Neolithic DNA from Greece and NW Anatolia and their influence on Europe

This is a most interesting study that brings to us potentially key information on the expansion of European Neolithic and the formation of modern European peoples.

Zuzana Hofmanová, Susanne Kreutzer et al., Early farmers from across Europe directly descended from Neolithic Aegeans. PNAS 2016. Open access → LINK [doi:10.1073/pnas.1523951113]

Abstract

Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.

Uniparental DNA

One of the most important findings is that the two Epipaleolithic samples from Theopetra yielded mtDNA K1c, being the first time in which haplogroup K has been detected in pre-Neolithic Europe. Sadly enough these two individuals could not be sequenced for full genome. 

The other five individuals are all Neolithic (three early, two late) and did provide much more information.

• Rev5 (c. 6300 BCE): mtDNA X2b
• Bar31 (c. 6300 BCE): mtDNA X2m, Y-DNA G2a2b
• Bar8 (c. 6100 BCE): mtDNA K1a2
• Pal7 (c. 4400 BCE): mtDNA J1c1
• Klei10 (c. 4100 BCE): mtDNA K1a2, Y-DNA G2a2a1b (same as Ötzi's)

I color coded their abbreviated names according to the usage in the study's many maps, for easier reference: green shades are for Greece (Western Macedonia), red shades for Turkey (Bursa district). It is also very convenient to get straight their real geography because many of the map-styled graphs are not precise at all about that:

Fig. 1.

North Aegean archaeological sites investigated in Turkey and Greece.

Autosomal DNA affinities

This is probably the most interesting part. There is a lot about it in the supplementary information appendix but I find that the really central issue is how they relate to each other (or not) and to other ancient and modern Europeans. I reorganized figs S21 and S22 to better visualize this:

Ancient samples compared to each other and other ancient samples ("inferred proportions of ancestry")

Ancient samples compared to modern Europeans ("inferred proportions of ancestry")

So what do we see here? First of all that the strongest contribution of known Aegean Neolithic peoples on mainline European Neolithic is from Bar31, which is from NW Anatolia, and not from Greece. Bar8 is a less important contributor but may have impacted particularly around the Alps (Stuttgart-LBK, modern North Italians).

This goes against most archaeology-based interpretations, which rather strongly suggest a Thessalian and West Macedonian origin of the Balcanic and, therefore, other European branches of the mainline Neolithic of Aegean roots, and do instead support some sort of cultural barrier near the European reaches of the Marmara Sea. Of course we lack exhaustive sampling of Greek Neolithic so far, so it might be still possible that other populations from Thessaly or Epirus could have been more important. However the lack of Anatolian-like influence on the Western Macedonian Neolithic until c. 4100 BCE, makes it quite unlikely.

So it seems that, once again, new archaeogenetic information forces us to rethink the interpretative theories based on other data.

However we do see a strong influence of Greek Neolithic and particularly the oldest sample, Rev5, in SW Europe, very especially among Basques, who seem to have only very minor Anatolian Neolithic ancestry, unlike everyone else relevant here. This impact is also apparent in Sardinia and to some extent North Italy (but overshadowed in these two cases by the one from Anatolia, particularly Bar31).

There are also similar analyses for other four ancient samples (Lochsbour, Stuttgart, Hungary Neolithic and Hungary Bronze) but they don't provide truly new information, so I'm skipping them here. As I said before, there's a hoard of analyses in the SI appendix, enjoy yourselves browsing through them and feel free to note in the comments anything you believe important.

A synthesis of the various "inferred proportions of ancestry" analyses is anyhow shown in fig. 3:

Fig. 3. (click to expand)

Inferred mixture coefficients when forming each modern (small pies) and ancient (large pies, enclosed by borders matching key at left) group as a mixture of the modern-day Yoruba from Africa and the ancient samples shown in the key at left.

The fractions may be misleading however, especially for the ancients. For example: Lochsbour (a total outlier among the ancients in this study) appears best correlated with Pal7 but in fig. S24 it is clear that does no correlate with any Neolithic sample at any significant level. But in general terms it can give a good idea of where does ancestry, particularly for modern samples, come from.

Note: elsewhere someone was being a crybaby about the Polish sample (may well be an error) or the Kalmyk sample (who are obviously most related to East Asians, not used here) but those are minor issues.

Of course there's a lot more to learn from the remains of the ancients. Let's keep up the good work.