Tuesday, April 23, 2024

Old News: The Spread Of The Neolithic Revolution In Europe

This map from 2006 has largely withstood the test of time. 

Some key observations that might otherwise be forgotten or overlooked:

* The initial Fertile Crescent Neolithic saw different crops and animals domesticated by genetically distinct modern human populations in different places across the Fertile Crescent. The Neolithic Revolution only expanded once the domesticated plants and animals found at various locations within the Fertile Crescent were consolidated into a single combined package of domesticates. 

* The European Neolithic revolution shared a common origin from Western Anatolia, to the Acreamic Neolithic in Crete, to Thessalia in Greece, to the rest of Greece and the Balkans, before forking off into Mediterranean and terrestrial European branches. The Fertile Crescent Neolithic package added some secondary domesticates in the process of this shared early expansion.

* The Western Mediterranean Neolithic (a.k.a. Cardial Pottery), was several centuries earlier than the early LBK (a.k.a. Linear Pottery) Neolithic in central Europe.

* The LBK Neolithic in central Europe started off in only the best land for farming, mostly along major rivers, and then expanded later into arable, but less optimal farming land.

* There was a mass migration of herders derived from the Mediterranean Neolithic the migrated along a narrow stretch of land, roughly in Eastern France, from Southern France towards central Europe at about the same time as the early LBK.

* As late as 4900 BCE large swaths of Europe had still not experienced the Neolithic Revolution and were still inhabited by European hunter-gatherers whose ancestors had migrated to Europe in the Mesolithic era.

* The Neolithic Revolution in Egypt, West Asia, and the Indus River Valley, were derived from the Fertile Crescent Neolithic Revolution as well, but are not shown on the map below.  These Neolithic expansions also picked up some secondary domesticated plants and animals along the way, like the donkey which was domesticated in Egypt. In Egypt, the Neolithic Revolution increased the population density in the Nile Basin by roughly a hundred-fold.

Source: Detlef Gronenborn, "Ancient DNA from the First European Farmers in 7500-Year-Old Neolithic Sites", 312 Science (June 30, 2006).

Monday, April 22, 2024

Two More Big Ancient DNA Papers

Eurogenes points out two more major European ancient DNA papers at bioRxiv (a pre-print server):

Germanic-speaking populations historically form an integral component of the North and Northwest European cultural configuration. According to linguistic consensus, the common ancestor of the Germanic languages, which include German, English, Frisian, Dutch as well as the Nordic languages, was spoken in Northern Europe during the Pre-Roman Iron Age. 
However, important questions remain concerning the earlier Bronze Age distribution of this Indo-European language branch in Scandinavia as well as the driving factors behind its Late Iron Age diversification and expansion across the European continent. 
A key difficulty in addressing these questions are the existence of striking differences in the interpretation of the archaeological record, leading to various hypotheses of correlations with linguistic dispersals and changes in material culture. Moreover, these interpretations have been difficult to assess using genomics due to limited ancient genomes and the difficulty in differentiating closely related populations. 
Here we integrate multidisciplinary evidence from population genomics, historical sources, archaeology and linguistics to offer a fully revised model for the origins and spread of Germanic languages and for the formation of the genomic ancestry of Germanic-speaking northern European populations, while acknowledging that coordinating archaeology, linguistics and genetics is complex and potentially controversial. We sequenced 710 ancient human genomes from western Eurasia and analysed them together with 3,940 published genomes suitable for imputing diploid genotypes. 
We find evidence of a previously unknown, large-scale Bronze Age migration within Scandinavia, originating in the east and becoming widespread to the west and south, thus providing a new potential driving factor for the expansion of the Germanic speech community. This East Scandinavian genetic cluster is first seen 800 years after the arrival of the Corded Ware Culture, the first Steppe-related population to emerge in Northern Europe, opening a new scenario implying a Late rather than an Middle Neolithic arrival of the Germanic language group in Scandinavia. Moreover, the non-local Hunter-Gatherer ancestry of this East Scandinavian cluster is indicative of a cross-Baltic maritime rather than a southern Scandinavian land-based entry. 
Later in the Iron Age around 1700 BP [250 CE], we find a southward push of admixed Eastern and Southern Scandinavians into areas including Germany and the Netherlands, previously associated with Celtic speakers, mixing with local populations from the Eastern North Sea coast. 
During the Migration Period (1575-1200 BP [375-750 CE]), we find evidence of this structured, admixed Southern Scandinavian population representing the Western Germanic Anglo-Saxon migrations into Britain and Langobards into southern Europe. During the Migration Period, we detect a previously unknown northward migration back into Southern Scandinavia, partly replacing earlier inhabitants and forming the North Germanic-speaking Viking-Age populations of Denmark and southern Sweden, corresponding with historically attested Danes. However, the origin and character of these major changes in Scandinavia before the Viking Age remain contested. 
In contrast to these Western and Northern Germanic-speaking populations, we find the Wielbark population from Poland to be primarily of Eastern Scandinavian ancestry, supporting a Swedish origin for East Germanic groups. In contrast, the later cultural descendants, the Ostrogoths and Visigoths are predominantly of Southern European ancestry implying the adoption of Gothic culture. 
Together, these results highlight the use of archaeology, linguistics and genetics as distinct but complementary lines of evidence.

The north Black Sea (Pontic) Region was the nexus of the farmers of Old Europe and the foragers and pastoralists of the Eurasian steppe, and the source of waves of migrants that expanded deep into Europe. We report genome-wide data from 78 prehistoric North Pontic individuals to understand the genetic makeup of the people involved in these migrations and discover the reasons for their success. 
First, we show that native North Pontic foragers had ancestry not only from Balkan and Eastern hunter-gatherers but also from European farmers and, occasionally, Caucasus hunter-gatherers. 
More dramatic inflows ensued during the Eneolithic, when migrants from the Caucasus-Lower Volga area moved westward, bypassing the local foragers to mix with Trypillian farmers advancing eastward. People of the Usatove archaeological group in the Northwest Pontic were formed ca. 4500 BCE with an equal measure of ancestry from the two expanding groups
A different Caucasus-Lower Volga group, moving westward in a distinct but temporally overlapping wave, avoided the farmers altogether, and blended with the foragers instead to form the people of the Serednii Stih archaeological complex. 
A third wave of expansion occurred when Yamna descendants of the Serednii Stih forming ca. 4000 BCE expanded during the Early Bronze Age (3300 BCE). The temporal gap between Serednii Stih and the Yamna expansion is bridged by a genetically Yamna individual from Mykhailivka in Ukraine (3635-3383 BCE), a site of uninterrupted archaeological continuity across the Eneolithic-Bronze Age transition, and the likely epicenter of Yamna formation. 
Each of these three waves propagated distinctive ancestries while also incorporating outsiders during its advance, a flexible strategy forged in the North Pontic region that may explain its peoples’ outsized success in spreading their genes and culture across Eurasia.
Davidski at Eurogenes comments that:
All of these studies are very useful, but there are some problems with each of them. Indeed, I'd say that the authors of the Lazaridis and McColl preprints need to reevaluate the way that they use ancient DNA to solve their linguistic puzzles. Once they do that their conclusions are likely to change significantly.

I tend to agree and will flesh out this post later as time becomes available. 

As an aside, stylistically, I think that it is poor form to put footnotes and references in a journal article abstract. I omit them per my standard formatting standards linked in the sidebar, when I quote them at this blog.