At least that's what modern human genetics says, contradicting the physical anthropology from 30 years ago, because this mummy is really well preserved. Moreover, all the conclusions of geneticists - who, at the beginning of the 21st century, analysed fragments of Ötzi's genome using methods available at that time - keep falling apart. The final verdict is that many other genetic analyses from over a decade ago could be subject to profound revision. Only current methods make it possible to truly sift out archaic DNA from later contamination with human DNA, originating from archaeologists and other researchers of the remains and - shockingly - from geneticists themselves. The contamination occurred before and as part of research conducted several years earlier at the University of Tübingen under the supervision of Albert Zink, because there is no other explanation for what was just discovered in Leipzig in the Iceman's genome. A report on this topic was published in the prestigious "Cell Genomics" journal on August 16, 2023 by Johannes Krause from Max Planck Institute for Evolutionary Anthropology, creator of modern methods of recognising which DNA is ancient and which is modern.

However, let's start from the beginning, that is September 19, 1991, when German tourists, the Simon couple, while hiking in the Alps on the Italian-Austrian border in Tyrol, saw a human body emerging from a glacier. The corpse was so well preserved that it looked very modern from a distance. Mr and Mrs Simon simply went to the police station to find out which of the tourists missing in the Alps had just been found, unfortunately dead.

However, it quickly turned out that the remains of the mummy's clothes and equipment did not fit a modern mountaineer. These included bear, chamois and deer skins, shoes and socks woven from soft grass and bast, a birch bark backpack, a quiver with 14 arrows, a copper shepherd`s axe over half a meter long, mounted on tar and attached with straps to a yew stick, a flint knife and a 1,82-meter long unfinished arch. The University of Innsbruck undertook serious anthropological research on the body remains.

Ötzi's genetic analysis has been attempted several times. There was little material for comparison or the possibility of learning about the entire genome. As a result, we have assumed so far that he had blood of the "0" type; probably he had brown eyes and brown hair. He also suffered from lactose intolerance, common among early hunter-gatherers, as the mutations allowed to enjoy milk and thus have more offspring. What is even more strange is that, according to these studies, he already had a genetic predisposition to coronary heart disease and atherosclerosis. Even though he was not overweight (50 kg at 153 cm height), he certainly ran and stood more than he sat, he was quite young by our standards - 45-53 years old - and he kept a healthy and well-balanced diet (the last meal consisted of wild animal meat, roasted grains or flatbread, plant roots and fruit).

Of course, in 2012 and later, his possible origin or genealogy was genetically tested. The Y chromosome inherited from his father allowed him to be assigned to the most common haplogroup in South Corsica, although quite rare (G-L91). In 2013, the remains of probable relatives of the Iceman were found in Tyrol. Their common ancestor was supposed to have lived about 10-12 thousand years ago, although Ötzi himself could have died some 5,300 years ago. Research on the mtDNA inherited from the distaff side showed that our hero's mother belonged to a previously unknown European branch of the K1 haplogroup, which is difficult to find today. This research, especially later approaches to autosomal DNA (that is, everything we have in the genome that is not XY sex chromosomes or mtDNA), would show that Ötzi originated from a migration out of Anatolia to Europe in the 7th millennium B.C., when farmers replaced a population of earlier, European hunter-gatherers. Moreover, a solid admixture of the most common European DNA today, namely Indo-European, was found in it, to which I will return in a moment.

That’s all when it comes to the history of research. Nevertheless, over the last decade, there has been a rapid increase in modern and archaic DNA sequence databases, which allows us to determine relationships much more precisely. In addition, current methods of archaic DNA sequencing enable more accurate verification of genetic characteristics. What's more, they screen out possible contamination with contemporary DNA. Nucleic acids chemically age, so researchers separate from the mass of data only those sequences where this chemical marker of archaicity is found and further analyse only them. Sometimes, they constitute just a small percentage of all obtained sequences. The old DNA simply breaks down over time, so even a small admixture of modern human epidermis adds much more high-quality DNA to the sequence than even a very abundant sample from a prehistoric tooth. Therefore, to overcome this puzzle, scientists must sequence a lot of archaic material.

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  Despite these problems, Professor Krause's team from Leipzig University obtained almost the entire Ötzi genome, which was very good quality. The authors of the "Cell Genomics" journal publication note that unlike previous research, they did not find any "steppe" origin in the Iceman organism. What the researchers had in their mind was the previously recalled gigantic migration to Europe - about five thousand years ago - from the Pontic steppes and further Asian regions. This is how the people called today Proto-Indo-European - due to the language they spoke - came into being, e.g. the Yamnaya and the Corded Ware culture community. Ötzi turned out to have nothing in common with the 19 relatives found in Tyrol who were supposed to inherit the axe, the knife and the backpack (oh well, it’s nothing to laugh about; many would like such an inheritance, wouldn’t they?).

As geneticists from Leipzig further argue, "he has retained rather the highest percentage of ancestry from Anatolian-agricultural migration, common among modern European populations" (i.e. 92 percent! - today most of this DNA is found in the indigenous inhabitants of Sardinia, approximately 50 percent). That "indicates a rather isolated Alpine population with limited gene flow from populations related to hunters, gatherers and their own ancestors". Here we learn that the ancestors of the Iceman came - not only "to a large extent", but in a direct line – from the migration to Europe out of what is central Turkey now (earlier by some 2-3 thousand years from the arrival of the Proto-Indo-Europeans). Thanks to this, agriculture appeared in Europe because these Anatolians, with seeds and tools in hand - that is, with a gigantic achievement of civilisation - began to wander, and over time, they spread throughout our continent. Eventually, they began interbreeding with the existing, probably much more primitive in their eyes, native hunter-gatherer population.

As we can see from the studies of Ötzi's genome, he lived already at the time of quite aggressive Proto-Indo-European migration - perhaps this is where the hole from the arrow in his back comes from, which definitely killed him. However, there was still an isolated enclave of people in Tyrol, of which there is no trace today. Neither archaeological nor genetic. This means that the Alps were a genetic barrier.

Finally, we can read about something that is most striking. “Phenotypic analysis indicated that the Iceman probably had much darker skin than modern Europeans and carried risk alleles associated with male pattern baldness, type 2 diabetes and obesity-related metabolic syndrome. These results are supported by phenotypic observations of the preserved mummified body, such as high skin pigmentation and lack of hair on the head". Therefore, without a doubt, the statue of Ötzi in the Tyrolean museum will have to be changed. He will be dark-skinned, dark-eyed and bald. Paradoxically, the results coming from Krause's team research are much less inconsistent with the appearance of mummified corpses than the previous genetic tests, especially Ötzi's wax figure. The man with abundant hair, fair complexion and hazel eyes is an item from the memory store and a thing of the outdated past. "It's amazing how the reconstruction is influenced by our own prejudice about a Stone Age man from Europe," sums up Prof. Krause on the phys.org website.

– Magdalena Kawalec-Segond

TVP WEEKLY. Editorial team and jornalists

– translated by Katarzyna Chocian


Source: https://www.cell.com/cell-genomics/fulltext/S2666-979X(23)00174-X