By roughly five thousand years ago — the period in which Ötzi was alive — this mixing had been going on for three thousand years. Most Neolithic European individuals from the fourth millennium BCE carried a mixture of Anatolian farmer and Western Hunter-Gatherer ancestry, with the proportions varying by region and individual history. Finding someone with as little hunter-gatherer admixture as Ötzi showed — roughly ten percent — suggested that his particular community had been unusually isolated from the ongoing admixture process.
The steppe herders, whose expansion came later — roughly 4,900 years ago, associated with the Yamnaya and related cultures — are a third layer in this story. Their expansion brought Indo-European languages, the pastoralist lifestyles of the Pontic-Caspian steppe, and new technology. Most modern Europeans carry ancestry from all three sources: ancient hunter-gatherers, Neolithic Anatolian farmers, and Bronze Age steppe herders. Ötzi, who died before the steppe expansion reached Central Europe, should not have had steppe ancestry; confirming that he did not — after the apparent contamination-driven artifact of the 2012 finding — was a key piece of the 2023 reanalysis.
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## The Skin Color Question: What the DNA Can and Cannot Say
Among the phenotypic findings from the 2023 study, the prediction of dark skin drew the most attention and provoked the most significant reassessment of how Ötzi had been depicted.
Genomic prediction of skin color is a probabilistic tool, not a determination. The method used by the Wang et al. team employed 170 single-nucleotide polymorphisms (SNPs) identified by a genome-wide association study of UK Biobank participants as predictors of skin pigmentation variation. Of those 170 markers, 154 were genotyped successfully in Ötzi’s high-coverage genome. The weighted sum of dark-pigmentation alleles at those sites produced a score of 0.591.