of the year, darker skin may impair vitamin D synthesis enough to cause deficiency. Lighter skin admits more ultraviolet radiation and thus maintains vitamin D synthesis in lower-sunlight environments.