A great day for West Eurasian deep prehistory thanks to ancient DNA! First with “Late Pleistocene human genome suggests a local origin for the first farmers of central Anatolia” (Feldman et al. 2018, preprint) and now with this unexpected and very surprising “Paleolithic DNA from the Caucasus reveals core of West Eurasian ancestry” (Lazaridis et al. 2018, preprint).
The earliest ancient DNA data of modern humans from Europe dates to ~40 thousand years ago, but that from the Caucasus and the Near East to only ~14 thousand years ago, from populations who lived long after the Last Glacial Maximum (LGM) ~26.5-19 thousand years ago. To address this imbalance and to better understand the relationship of Europeans and Near Easterners, we report genome-wide data from two ~26 thousand year old individuals from Dzudzuana Cave in Georgia in the Caucasus from around the beginning of the LGM. Surprisingly, the Dzudzuana population was more closely related to early agriculturalists from western Anatolia ~8 thousand years ago than to the hunter-gatherers of the Caucasus from the same region of western Georgia of ~13-10 thousand years ago. Most of the Dzudzuana population’s ancestry was deeply related to the post-glacial western European hunter-gatherers of the ‘Villabruna cluster’, but it also had ancestry from a lineage that had separated from the great majority of non-African populations before they separated from each other, proving that such ‘Basal Eurasians’ were present in West Eurasia twice as early as previously recorded. We document major population turnover in the Near East after the time of Dzudzuana, showing that the highly differentiated Holocene populations of the region were formed by ‘Ancient North Eurasian’ admixture into the Caucasus and Iran and North African admixture into the Natufians of the Levant. We finally show that the Dzudzuana population contributed the majority of the ancestry of post-Ice Age people in the Near East, North Africa, and even parts of Europe, thereby becoming the largest single contributor of ancestry of all present-day West Eurasians.
After a still very shallow look at the paper, I’ll gather my preliminary thoughts. First the things that were more or less expected (a few of them mentioned in this previous post and the rest in other places) and that are more or less confirmed by these samples:
- Basal Eurasian is in a way (or all the way) not part of the main Out of Africa, if we understand the latter as the people who ventured into Eurasia and mixed with Neanderthals in the Near East before spreading throughout the rest of Eurasia. In contrast, Basal Eurasians split from this population before, and whether they were geographically located somewhere in North or East Africa, or deep down the Arabian Peninsula is still unknown, but it all indicates that they probably lacked Neanderthal admixture.
- This Basal Eurasian admixture appeared in the Near East before 26K YBP, since it’s already present in these Dzudzuana samples. The people with whom they mixed where what we’ve been calling Unknown Hunter Gatherers (UHG), the direct ancestors of the WHG found in Europe from the late UP.
- Since these UHG that entered Europe didn’t carry this Basal Eurasian admixture, this means that they must have moved out of the Near East before 26K YBP. The samples we have from Europe prior to the LGM go down to 25K YBP and these UHG/WHG have not been detected. This means that they were still not widespread at that time. However we already see admixture from them in El Miron, a sample from North Iberia ca. 18K YBP, which again confirms that the time of arrival must have been prior to the LGM (expanding from the Balkans or near after the LGM).
- Natufians seem to have some other kind of (North?) African admixture that post-dates the Basal Eurasian one.
- Finally, ANE again gets more support from having some sort of ENA admixture.
And now for what was less expected:
- ANE was still not present in the Caucasus by the time of these samples. We knew that this admixture came from further east (first sample we have is MA-1, from Lake Baikal in southern Siberia ca. 24K YBP).
- This, together with the likelihood of ANE/ENA contacts raises the question of the origin of ANE. Did these contacts happen in Siberia? Or did they happen in SC Asia? This is still an unknown issue, but I’ll try comment further on it tomorrow.
I’m sure there are a lot more things to comment from this (and the Anatolian HG) paper(s), so stay tuned and share your thoughts!