The uneasy relationship between Archaeology and Ancient Genomics

Allentoft Corded Ware

News feature Divided by DNA: The uneasy relationship between archaeology and ancient genomics, Two fields in the midst of a technological revolution are struggling to reconcile their views of the past, by Ewen Callaway, Nature (2018) 555:573-576.

Interesting excerpts (emphasis mine):

In duelling 2015 Nature papers6,7the teams arrived at broadly similar conclusions: an influx of herders from the grassland steppes of present-day Russia and Ukraine — linked to Yamnaya cultural artefacts and practices such as pit burial mounds — had replaced much of the gene pool of central and Western Europe around 4,500–5,000 years ago. This was coincident with the disappearance of Neolithic pottery, burial styles and other cultural expressions and the emergence of Corded Ware cultural artefacts, which are distributed throughout northern and central Europe. “These results were a shock to the archaeological community,” Kristiansen says.

(…)

Still, not everyone was satisfied. In an essay8 titled ‘Kossinna’s Smile’, archaeologist Volker Heyd at the University of Bristol, UK, disagreed, not with the conclusion that people moved west from the steppe, but with how their genetic signatures were conflated with complex cultural expressions. Corded Ware and Yamnaya burials are more different than they are similar, and there is evidence of cultural exchange, at least, between the Russian steppe and regions west that predate Yamnaya culture, he says. None of these facts negates the conclusions of the genetics papers, but they underscore the insufficiency of the articles in addressing the questions that archaeologists are interested in, he argued. “While I have no doubt they are basically right, it is the complexity of the past that is not reflected,” Heyd wrote, before issuing a call to arms. “Instead of letting geneticists determine the agenda and set the message, we should teach them about complexity in past human actions.”

Many archaeologists are also trying to understand and engage with the inconvenient findings from genetics. (…)
[Carlin:] “I would characterize a lot of these papers as ‘map and describe’. They’re looking at the movement of genetic signatures, but in terms of how or why that’s happening, those things aren’t being explored,” says Carlin, who is no longer disturbed by the disconnect. “I am increasingly reconciling myself to the view that archaeology and ancient DNA are telling different stories.” The changes in cultural and social practices that he studies might coincide with the population shifts that Reich and his team are uncovering, but they don’t necessarily have to. And such biological insights will never fully explain the human experiences captured in the archaeological record.

Reich agrees that his field is in a “map-making phase”, and that genetics is only sketching out the rough contours of the past. Sweeping conclusions, such as those put forth in the 2015 steppe migration papers, will give way to regionally focused studies with more subtlety.

This is already starting to happen. Although the Bell Beaker study found a profound shift in the genetic make-up of Britain, it rejected the notion that the cultural phenomenon was associated with a single population. In Iberia, individuals buried with Bell Beaker goods were closely related to earlier local populations and shared little ancestry with Beaker-associated individuals from northern Europe (who were related to steppe groups such as the Yamnaya). The pots did the moving, not the people.

This final paragraph apparently sums up a view that Reich has of this field, since he repeats it:

Reich concedes that his field hasn’t always handled the past with the nuance or accuracy that archaeologists and historians would like. But he hopes they will eventually be swayed by the insights his field can bring. “We’re barbarians coming late to the study of the human past,” Reich says. “But it’s dangerous to ignore barbarians.”

I would say that the true barbarians didn’t have a habit or possibility to learn from the higher civilizations they attacked or invaded. Geneticists, on the other hand, only have to do what they expect archaeologists to do: study.

EDIT (30 MAR 2018): A new interesting editorial of Nature, On the use and abuse of ancient DNA.

See also:

The myth of mixed language, the concepts of culture core and package, and the invention of ‘Steppe folk’

neolithic-steppe

I recently read some papers which, albeit apparently unrelated, should be of interest for many today.

Mixed language

The myth of the mixed languages, by Kees Versteeg, in Advances in Maltese linguistics, ed. by Benjamin Saade and Mauro Tosco, 217-238. Berlin and New York: Mouton de Gruyter, 2017 [uncorrected proofs]

This paper focuses on the usefulness of the label ‘mixed languages’ as an analytical tool. Section 1 sketches the emergence of the biological paradigm in linguistics and its effect on the contemporary debate about mixed languages. Sections 2 and 3 discuss two processes that have been held responsible for the emergence of mixed languages, code switching and extreme borrowing. Section 4 compares these two mechanisms with the categories of change in Thomason & Kaufman (1988), while Section 5 offers some conclusions about the status of mixed languages as a special category.

Although the paper is a must read for language contact and language change (code-switching, borrowing, shifting), a good summary may save you some time if you are not interested in linguistics:

Speakers may either shift to a new language while retaining traces of their old language, or they may stick to their original language while borrowing from another language with which they come in touch (…)

[Bakker] distinguishes two types of communities in which mixing is found: isolated mixed marriage communities with (asymmetrical) bilingualism; and nomadic communities that shift to a dominant language, but retain a substantial part of their lexicon as a private or secret register, closely connected with the community’s identity. The history of these communities provides us with plausible scenarios to explain the idiosyncrasies of the speech pattern of the speakers belonging to them.

In what way, then, does it help to put both categories under one label of mixed languages? I believe Backus (2003: 263) is right when he suggests that the question of whether a certain set of features constitutes a mixed language is perhaps not a very interesting one. The question should not be whether given certain features a language may be categorized as mixed, but what the linguistic effects of different kinds of contact (trade, work, conquest, mixed marriages, colonization, marginalization, etc.) are, and to what extent these effects correlate with the type of contact. At no point is it necessary to posit a category of mixed languages. In fact, the myth of the mixed languages may have been perpetuated because of the relative weirdness of the initial cases, notably that of Michif, which represent phenomena so unique that it is understandable that some scholars came to believe that they could only be explained by special mechanisms. The position taken here is that if we focus on the speakers’ behavior, the phenomena in question become much more understandable. The crucial point is that languages do not mix, people do.

Culture core and package

The article Isolation-by-distance, homophily, and “core” vs. “package” cultural evolution models in Neolithic Europe, by Shennana, Crema, and Kerig (2015):

Recently there has been growing interest in characterising population structure in cultural data in the context of ongoing debates about the potential of cultural group selection as an evolutionary process. Here we use archaeological data for this purpose, which brings in a temporal as well as spatial dimension. We analyse two distinct material cultures (pottery and personal ornaments) from Neolithic Europe, in order to: a) determine whether archaeologically defined “cultures” exhibit marked discontinuities in space and time, supporting the existence of a population structure, or merely isolation-by-distance; and b) investigate the extent to which cultures can be conceived as structuring “cores” or as multiple and historically independent “packages”. Our results support the existence of a robust population structure comparable to previous studies on human culture, and show how the two material cultures exhibit profound differences in their spatial and temporal structuring, signalling different evolutionary trajectories.

Our results suggest distinct evolutionary histories in the spatial and temporal variation of personal ornament and pottery, with different rates of innovation, patterns of descent, and dynamics of diffusion. Ornament data do show statistically significant values of ΦST using pottery-defined population structures, but the magnitude is extremely small, and partial Mantel tests suggest that much of this pattern is explained by isolation by distance. These results are in line with a model
of culture represented by independent “packages” of multiple coherent units rather than one characterised by a distinct and fairly isolated “core” surrounded by a “periphery” of elements prone to crosscultural transmission. The alternative hypothesis is that one element was part of the “core” tradition, whilst the other was peripheral. This scenario is however less likely given that both elements are generally regarded as expression of local lines of transmission and/or signalling.

The robust support for a population structure in the pottery data shows that some degree of homophily must have biased the transmission process, but this bias was confined within the single “package”, rather than affecting other aspects of the material culture. In other words similarity (or dissimilarity) of pottery style was not influencing the transmission process of personal ornaments and vice-versa. If this was the case, we should have observed a stronger agreement between in the spatio-temporal distribution of the two datasets, a pattern we failed to observe. Personal ornaments are often seen as group-identity markers, but the fact that our study appears to indicate a stronger role for isolation by distance in accounting for variation in ornaments suggests that this assumption may not be valid, or alternatively that these groups cross-cut the archaeological cultures traditionally recognised. Thus,while our study has provided strong evidence of population structure affecting patterns of cultural interaction, in this case at least the distinct patterns observed point to a modular, ‘package’ model. It has also shown that we can identify population structuring from the evidence of the archaeological record without continuing to attempt the fruitless task of correlating its patterns with past ethnolinguistic units.

pottery-ornament-neolithic-europe
Location of material culture (ornament and pottery) data of 361 Neolithic sites in central
Europe

A situation more interesting than Neolithic Europe for those following this blog will probably be the one on West Europe during the Bell Beaker expansion.

Regarding Iberia, I have already talked about the possibilities of “resurgence” after the arrival of Bell Beaker migrants, in this blog and in the Indo-European demic diffusion model.

About the British Isles, you can read e.g. the stepped and different cultural changes that happened after the arrival of East Bell Beakers in What was and what would never be: changing patterns of interaction and archaeological visibility across north-west Europe from 2,500 to 1,500 cal BC, by Wilkin, N., Vander Linden, M. 2015. In : Anderson-Whymark, H., Garrow, D., Sturt, F. (eds)Continental connections. Exploring cross -Channel relationships from the Mesolithic to the Iron Age. Oxford: Oxbow: 99-121.

britain-ireland-bell-beaker
The changing cultural geography of north-west Europe c. 3000-1500 BC. Solid line: architecture; dashed line: material culture;, dash-dot line: funerary practices

This logical description different cultural changes brings up a question obvious to many, and can be summed up by “does the arrival of (North-West Indo-European-speaking) East Bell Beakers mean the end of non-Indo-European cultures in Western and Northern Europe?” The answer is obviously – as in the rest of Europe – quite simply No. Many non-Indo-European groups must have survived the initial expansion of East Bell Beakers in many regions, as the pre-Roman situation (already quite simplified after the expansion of Celtic and Germanic) testifies.

“Resurgence” of local groups as seen in genomic data is the most direct connection with survival of previous non-IE cultures (and thus languages), but obviously not the only mechanism of language survival, since we can see founder effects – such as those seen in modern Basque speakers (mainly of R1b subclades), and in Ugro-Finnic speakers in north-east Europe (mainly of N subclades).

Steppe folk

I am recently stumbling more and more often upon the concept of ‘Steppe people‘ by amateur geneticists, whether in Anthrogenica, in blogs and blog comments, or even in research papers, where people used to talk about ‘Yamnaya people’ or ‘Yamnaya folk’. As I said, I expected this since I questioned the concept of the ‘Yamnaya ancestral component‘, so I feel vindicated by this change.

However, whereas most will be using these names simply following the redeeming term “steppe admixture”, and thus refer to a Neolithic steppe population that shared a common admixture component (probably ca. 5000 BC), some will obviously go further and identify this component with Proto-Indo-European (like that, in general terms), since it is the logical sequence for those who consider the term “Indo-Europeans” as an umbrella for a certain ethnic proportion and a link with modern populations in stupid autochthonous continuity theories, where prehistoric language and culture are irrelevant.

NOTE. Evidently, those who supported quite strongly the fact that R1a-M417 subclades associated with Corded Ware migrants (i.e. mainly R1a-Z645) stemmed directly from Yamna migrants are shifting terminology to “steppe people” in light of recent data, so that they can support an older steppe community in the likely case that no R1a is found in Yamna, while keeping open the possibility to revert to a more direct support of the Yamna -> Corded Ware model in case just one R1a sample is found… So no anthropological model at all here, just a personal desire to be fullfilled in any possible way.

Those thinking naively about an imaginary ‘Steppe folk’, living in loosely connected steppe cultures, speaking a mixed ‘Steppe language’, may well keep inventing potentially popular peoples and languages based on admixture, such as West Hunter-Gatherer folk (Vasconic?), East Hunter-Gatherer folk (Uralic? – or maybe today they can invent a Siberian folk bringing Finno-Ugric after 500 BC), Caucasus Hunter-Gatherer folk (??), etc. So welcome back to the 1930s!… Or was it the 2000s?

wiik-modified
Image modified by me from Wiik’s original, for those of you nostalgic fans of autochthonous continuity theories: You can now again support a native Vasconic-Uralic-Indo-European “folk” distribution in Neolithic Europe.

Some people like to talk about how “Science” wins against Academia, especially when they try to defend this pseudo-subfield they are inventing and venerating on the go to characterize ancient populations, where new genomic methods are king, and the other fields involved are just noise they easily use or dismiss to support their own desires and preconceptions.

NOTE. I felt like many fans of Genomics are very well represented in this recent article at ArXiv: “23andMe confirms: I’m super white” — Analyzing Twitter Discourse On Genetic Testing

Too bad for them. The misuse of this new field might be popular today among certain amateur geneticists, but it will not stand the test of time, similar to how the initial hype around radiocarbon analysis (for Archaeology) or glottochronology (for Linguistics) eventually faded, and they became just another tool among traditional methods. In Science, time puts everything where it belongs.

Whether you like it or not, Indo-European (and Uralic) questions will be solved – as they have been for a long time now, there is nothing new under the sun – with Historical Linguistics first, then Prehistoric Archaeology, then Anthropology (models of migration, cultural diffusion, founder effects, etc.), and only then Genomics, which may (or may not) help solve certain controversial aspects, by supporting one or other anthropological model. Period.

See also:

We are all special, which also means that none of us is

Europe_around_800_Charlemagne

Adam Rutherford writes You’re Descended from Royalty and So Is Everybody Else – Anybody you can name from ancient history is in your family tree, which I discovered via John Hawks’ new post The surprising connectedness of human genealogies over centuries.

Excerpt:

One way to think of it is to accept that everyone of European descent should have billions of ancestors at a time in the 10th century, but there weren’t billions of people around then, so try to cram them into the number of people that actually were. The math that falls out of that apparent impasse is that all of the billions of lines of ancestry have coalesced into not just a small number of people, but effectively literally everyone who was alive at that time. So, by inference, if Charlemagne was alive in the ninth century, which we know he was, and he left descendants who are alive today, which we also know is true, then he is the ancestor of everyone of European descent alive in Europe today.

Since most of this blog’s posts support academic disciplines looking for answers to the Indo-European question, and gives constantly reasons against modern genetic (and phylogenetic) identification, I think it is worth at least a quick read for anyone interested in the field.

I recently referred to the interesting series of posts by Graham Coop on this matter.

Featured image: Europe around 800 – the map is public domain from from the Historical Atlas (New York, 1911)

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