Peeling away the past

David at Eurogenes points to me a list of abstracts for ISABS 2015. Three caught my attention, and I will share them.

First, THE FIRST GENOMIC DATA FROM ANATOLIA AND ITS IMPACTS ON EUROPEAN NEOLITHICS:

The most important process in the prehistory of our species is arguably the Neolithization. In the course of 10000 years, it took us from a hunter-gatherer lifestyle to the society we live in today. For Eurasia, Anatolia and the Near East played a key role in this process. It has already been shown that the neolithic expansion from this area and westwards was driven by migration. But we know little about the actual establishing of neolithic societies in Anatolia, and on what kind of population dynamics effected their gene pool. And we also know little more about the Neolithic gene flow from Anatolia than that it had occurred. For the first time we present genomic results from an ancient Anatolian farmer, from Troy’s proto-settlement Kumtepe, and it anchors the European neolithic genepool to Anatolia. Further, the late-neolithic individual from Kumtepe does not only contain the genetic element that is frequent in early European farmers, but also a component found mainly in modern populations from the Near and Middle East and Northern Africa, and to a much smaller degree, in some Neolithic European farmers. The scene presented by Kumtepe is compatible with geneflow into Europe from or through the neolithic core area in Anatolia. And it is likely that this occurred early, perhaps just after the neolithic core area had been established in southeastern Anatolia.

WHAT THE GENOMES OF EIGHT EARLY IBERIAN FARMERS TELL US ABOUT THE PREHISTORY OF IBERIA AND THE REST OF EUROPE:

The consequences of the Neolithic transition in Europe – one of the most important cultural changes in human prehistory – is a subject of intense study. However, the consequence of this transition on prehistoric and modern-day people in Iberia, the westernmost frontier of the European continent, remains unresolved. Here we present the first genome-wide sequence data from eight human remains, dated to between 5,500 and 3,500 years before present (Chalcolithic and Bronze Age), excavated in the El Portalón cave at the Sierra de Atapuerca, Spain. We show that these individuals emerged from the same ancestral gene pool as early farmers from other parts of Europe suggesting that migration was the dominant transfer-mode of farming practices throughout western Eurasia. Early farmers, including the El Portalón individuals, were found to have mixed with different local hunter-gatherers as they migrated to different parts of Europe and that the proportion of hunter-gatherer related admixture into farmers increased over the course of two millennia. Among all early farmers, the Chalcolithic El Portalón individuals show the greatest genetic affinity to Basques. These El Portalón genomes reveal important pieces of the demographic history of Iberia and Europe and advance our understanding of the relationship between hunter-gatherers and farmers, and how they relate to modern-day groups.

GENOMIC DIFFERENCES BETWEEN NEOLITHIC AND MESOLITHIC HUNTER-GATHERERS IN SCANDINAVIA:

Different origins of the late hunter-gatherers (HGs) of the Scandinavian Middle Neolithic (5300-4300 BP) Pitted Ware Culture (PWC) have been proposed. While many archaeologists advocate an ancestry in the preceding and partly contemporary farmers of the Funnel Beaker Culture (FBC) ancient genomic data show a strong genetic differentiation between these two groups. It has, in fact, been suggested from genome-wide capture data that PWC are the direct descendants of the Mesolithic HGs from Motala (Sweden) with no additional admixture from other populations. However, by reanalyzing published full genome sequence data from Ajvide (PWC), Gökhem (FBC) and Motala (Mesolithic HG) we gained higher resolution, and found previously unknown differences between Ajvide and Motala. First, Principal Component Analyses show that, even though Ajvide and Motala cluster together, Ajvide is closer to present-day European populations (and to early farmers). Second, D-tests show asymmetric relationships to other groups which would not be expected under a scenario of complete continuity. More specifically we show that i) Gökhem is closer to Ajvide than to Motala, ii) the Siberian Paleolithic HG MA1 is closer to Motala than to Ajvide, and iii) that the Central European Mesolithic HG Loschbour is closer to Ajvide than to Motala. These results indicate a more complex transition from Mesolithic to Neolithic HG societies in Scandinavia and the demographic implications will be discussed.

I believe that papers such as Massive migration from the steppe is a source for Indo-European languages in Europe probably give us a good idea about the details of how the genetic structure of northwest Eurasia came about. At least in the broad outlines. But there are curious details which need to be worked out and explicated. I ordered the abstracts above from the most easy to interpret to the least.

First, it does seem clear that the Middle East has changed a fair amount since the first farmers arrived in Europe. These first farmers were geographically Middle Eastern, but they were somewhat different from modern Middle Easterners. Attempts to use modern Middle Eastern populations as proxies from the first farmers gave us a false picture in part because modern Middle Eastern populations themselves are not fossils from the Neolithic. They’ve changed in situ. This is obviously a lesson we should have learned by now. Many populations are not what we think they are.

In particular this has been an issue for the Basques. About ten years ago I read something about Basque culture where the author casually mentioned that aspects of their language give clear evidence as to their origins as the last hunter-gatherers of Europe. We now know that this is probably wrong in many ways. Rather than being the purest distillation of the genetic variation of the hunter-gatherers of Europe (in fact, modern Northern Europeans seem to be genetically closer to hunter-gatherers who lived in the Iberian peninsula than modern Spaniards!), the Basque are likely descendants of one of the early waves of farmers into Europe (at least in large part, we should never forget that some amount of assimilation of the indigenous substrate occurred, especially early on). Earlier work used various genetic characteristics of Basques to assess how “hunter-gatherer” other populations were. The problem with that turns out to be that Basques themselves are not very hunter-gatherer in origin, at least in terms of being a population whose ancestors were mostly hunter-gatherers in Europe at the end of the last Ice Age.

The final paper is something that I really don’t have a good grasp of, or explanation for. But, I will say that Scandinavia is on the edge of the range of humans. Population densities in many areas (though not all) have been rather low for a long time. It is not implausible to me that you’d see lots of population extinctions and replacements over time, leading to a lot of confusing discontinuity.

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