Ötzi’s genome carried the genetic markers associated with dark skin pigmentation.

He did not carry the genetic variants that produce the light skin tones characteristic of most modern European populations.

In the language of population genetics, the genes for light skin tones had not yet become prevalent in European populations during Ötzi’s lifetime — that transition occurred later, estimated at roughly 4,000 to 3,000 years ago, and was associated with the spread of agricultural populations whose diet was lower in vitamin D than that of the hunter-gatherers who preceded them.

The explanation for the light-skin evolution is biological: darker skin produces more melanin, which provides protection against ultraviolet radiation but also reduces the skin’s ability to synthesize vitamin D from sunlight.