The glacier mummy "Ötzi" is probably the most famous prehistoric European. However, its remains still hold surprises. A new, more precise genome analysis of the Copper Age man, who died around 5,300 years ago, reveals that our assumptions about his appearance were apparently wrong. Because according to his genes, Ötzi was almost as dark-skinned as his mummy is today and was bald. More than 90 percent of his genome corresponds to that of Neolithic Anatolian farmers. Ötzi thus has significantly fewer genetic elements of Stone Age hunter-gatherers than most other Europeans of his time. The new genome analyzes of the glacier mummy also shed new light on the population in the Alpine region of the Copper Age.
There is probably no other person from the early European past who has been studied as well as "Ötzi", the glacier mummy from the Copper Age preserved in the ice of the Ötztal Alps. Ever since hikers discovered the well-preserved remains of this man in 1991, they have provided unique information about his origins, life and health. Material analyzes revealed where the Copper Age man's clothing and weapons came from and what they were made of. Analyzes of his provisions and stomach contents also revealed what Ötzi had eaten before his death. Studies of his injuries even provided the first clues as to how the man was killed around 5,300 years ago - even if all the circumstances of his death are not yet clear. In 2012, a research team also managed to extract and analyze DNA from a bone sample of the glacier mummy. The results suggested, among other things, that Ötzi had brown hair and eyes and was more of a moderate Mediterranean type.
Surprisingly high proportion of Anatolian ancestors
However, the genome data obtained in 2012 was still relatively rough and incomplete because DNA sequencing methods were not that advanced. That's why a research team led by Ke Wang from the Max Planck Institute for Evolutionary Anthropology in Leipzig has now taken another look at the genome of the famous glacier mummy. To do this, the scientists again took a small bone sample from Ötzi's hip bone and analyzed the DNA using modern high-throughput sequencing. The result is a much better covered and more precise reconstruction of Ötzi's genome, which also shows fewer modern contaminations due to new filter methods, as the researchers explain. Based on this new genome, they first used DNA comparisons with modern and contemporary European populations to investigate the origin of the glacier man.
The analyzes revealed something surprising: "The glacier man had more Neolithic farmers among his ancestors than any other European of the fourth millennium BC we studied," report Wang and his colleagues. According to their results, more than 90 percent of Ötzi's genome matched that of the first farmers who immigrated to Europe from Anatolia in the Neolithic Age. "Genetically, it looks as if its ancestors came directly from Anatolia," explains senior author Johannes Krause from the Max Planck Institute for Evolutionary Anthropology. This suggested that Ötzi came from a relatively isolated Alpine population with little contact with other European groups. The rest of Ötzi's genome goes back to the hunter-gatherers who lived in Europe before Neolithic evolution and the immigration of early farmers. In contrast to the analysis from 2012, Krause and his team could not detect any DNA from the Bronze Age steppe nomads in Ötzi's genome, who migrated to Europe from the Eurasian steppe around 4,900 years ago. "From this we conclude that the previously determined 7.5 percent fraction of this steppe DNA is most likely due to modern contamination," explains the team.
Dark skin and bald head
The new genome analysis also provides new insights into the appearance of the glacier man. Krause's team compared Ötzi's DNA with around 170 gene variants in the human genome that influence skin pigmentation. It turned out that Ötzi had even darker skin than previously thought. "It is the darkest skin tone that has been detected in European finds from the same period," explains co-author Albert Zink from the Institute for Mummy Research at Eurac Research in Bolzano. Ötzi's skin was therefore more pigmented than that of today's inhabitants of Sardinia or other Mediterranean populations. This also sheds new light on the mummy of the glacier man: "Previously, it was thought that the mummy's skin had darkened during storage in the ice, but what we are seeing now is probably Ötzi's original skin color," says Zink. “Of course, knowing this is also important for conservation.”
Apparently, the previous ideas about Ötzi's appearance are also wrong with regard to his hair: Previous reconstructions always showed the glacier man with long, slightly wavy brown hair and a thick beard. However, a gene variant in his genome linked to early hair loss now suggests that Ötzi was probably bald at the time of his death, or at most had a sparse fringe of hair. "This is a relatively clear result and could also explain why almost no hair was found on the mummy," says Zink. An increased risk of obesity and type 2 diabetes was also part of Ötzi's genes, but thanks to his healthy lifestyle it probably didn't come into play.
Overall, the new genetic reconstruction provides several new insights into the origin, health and appearance of the famous glacier man - and corrects some misconceptions.
"The genome analyzes revealed phenotypic features such as strong skin pigmentation, dark eye color and male pattern baldness, which are in stark contrast to previous reconstructions," says Krause. "It is remarkable how strongly the reconstruction is distorted by our own ideas of a European Stone Age man." Elisabeth Vallazza, director of the South Tyrol Museum of Archaeology, which houses a reconstruction based on earlier findings, comments: With the Ötzi figure exhibited in the museum Another aspect is in the foreground: "The main thing was to show that Ötzi was a modern person: middle-aged, tattooed, wiry, weather-beaten, a person like you and me," says Vallaza. A revision of the reconstruction is currently not planned.
Source: Ke Wang (Max Planck Institute for Evolutionary Anthropology, Leipzig) et al., Cell Genomics, doi: 10.1016/j.xgen.2023.100377