Monday, September 8, 2014

Population Bust Late Neolithic - Study

Reconstructing regional population fluctuations in the European Neolithic using radiocarbon dates: a new case-study using an improved method Journal of Archaeological Science , Timpson et al, 2014 [Link]






It seems this paper is an attempt to bat down critics of 1.0 with an expanded timeframe from 10k to 4k bp.  It cover almost 14,000k dates in 12 regions that mostly show a bust pattern after the Early Neolithic. 

What I find interesting is that there are catastrophic declines in Europe throughout the third millennium, even after the arrival of Bell Beakers in the relevant regions.  Of course, dates end at 2,000 B.C., which is frustrating and very relevant for this blog.  I would imagine an increase occurred everywhere after this date.

There is, however, a massive population spike with the arrival of Maritime Bell Beakers in Bohemia and Moravia.  The population of Britain more than doubles and the population of Ireland nearly quadruples with the arrival of Beakers (1.0 paper).  The population of the Czech Republic almost triples and quadruples at the end of the millennium.

Putting this in context is more interesting.  It's not surprising to see the population of Britain expanding during this time, as it would appear to have been the subject of ongoing Beaker immigration from everywhere (Iberia, Lower Rhine and Central Europe). 

However, the Moravian and Bohemian numbers are simply jaw dropping.  Not only did it defy the continental trend from the sampled areas, it was likely the baby factory that sent immigrants to other parts of Europe, such as Little Poland, Hungary and Wessex.  So it wasn't just 3-4 times expansion.

It's also worth pointing out that the longevity and infant mortality estimates of several of the Moravian and Bohemian cemeteries are almost unrealistically modern.  Beakers in this region appear to have lived long and healthy lives.  To me this indicates the early establishment of political stability and rule of law. 

Abstract
In a previous study we presented a new method that used summed probability distributions (SPD) of radiocarbon dates as a proxy for population levels, and Monte-Carlo simulation to test the significance of the observed fluctuations in the context of uncertainty in the calibration curve and archaeological sampling. The method allowed us to identify periods of significant short-term population change, caveated with the fact that around 5% of these periods were false positives. In this study we present an improvement to the method by applying a criterion to remove these false positives from both the simulated and observed distributions, resulting in a substantial improvement
to both its sensitivity and specificity. We also demonstrate that the method is extremely robust in the face of small sample sizes. Finally we apply this improved method to radiocarbon datasets from European regions, covering the period 8000 to 4000 BP. As in our previous study, the results reveal a boom-bust pattern for most regions, with population levels rising rapidly after the local arrival of farming, followed by a crash to levels much lower than the peak. The prevalence of this phenomenon, combined with the dissimilarity and lack of synchronicity in the general shapes of the regional SPDs, supports the hypothesis of endogenous causes.

13 comments:

  1. It is now quite well established that after first wave Neolithic demicly replaces European hunter-gathers, that there is another round of migration driven major population genetic disruption in the European gene pool. It is also well established that this happens by the end of the Bronze Age with Iron Age population genetics closely resembling modern population genetics absent some isolated exceptions that prove the rule.

    We also know the population genetic character of the mid-Neolithic disruption in which G2a is replaced by R1b in the West and R1a in the East as the dominant Y-DNA haplogroup, and mtDNA haplogroup H becomes much more prominent in Europe.

    Early interpreters ascribed that to Indo-European transition which made lots of sense but didn't explain, for example, how the Basque who are certainly pre-Indo-European could have population genetics that exemplify the post-Neolithic population genetic transition in Western Europe.

    The Bell Beakers are in the right place at the right time in Western Europe and have ancient DNA that is a fit, albeit a tenuous one. But, this study seems to push the transition to the late Bronze Age in most of Europe and it seems odd that the Bell Beakers would have such a powerful demic impact with such a seemingly modest archaeological footprint of transition. Does this study tip the balance back towards early Indo-Europeans rather than Bell Beaker as the source of the population genetic transition in Europe due to its late timing?

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  2. Another complicating factor is that while we have lots of first wave Neolithic ancient DNA from the LBK farmers, today traced back to Romania, and along the Southern European coast (Cardial Pottery), we have little ancient DNA from the first farmers of the Atlantic and Baltic coasts of Western and Northern Europe where the Megalithic movement preceded Bell Beaker. Could Y-DNA R1b and mtDNA H have been present in the first rather than the second waves of farmers in these regions? These regions extend beyond the LBK or CP cultures proper, but it would be somewhat surprising if they were derived from some other early Neolithic population.

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    1. This is a good question for mtdna H. Channel Ware & La Almagra are big question marks since they may have come from North Africa. The question is how much of the Western Megalithic ancestry came from North Africa and what did that consist of.

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  3. "the Moravian and Bohemian numbers are simply jaw dropping".

    Hmmm... Are they really that notorious? There is growth followed by plateau in both regions since c. 2500 BCE but not that striking when we compare with England+Wales-Wessex or (from the previous version) Ireland. It is hard to decide also if this growth should be attributed to BB or to Corded Ware (which preceded the former by little). It is more similar to what happened in Central Germany (previous paper) and hence I would rather relate it to the quasi-contemporary Corded Ware + Unetice ethno-cultural phenomenon, at least partly.

    Today's genetics in those areas are clearly Eastern European (R1a dominates) and not Western-like, a trend that arguably can be tracked back (in Germany) to Indoeuropeanization (via mtDNA), while BB seems rather a "Westernizing" influence (high mtDNA H) in striking opposition to the former (very different mtDNA pools).

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    1. The two were definitely mixing here, don't know what that mix looked like. However, I would suspect that either side of the Elbe was more Beaker male mediated for the reason that the Corded Lineages don't seem to appear in places influenced by this area, especially the Southwest.

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  4. There were actually two major genetic shifts across much of Europe after the Neolithic.

    First, during the Copper Age, there was a shift to the east, which included the revival of hunter-gatherer mtDNA haplogroups like U2e, U4 and U5a, and this probably happened thanks to spread of the Corded Ware and related groups.

    Then, during the Bronze and Iron Ages, there was a shift to the west, with the frequencies of mtDNA H across most of the continent increasing to modern European levels. It's difficult to say what actually happened at this time, but my guess is that the populations that were growing and expanding the most were the hybrid Corded Ware/Bell Beaker groups, who had some sort of social/technological edge over everyone else.

    By the way, both tooth morphology and mtDNA suggest that Unetice groups in Central Europe were not direct descendants of German and Czech Bell Beakers. They were unusually Eastern European-like, even more so than Corded Ware groups studied thus far, and appear to be represent a fresh wave from somewhere in the east during the Bronze Age. I know this doesn't gel very well with archeological data, or at least the mainstream interpretations of it, but that's what the teeth and mtDNA indicate very strongly.

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    1. In disagreement, David. I think that the process was inverse or that they overlapped: that the Megalithic wave, which is clearly very strong in demographic terms (between c. 6000-4500 BP in Atlantic Europe), according to this and the previous similar study, was probably the most important force in reshaping the genetic pool of much of Europe and that the Bell Beaker phenomenon (less intense) is and aftershock of this one. Both BB and Corded Ware had much less of an impact, except BB in the Islands (notably Ireland).

      In other areas like Eastern Sweden we should think on other actors like Pitted Ware. In Central Europe the changes are complex and require regionalized analysis and probably Corded Ware played some role, especially in the East.

      But in no case you need to resort to Western influence in the Bronze Age, because there are clear demic explosions in relation to Megalithism and there are no West-originated archaeological expansions in the Bronze Age (unless you consider Urnfields, which originated at the Rhine, to be "Western"). It's indeed possible that Urnfields and its successors had some final say on the reorganization of the European genetic pools but they are not the Western genetic influence: that one must be older (and almost certainly was: Atlantic Neolithic + Megalithism + BB).

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  5. Here's a long reply to paragraph 3

    Some apparent influence comes from the lower Danube (Nagyrev culture (hungry, romania, balkans)) for Unetice, but I think this is mostly exotica moving up the Danube in late Beaker. Beaker stuff in Serbia, Greece, Romania, etc, is probably the stuff they exported, although a migration or trading colonies either way can't been excluded in this region.
    So I view the Unetice 'style' and a 'potential new elite' as two separate issues since they may have drawn on different origins.

    As far as the introduction of a new elite (genetics), here's two possibilities:

    One is that when the Atlantic Beaker networks began devolving, the importance of status goods coming through the Carpatho-Balkan region became increasingly important. The changes in southwestern Iberia may be evidence that NW Europe was becoming cut-off to the rest of the world. The increasing importance of Wessex may be evidence that islands were trading more heavily with Central Europe. In particular, Cornwall tin and Irish gold turn up 'notably' in Poland, which probably had cash over fist from the amber road.

    With the increase in mito-lineages you mention, I would suggest that NW Poland or the lower Danube could have been sources, but I think the centrality and wealth of Western Poland in the Unetice make it a better candidate (excluding the U2 lineage)

    Of course an external Asian influence is more than possible, but they would have adopted most aspects of Unetice culture instead of bringing it. Overall, mostly continuity IMO but potentially a new aristocracy. Can you link that dental study?

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    1. Essentially what we're seeing from the mtDNA and now also genome-wide data is a large scale movement during the Copper Age from the steppe and forest steppe into Central Europe, including Poland, resulting in a major shift of Central European genetics to the east, along with a revival of indigenous European ancestry, at the expense of the more Near Eastern-like genetic structure of the descendants of the Neolithic farmers. More info here...

      http://eurogenes.blogspot.com.au/2014/09/corded-ware-culture-linked-to-spread-of.html

      http://eurogenes.blogspot.com.au/2014/06/coming-soon-genome-wide-data-from-more.html

      http://eurogenes.blogspot.com.au/2014/04/the-really-old-europe-is-mostly-in.html

      From the data we have available, the Unetice culture was definitely part of this more European-like complex spreading out from the east during the late Neolithic/early Bronze Age, and helping to make Europeans less Near Eastern.

      But then came the Bell Beaker influence, shifting everything west and, from that complex mixture, helping to create the modern European gene pool.

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  6. R1b BB bringing LP to the Atlantic coast?

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    1. "Bringing" from where? The typical LP allele in Europe is dominant precisely in Atlantic Europe, not to the East, where other less known alleles with similar effect surely exist (Italians or Hungarians have more LP phenotype that this allele could explain).

      One thing we know of Neolithic Britain and Ireland is that the islands quickly switched from an HG diet rich on fish to a farmer diet with heavy milk participation (which remained as such until the Medieval Viking conquest). That almost necessarily implies that the farmers who colonized Britain c. 4000 BCE (from NW France and Brittany) were lactose tolerant.

      → http://forwhattheywereweare.blogspot.com/2014/02/neolithic-peoples-from-britain-and.html

      Also, in the Southernmost Basque Country, Chacolithic farmers have been "caught in the act" of initial mixing two different populations: one with the dominant Western European allele for LP and another lacking it, with almost no heterozygous individuals underlining the existence of these two "segregate" populations.

      → http://forwhattheywereweare.blogspot.com/2012/01/caught-in-act-lactose-intolerant-and.html

      All this must be considered when interpreting the expansion of the dominant LP allele in Europe.

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  8. Mike Baillie ( Exodus to Arthur ) shows that there was a 9 year "nuclear winter" from 2354BC to 2345BC, when tree growth throughout the whole world was severely impaired.
    Although Archaeologists shun his cometary theories, this is a dendrochronological fact, and I think this sort of climatic event would have an effect on human populations. This figure of around 2350BC is showing up as a hiatus at many sites throughout Europe.

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