Neither hair nor white skin: tzi, the ice man of the Alps, was bald and had very dark skin

2023-08-16 17:04:59

He lived 5,200 years ago and his mummy was found in 1991

Updated Wednesday, August 16, 2023 – 17:02

Previous reconstructions showed a male with light skin, light eyes and quite a bit of hair, but a new analysis of his genome shows that he looked different, came from Anatolia and was prone to obesity and diabetes.

Just over thirty years ago, two hikers discovered the mummified remains of a prehistoric hunter on the shores of a lake in the Tztal Alps, on the border between Austria and Italy. Preserved naturally for 5,000 years by a unique combination of sun, wind, and freezing temperaturestzi’s corpse attracted the attention of the scientific community -and the public in general- due to the amount of information it can provide about European prehistory and the evolution of populations on the continent.

Also, a few years later, evidence of a violent death added a layer of mystery to the find of this Neolithic iceman. Since then, andtzi’s mummified body has been the subject of numerous studies that have allowed us to learn more about his life, his origin and the conditions of his death. Ace, we knew that tzi was slim, left-handed, about 160 cm tall, and about 46 years old at the time of his death. Her blood type was 0, she was lactose intolerant and carried a genetic abnormality that prevented the formation of her twelfth pair of ribs.

Carbon 14 dating revealed that tzi lived 5,200 years ago (3350-3110 BC) and died pierced by an arrowto. The first tests suggested that the original color of his eyes was blue, until a first analysis of his genome, just over ten years ago, described him as a Mediterranean-European type, with dark skin and dark eyes. Now a team of researchers has wanted to go even deeper, with a new genomic analysis applying advanced techniques. The results are published this Wednesday in the scientific journal Cell and show that tzi had an even darker complexion than previously thought and possibly had receding hairlines.

“Genome analysis has revealed phenotypic traits such as high skin pigmentation, dark eye color, and the pattern of a predisposition to male pattern baldness that contrast sharply with previous reconstructions, which show a light-skinned, dark-eyed male.” pale and quite hairy”, explains Johannes Krause, from the Max Planck Institute for Evolutionary Anthropology (Germany), co-author of the article. “It is curious how the first reconstructions were biased by the preconceived ideas of the Europeans during the Stone Age.”

“It is the darkest skin tone that has been recorded in contemporary European individuals”adds anthropologist Albert Zink, also a co-author of the study and director of the Eurac Research Institute for Mummy Studies in Bolzano. “It was previously thought that the mummy’s skin had darkened during its preservation in ice, but what we see now is actually largely the original skin color of tzi,” important information for proper mummy preservation. .

Genes for increased risk of obesity and type 2 diabetes were also found in tzi’s genome, although the researchers note that it was likely he never had such problems due to the constant activity. Throughout her life, tzi broke her nose and several ribs, and analysis of her fingernails indicates that she experienced several periods of great physical stress (probably due to malnutrition) in the months before her death. .

Origin in present-day Turkey

Analysis of tzi’s DNA further confirms that it didor genetic heritage comes from a population of Neolithic farmers who arrived from Anatolia to the center and west of the continent between 6,000 and 8,000 years ago, and that mixed with the hunter-gatherers that populated those regions.

In fact, several studies suggest that the genetic composition of most of today’s Europeans is mainly due to the mixture of three ancestral groups: on the one hand, hunter-gatherers who have been on the continent since the Paleolithic and gradually merged with the first farmers who migrated from Anatolia about 8,000 years ago; These would be joined approximately 4,900 years ago by a third group of steppe horsemen from the east.

In the case of the tzi, the authors have been surprised by the lack of diversity of its genetic inheritance, which owes more than 92% to its Anatolian ancestors, which, according to the researchers, shows that it hardly exchanged genes with the indigenous peoples. north and west of the Alps. In addition, initial analyzes of the genome had revealed genetic traces of steppe herders from the east, which the new results rule out. “We were very surprised to find no traces of eastern European steppe herders in the genome analysis; in the same way that the ratio of hunter-gatherers is also very low”, explains Johannes Krause, who points to contamination of the samples to explain the first results.

The researchers conclude that tzi came from a relatively isolated population and that the Alps could be a barrier to that genetic exchange. Even so, Krause points out that it is not clear if this Neolithic inhabitant is representative of its contemporaries on the continent and that to answer that question definitively, more studies are needed that analyze more individuals from the same region and time.