The results of the analyses including additional ancient genomes provide mounting evidence that the Iceman's genetic affinity with Sardinians reflects an ancestry component that was widespread in Europe during the Neolithic. Despite their different geographic origins, both the Swedish farmer gok4 and the Thracian P192-1 closely resemble the Iceman in their relationship with Sardinians, making it unlikely that all three individuals were recent migrants from Sardinia. Furthermore, P192-1 is an Iron Age individual from well after the arrival of the first farmers in Southeastern Europe (more than 2,000 years after the Iceman and gok4), perhaps indicating genetic continuity with the early farmers in this region. The only non-HG individual not following this pattern is K8 from Bulgaria. Interestingly, this individual was excavated from an aristocratic inhumation burial containing rich grave goods, indicating a high social standing, as opposed to the other individual, who was found in a pit . However, the DNA damage pattern of this individual does not appear to be typical of ancient samples (Table S4 in ), indicating a potentially higher level of modern DNA contamination. On the other hand, the Swedish and the Iberian hunter-gatherers show congruent patterns of relatedness to the modern populations of Northern Europe, which is consistent with the previous results using those samples.Also of interest, given previous suggestions that the Iceman had more Neandertal ancestry than modern Europeans:
However, all D-tests involving another non-African population do not significantly deviate from zero, suggesting that the Iceman genome contains levels of archaic ancestry that are comparable to that of other non-African populations.
In any case, the fact that there are now data from Bulgaria is great, because it means that southern Europe is not hopeless for ancient DNA preservation and hopefully more is on its way.
UPDATE: Did anyone see a link to the new data? It appears that there are only ~1,000 SNPs in common with the HGDP. [A link to the data will become available at the Bustamante lab website]
PLoS Genet 10(5): e1004353. doi:10.1371/journal.pgen.1004353
Population Genomic Analysis of Ancient and Modern Genomes Yields New Insights into the Genetic Ancestry of the Tyrolean Iceman and the Genetic Structure of Europe
Martin Sikora et al.
Genome sequencing of the 5,300-year-old mummy of the Tyrolean Iceman, found in 1991 on a glacier near the border of Italy and Austria, has yielded new insights into his origin and relationship to modern European populations. A key finding of that study was an apparent recent common ancestry with individuals from Sardinia, based largely on the Y chromosome haplogroup and common autosomal SNP variation. Here, we compiled and analyzed genomic datasets from both modern and ancient Europeans, including genome sequence data from over 400 Sardinians and two ancient Thracians from Bulgaria, to investigate this result in greater detail and determine its implications for the genetic structure of Neolithic Europe. Using whole-genome sequencing data, we confirm that the Iceman is, indeed, most closely related to Sardinians. Furthermore, we show that this relationship extends to other individuals from cultural contexts associated with the spread of agriculture during the Neolithic transition, in contrast to individuals from a hunter-gatherer context. We hypothesize that this genetic affinity of ancient samples from different parts of Europe with Sardinians represents a common genetic component that was geographically widespread across Europe during the Neolithic, likely related to migrations and population expansions associated with the spread of agriculture.