Sunday, March 28, 2021

Tales from the Supp. (Booth et al, 2021)

Booth et al, 2021 drill down to a greater time-scale resolution of the genetic turnover in Early Bronze Age Britain (~94%).  Was it a chainsaw massacre or was it a lengthy and complex process?

This paper looks at the 101 C-EBA Olalde samples over time, and adding the archaeological lens, conclude that the Beaker genetic ascendancy was more gradual than sudden, perhaps taking several hundred years.  This means Neolithic genetic enclaves probably persisted to some degree before succumbing to marital annihilation.  (marital not martial - although some married people might claim otherwise)

There's really three major issues this paper looks at with regards to popular interpretation of Britain's transformation.  The initial decrease of the Neolithic stock, which current data shows was rather sudden than an attenuation of Neolithic ancestry over time as the "younger sons hypothesis" would predict.  With that, the lack of a gradual increase in Neolithic ancestry among Beakers for several centuries.  And eventually, a small but significant increase in some sort of Neolithic ancestry which would almost need to be local.  This last point is especially important because it would taken an invasion of people with significant Neolithic ancestry to reverse the shift in a Chalcolithic wipeout scenario.

Barrow at Normanton Down, Wilshire (Historic England)

- They counter the notion of Kristensen and others that demographic change around Europe was mostly effected by bands of exogamous, un-landed warriors (younger sons) who took local wives wherever they went.  (and I will clarify a difference between patrilocality with exogamous female mobility and exogamy based on highly mobile (conquering) males).  And yet, it would seem based on the analysis of British genetic-genealogies from Olalde, British Beakers intermarried a lot less frequently than we might expect, at least initially.

- The selection of remains sampled for testing may have been biased towards crouched inhumations which reflect the dominant burial practice of Beakers.  And that it is possible, if not likely, that cremations (the dominant burial method of the British Neolithic) or burials in more marginal areas were less represented in the EBA genetic landscape, hiding in a sense, the full population demographic.  Booth et al further remark about the resurgence in Neolithic ancestry as testimony to this possibility.  

And while they concede that surging Neolithic ancestry could be coming from France or other places in the continent, essentially confirming a Chalcolithic wipeout scenario, the current genetic analysis may have difficulty distinguishing between Neolithic ancestry native to the Isles and those of France (for example).  (This is a question that might be resolved even without trying to test British cremated remains if, for example, the affinities of MLBA British Neolithic ancestry can be more accurately placed.  

- One of the main problems for British archaeologists with a wipeout scenario has been the fact that Neolithic traditions "appear" to be carried forward in the Beaker Age, suggesting at least some continuity.  The ~94% figure seems rather severe for the degree of influence from less than 10% of a marginalized population.  Whereas the repurposing of monuments may be entirely the work of immigrant Beakers, food vessels are another story.  So the Neolithics may not have been exterminated or genetically flooded in Britain as the numbers initially suggest.  A situation may exist where Neolithics were concentrated into genetic enclaves, such as Southern Ireland or the Irish Sea, to re-emerge if only slightly.

- Although they question the idea of mounted warriors lopping heads off at full gallop, the fact that British Beakers seem so un-shifted for so long in their generations, seems a bit paradoxical.  If the immigration into Britain involved equal numbers of men and women, then that undercuts the need for landscape roasting and booty wives in a younger sons hypothesis.  

If the decrease in Neolithic numbers was more gradual than the numbers suggest, it may be that Beakers immigrated over a span of several hundred years diluting the British Neolithic stock which, as an increasingly mixed population, continued the invisible cremation practice.  Or, it could be the simple and cruel process of elite domination de-landing and marginalizing Neolithics, generation after generation.  And/or, maybe Beakers were more successful in raising large, healthy families.

Here's another possibility (my own), that the Beaker pastoral economy yielded so much more in dreary, rainy, grassy-fields-full-of-rocks, miserable Britain, so much more than molded grain stocks or pulling limp turnips from the ground by people forced onto more marginal and less improved landscapes.  

...but while male mobility is viewed as the result of activities such as warfare and trade, women are figured as passive objects of exchange in exogamous patterns of marriage (Frieman et al. 2019). Women, it is argued, moved as wives, while men moved as significant social agents. The language of nineteenth-century evolutionism is reflected in the image of young male war-bands whose aggressive, competitive actions reflect an innate drive to attain political and economic domination. We can call into question the double standards that pervade this difference in the interpretation of male and female mobility.

I don't know that this should be at odds with itself.  It is demonstrable that Beakers practiced patrilocality with female exogamy when they were settled (see Sjogren et al, 2019), while large numbers of men were definitely not settled throughout Europe.  Beaker settlers heading to Britain probably surveyed prospective territories at least a year or more in advance.  As company-sized units comprised of extended families, they would have been interested in land poorly defended or with weak claims.  Advanced parties of men would begin preparations building livestock cores, houses, wells, fences, etc.  Simply parachuting in to a new territory with women and small children would be suicide without physical security.  There in lies the paradox.  De-landing natives from prime real estate requires violence or the threat of violence. 

In fact, as Booth et al show, the genealogies of early Beakers don't show us a love-fest between the two peoples.  However, their main points are valid in that, while the end genetic result is clear, the true demographic landscape from C-EBA Britain probably has some missing folks.


"Large-scale archaeogenetic studies of people from prehistoric Europe tend to be broad in scope and difficult to resolve with local archaeologies. However, accompanying supplementary information often contains useful finer-scale information that is comprehensible without specific genetics expertise. Here, we show how undiscussed details provided in supplementary information of aDNA papers can provide crucial insight into patterns of ancestry change and genetic relatedness in the past by examining details relating to a >90 per cent shift in the genetic ancestry of populations who inhabited Chalcolithic and Early Bronze Age Britain (c. 24501600 BC). While this outcome was certainly influenced by movements of communities carrying novel ancestries into Britain from continental Europe, it was unlikely to have been a simple, rapid process, potentially taking up to 16 generations, during which time there is evidence for the synchronous persistence of groups largely descended from the Neolithic populations. Insofar as genetic relationships can be assumed to have had social meaning, identification of genetic relatives in cemeteries suggests paternal relationships were important, but there is substantial variability in how genetic ties were referenced and little evidence for strict patrilocality or female exogamy."

Tales from the Supplementary Information: Ancestry Change in Chalcolithic–Early Bronze Age Britain Was Gradual with Varied Kinship Organization

TJ Booth, J Brück, S Brace, I Barnes - Cambridge Archaeological Journal
… Similar shifts in ancestry have been iden- tified in other parts of Europe in
the third millen- nium BC around the same time as the Corded Ware and
Bell Beaker phenomena, and they have been interpreted as indicating …