Dark skin, bald head, Anatolian ancestry: The latest findings from the Iceman’s genome

Ötzi's genome was decoded for the first time more than 10 years ago. It was also the first time that the genome of a mummy had been sequenced. These results provided important insights into the genetic makeup of prehistoric Europeans. Advances in sequencing technology since then have now enabled a research team from the Max Planck Institute for Evolutionary Anthropology and Eurac Research to reconstruct his genome more accurately. The results of this recent analysis complete the Iceman’s genetic picture and cast aside some older theories: no genetic traces of the Steppe Herders from Eastern Europe were found in Ötzi's genome. In contrast, Ötzi’s genome has an unusually high proportion of genes in common with those of early farmers from Anatolia compared to other contemporary Europeans. In addition, the study yielded entirely new findings about the Iceman’s appearance that call into question his iconic portrayal: at the time of his death, Ötzi almost certainly did not have thick long hair, instead he had advanced hair loss and may have even been bald. Furthermore, his skin was darker than previously thought. Ötzi’s genes also show a predisposition to diabetes and obesity. These findings have just been published in Cell Genomics.

Today, the genetic makeup of most Europeans has mainly resulted from the admixture of three ancestral groups: western hunter-gatherers gradually merged with early farmers who migrated from Anatolia about 8,000 years ago and who were later on joined by Steppe Herders from Eastern Europe, approximately 4,900 years ago.
The initial analysis of the Iceman’s genome revealed genetic traces of these Steppe Herders. However, the refined new results no longer support this finding. The reason for the inaccuracy: the original sample had been contaminated with modern DNA. Since that first study, not only have sequencing technologies advanced enormously, but many more genomes of other prehistoric Europeans have been fully decoded, often from skeletal finds. This has made it possible to compare Ötzi’s genetic code with his contemporaries. The result: among the hundreds of early European people who lived at the same time as Ötzi and whose genomes are available, Ötzi’s genome has more ancestry in common with early Anatolian farmers than any of his European counterparts.
The research team concludes that the Iceman came from a relatively isolated population that had very little contact with other European groups. “We were very surprised to find no traces of Eastern European Steppe Herders in the most recent analysis of the Iceman genome; the proportion of hunter-gatherer genes in Ötzi’s genome is also very low. Genetically, his ancestors seem to have arrived directly from Anatolia without mixing with hunter gatherer groups,” explains Johannes Krause, head of the Department of Archaeogenetics at the Max Planck Institute for Evolutionary Anthropology, Leipzig, and co-author of the study.

The study also yielded new results about Ötzi’s appearance. His skin type, already determined in the first genome analysis to be Mediterranean-European, was even darker than previously thought – “It’s the darkest skin tone that has been recorded in contemporary European individuals,” explains Anthropologist Albert Zink, study co-author and head of the Eurac Research Institute for Mummy Studies, Bolzano: “It was previously thought that the mummy’s skin had darkened during its preservation in the ice, but presumably what we see now is actually largely Ötzi’s original skin color. Knowing this, of course, is also important for the proper conservation of the mummy.”
Our previous image of Ötzi is also incorrect regarding his hair: as a mature man, he most likely no longer had long, thick hair on his head, but at most a sparse crown of hair. His genes, in fact, show a predisposition to baldness. “This is a relatively clear result and could also explain why almost no hair was found on the mummy,” says Zink. Genes presenting an increased risk of obesity and type 2 diabetes were also found in Ötzi’s genome, however these factors probably did not come into play thanks to his healthy lifestyle.