Further Tales of the Family of the Iceman Come to Light
Just last week it became known that the Iceman (also known as Ötzi) was infected with the bacterium H. pylori when he was killed. Now, researchers looking at his mtDNA have pinpointed the origins of his mother, showing that she was from the Alps region.
When scientists mapped the Iceman’s Y chromosome in 2012, they discovered that his paternal line (G2a) is still present in modern populations in Europe. The first results surprised the researchers and led them to question if Ötzi was a first generation immigrant from Sardinia, however he was later placed as a local of Central Europe. Furthermore, when researchers compared his genes with Stone Age hunter gatherers found in Sweden and Iberia, an Iron Age man found in Bulgaria, and an ancient farmer from Sweden, they found that Ötzi was most similar to farmers found in Bulgaria and Sweden. But what about Ötzi’s maternal lineage?
This too has been analyzed, and in 2008, researchers said that his mitochondrial DNA (received from his mother) suggested that his maternal linage (known as K1f) was either extremely rare and there were not sufficient comparison samples in their study, or it had become extinct. Valentina Coia, a biologist at EURAC, explains further:
“The first hypothesis could not be ruled out given that the study considered only 85 modern comparison samples from the K1 lineage -- the genetic lineage that also includes that of Ötzi -- which comprised few samples from Europe and especially none from the eastern Alps, which are home to populations that presumably have a genetic continuity with the Iceman. To test the two hypotheses, we needed to compare Ötzi's mitochondrial DNA with a larger number of modern samples.”
The mummy of the Iceman. (Crystalinks)
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Thus, as Phys.org reports, the EURAC team joined with members of Sapienza University of Rome and the University of Santiago de Compostela, to try to find the answer. The study, ‘Whole mitochondrial DNA sequencing in Alpine populations and the genetic history of the Neolithic Tyrolean Iceman.’ was published online in the journal Nature on January 14, 2016.
In this study the researchers compared the mtDNA of Ötzi with samples from 1,077 individuals belonging to the K1 lineage, of which 42 samples originated from the eastern Alps. This recent comparison showed that “neither the Iceman's lineage nor any other evolutionarily close lineages are present in modern populations.” Their results seem to confirm the latter hypothesis - Ötzi's maternal genetic line has likely become extinct.
In the second part of the study, the researchers compared his mitochondrial DNA to data from other European Neolithic samples, looking for the origins of K1f. Their results from this analysis suggests that Ötzi's maternal lineage “originated locally in the Alps, in a population that did not grow demographically.” [Via EurekAlert!]
The next question for the researchers was why the K1f group died out while the G2a continues on today. Using the past and current research, they have proposed the following scenario:
“Ötzi's paternal lineage, G2a, is part of an ancient genetic substrate that arrived in Europe from the Near East with the migrations of the first Neolithic peoples some 8,000 years ago. Additional migrations and other demographic events occurring after the Neolithic Age in Europe then partially replaced G2a with other lineages, except in geographically isolated areas such as Sardinia. In contrast, the Iceman's maternal branch originated locally in the eastern Alps at least 5,300 years ago. The same migrations that have replaced only in part his paternal lineage caused the extinction of his maternal lineage that was inherited in a small and demographic stationary population. The groups from the eastern Alps in fact significantly increased in size only from the Bronze Age onwards, as evidenced by archaeological studies conducted in the territory inhabited by the Iceman.”
Sculpture of what Ötzi may have looked like when he was alive. (CC BY SA 3.0)
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Maps explaining the proposed scenario for K1f and G2a. Map A: Migrations occurred around 8,000 ybp of Early Neolithic people from the Near East to Europe carrying the main mtDNA (K1) and Y chromosome (G2a) haplogroups according to recent data on ancient DNA studies. Map B: Distribution of mtDNA K1 (circles) and Y chromosome G2a (rectangles) haplogroups in ancient samples dated > 5,000 ybp and their absolute frequencies. Map C: Distribution and approximate frequencies of haplogroup G2a-L91 in Europe. (V. Coia, et al.)
The continued studies on the Iceman lead one to wonder what further stories Ötzi's remains hold for the future, about the past.
Featured Image: The Iceman's hand. Source: South Tyrol Museum of Archaeology/EURAC/M.Lafogler
By: Alicia McDermott