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Home , Ancient DNA, Archaeogenetics, Gustaf Kossinna, Human genome, Long barrow

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THE BATTLE FOR COMMON GROUND Ancient are revolutionizing the study of but sometimes straining the relationships between archaeologists and .

BY EWEN CALLAWAY

hirty kilometres north of , echoed distant trends in continental Europe, through the rolling countryside of south- such as the appearance of bell-shaped beakers T west England, stands a less-famous — a connection that signals the arrival of new window into Britain. Established ideas and people in Britain. But many archaeol- around 3600 bc by early farming communi- ogists think these material shifts meshed into a ties, the is an earthen generally stable culture that continued to follow with five chambers, adorned with giant its traditions for centuries. stone slabs. At first, it served as a for some “The ways in which people are doing things three dozen men, women and children. But peo- are the same. They’re just using different mate- ple continued to visit for more than 1,000 years, rial culture — different pots,” says Neil Carlin at filling the chambers with relics such as University College Dublin, who studies Ireland The West Kennet long ROBERT HARVEY/NATURAL WORLD PHOTOGRAPHY WORLD ROBERT HARVEY/NATURAL and beads that have been interpreted as tributes and Britain’s transition from the Neolithic into to ancestors or gods. the Copper and Bronze Ages. barrow served as a The artefacts offer a view of those visitors But last year, reports started circulat- tomb and ceremonial and their relationship with the wider world. ing that seemed to challenge this picture of site for more than a Changes in pottery styles there sometimes stability. A study1 analysing -wide millennium.

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NEWS FEATURE data from 170 ancient Europeans, including assumptions about the spread of ideas from the bedfellows for more than 30 years — the first 100 associated with Bell Beaker-style artefacts, Near East. “Much of prehistory, as written in ancient-human DNA paper4, in 1985, reported suggested that the people who had built the the existing textbooks is inadequate: some of it, sequences from an Egyptian (now barrow and buried their dead there had all but quite simply wrong,” Renfrew surmised. thought to be contamination). But improve- vanished by 2000 bc. The genetic ancestry of It wasn’t an easy changeover — early carbon- ments in sequencing in the mid- Neolithic Britons, according to the study, was dating efforts were off by hundreds of years or to-late 2000s set the fields on a collision course. almost entirely displaced. Yet somehow the new more — but the technique eventually allowed In 2010, led by at arrivals carried on with many of the Britons’ tra- archaeologists to stop spending most of their the Natural History of Denmark used ditions. “That didn’t fit for me,” says Carlin, who time worrying about the age of and arte- DNA from a lock of from a 4,000-year-old has been struggling to reconcile his research facts and focus instead on what the remains native Greenlander to generate the first com- with the DNA findings. meant, argues Kristian Kristiansen, who studies plete sequence of an ancient-human genome3. The Bell Beaker ‘bombshell’ study appeared the at the University of Gothenburg Seeing the future of the field before his eyes, in Nature2 in February and included 230 more in Sweden. “Suddenly there was a lot of free Kristiansen asked Willerslev to team up on a samples, to make it the largest ancient-genome intellectual time to start thinking about pre- prestigious European Research Council grant study on record. But it is just the latest exam- historic societies and how they are organized.” that would allow them to examine human ple of the disruptive influence that has Ancient DNA now offers the same opportunity, mobility as the late Neolithic gave way to the had on the study of the human past. Since 2010, says Kristiansen, who has become one of his Bronze Age, some 4,000–5,000 years ago. when the first ancient- was fully field’s biggest cheerleaders for the technology. sequenced3, researchers have amassed data Genetics and have been uneasy ASSOCIATION PROBLEMS on more than 1,300 individuals (see ‘Ancient Migration has been a major source of tension genomes’), and used them to chart the emer- for archaeologists. They have debated at length gence of agriculture, the spread of languages whether human movements are responsible and the disappearance of pottery styles — “THESE for cultural changes in the archaeological topics that archaeologists have laboured over record, such as the Bell Beaker phenomenon, for decades. or whether it is simply the ideas that are mov- Some archaeologists are ecstatic over the RESULTS WERE ing through cultural exchanges. Populations possibilities offered by the new technology. identified by the artefacts they associated with Ancient-DNA work has breathed new life and came to be seen as a remnant of the ’s excitement into their work, and they are begin- A SHOCK TO THE colonial past, and one that imposed artificial ning once-inconceivable investigations, such categories. “Pots are pots, not people,” goes a as sequencing the genome of every individual common refrain. from a single graveyard. But others are cautious. ARCHAEOLOGICAL Most archaeologists have since cast aside “Half the archaeologists think ancient DNA the view that prehistory was like a game of can solve everything. The other half think Risk, in which homogenous cultural groups ancient DNA is the devil’s work,” quips Philipp COMMUNITY.” conquer their way across a map of the world. Stockhammer, a researcher at Ludwig-Maximil- Instead, researchers tend to focus on under- ians University in Munich, Germany, standing a small number of ancient who works closely with geneticists sites and the lives of the people who and molecular biologists at an insti- lived there. “Archaeology had moved tute in Germany that was set up a few away from these grand narratives,” years ago to build bridges between the says Tom Booth, a bioarchaeologist at disciplines. The technology is no silver the Natural History Museum in London, bullet, he says, but archaeologists ignore it who is part of a team using ancient DNA to at their peril. trace the arrival of farming in Britain. “A lot Some archaeologists, however, worry that of people thought you needed to understand the molecular approach has robbed the field change regionally to understand people’s lives.” of nuance. They are concerned by sweeping Ancient-DNA work — which has repeat- DNA studies that they say make unwar- edly shown that a region’s modern inhabitants

ranted, and even dangerous, assumptions are often distinct from populations that lived OXFORD/BRIDGEMAN ASHMOLEAN MUSEUM/UNIV. about links between and culture. there in the past — promised, for better or “They give the impression that they’ve worse, to bring back some of the broad focus sorted it out,” says Marc Vander Linden, on migration to human prehistory. “What an archaeologist at the University of genetics is particularly good at is detect- Cambridge, UK. “That’s a little bit irri- ing change in populations,” says David t at i n g .” Reich, a population at Harvard This isn’t the first time archaeologists Medical School in Boston, Massachusetts. have had to contend with transformative Archaeologists, Kristiansen says, “were technology. “The study of prehistory today prepared to accept that individuals had is in crisis,” wrote Cambridge archaeolo- travelled”. But for the Bronze Age period that gist Colin Renfrew in his 1973 book Before he studies, “they were not prepared for major Civilization, describing the impact of radio- migrations. That was a new thing.” carbon dating. Before the technique was devel- Studies of strontium isotopes in teeth5, which oped by chemists and physicists in the 1940s vary with local geochemistry, had hinted that and 50s, prehistorians determined the age of some Bronze Age individuals had moved sites using ‘relative chronologies’, in some cases Bell Beaker pots signal a period of unprecedented hundreds of kilometres over their lifetimes, relying on ancient Egyptian calendars and false cultural intermingling for early Europeans. Kristiansen says. He and Willerslev wondered

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whether DNA analysis might detect movements of whole populations during this period.

They would have competition. In 2012, 686 David Anthony, an archaeologist at Hartwick ANCIENT College in Oneonta, New York, loaded his car SOURCE: SOURCE:DAVID with boxes of human remains that he and his GENOMES colleagues had excavated from the steppes near More than 1,300 genome the Russian city of Samara, including bones sequences have been produced In the largest ancient-DNA study to associated with a Bronze Age pastoralist culture from the remains of ancient date, scientists sequenced the remains called the Yamnaya. He was bringing them to , sometimes challenging of 400 Neolithic, Copper-Age and the historical narratives derived Bronze-Age Europeans, including 226 the ancient-DNA lab just established by Reich from artefacts. associated with Bell Beaker artefacts. in Boston. Like Kristiansen, Anthony was com- fortable theorizing about the past on a grand scale. His 2007 book The , the and Europe Language proposed that the Eurasian steppe North had been a melting pot for the modern devel- America opments of horse and wheeled South A 4,500-year-old skeleton from a in America Ethiopia provided the rst ancient-human transport, which propelled the spread of a fam- genome sequence from Africa, providing ily of languages called Indo-European across Oceania context on movements back from Eurasia. Europe and parts of Asia. Africa Scientists expect many more examples 6,7 from Africa this year. In duelling 2015 Nature papers , the teams Asia 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

— had replaced much of the pool Total: 287

of central and Western Europe around 4,500– 239 5,000 years ago. This was coincident with the disappearance of Neolithic pottery, burial styles and other cultural expressions and the emer- 2010 gence of Corded Ware cultural artefacts, which are distributed throughout northern and cen- 2011

tral Europe. “These results were a shock to the 114

archaeological community,” Kristiansen says. 30 CORD CUTTERS 2012 The conclusions immediately met with push-back. Some of it began even before the papers were published, says Reich. When he 2013 2014 2015 2016 2017 2018 (until March) circulated a draft among his dozens of collabo- rators, several archaeologists quit the project. To many, the idea that people linked to Corded west that predate Yamnaya culture, he says. that such “molecular chauvinism” prevents Ware had replaced Neolithic groups in Western None of these facts negates the conclusions of meaningful engagement9. “It’s as though genetic Europe was eerily reminiscent of the ideas of the genetics papers, but they underscore the data, because they’re generated by people in lab , the early-twentieth-century insufficiency of the articles in addressing the coats, have some sort of unalloyed truth about German archaeologist who had connected questions that archaeologists are interested in, the Universe.” to the people of modern he argued. “While I have no doubt they are basi- Horsburgh, who is seeing her own field of Germany and promoted a ‘Risk board’ view of cally right, it is the complexity of the past that is African prehistory start to feel the tremors prehistory known as settlement archaeology. not reflected,” Heyd wrote, before issuing a call of ancient , says that archaeologists The idea later fed into Nazi ideology. to arms. “Instead of letting geneticists determine frustrated at having their work misinterpreted Reich won his co-authors back by explicitly the agenda and set the message, we should teach should wield their power over archaeological rejecting Kossinna’s ideas in an essay included in them about complexity in past human actions.” remains to demand more equitable partnerships the paper’s 141-page supplementary material7. Ann Horsburgh, a molecular anthropolo- with geneticists. “Collaboration doesn’t mean I He says the episode was eye-opening in showing gist and prehistorian at Southern Methodist send you an e-mail saying ‘hey, you’ve got some how a wider audience would perceive genetic University in Dallas, Texas, attributes such ten- really cool bones. I’ll get you a Nature paper.’ studies claiming -scale ancient migrations. sions to communication problems. Archaeol- That’s not a collaboration,” she says. Still, not everyone was satisfied. In an essay8 ogy and genetics say distinct things about the Many archaeologists are also trying to titled ‘Kossinna’s Smile’, archaeologist Volker past, but often use similar terms, such as the understand and engage with the inconvenient Heyd at the University of , UK, disagreed, name of a material culture. “It’s C. P. Snow all findings from genetics. Carlin, for instance, says not with the conclusion that people moved west over again,” she says, referring to the influential that the Bell Beaker genome study sent him on from the steppe, but with how their genetic ‘Two Cultures’ lectures by the British “a journey of reflection” in which he questioned signatures were conflated with complex cul- lamenting the deep intellectual divide between his own views about the past. He has pored over tural expressions. Corded Ware and Yamnaya the sciences and the humanities. Horsburgh the selection of DNA samples included in the burials are more different than they are similar, complains that genetic results are too often study as as the basis for its conclusion that and there is evidence of cultural exchange, at given precedence over inferences about the the appearance of Bell Beaker artefacts coin- least, between the Russian steppe and regions past from archaeology and , and cided with a greater than 90% replacement in

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Britain’s gene pool. “I didn’t want to be question- institute, his team identified DNA from plague- local family tree, while also determining how ing it from a position of ignorance,” Carlin says. causing in the teeth of people who died individuals fit into larger ancestry patterns. This Like Heyd, he accepts that a shift in ancestry from the Black Death in the fourteenth century, should allow researchers to ask how biological occurred (although he has questions about its the first direct evidence of a potential cause for kinship relates to the inheritance of material timing and scale). Those results, in fact, now the pandemic12. At Jena, Krause hoped to bring culture or status. “These are the big questions have him wondering about how cultural prac- genetics to bear, not just on ‘prehistorical’ peri- of history. They can be solved now only with tices such as leaving pottery and other tributes ods such as the Neolithic and the Bronze Age, collaboration,” says Stockhammer. at the West Kennet long barrow persisted in the where archaeological methods are the main Another glimpse of this approach appeared in face of such upheavals. “I would characterize a for reconstructing the past, but also on more- February on the bioRxiv preprint server14. The lot of these papers as ‘map and describe’. They’re recent times. Outreach with historians is still a paper explores Europe’s migration period, when looking at the movement of genetic signatures, work in progress, but archaeology and genet- ‘barbarian hordes’ filled the void left after the fall but in terms of how or why that’s happening, ics are thoroughly embedded at the institute. of the . In the paper, a team of those things aren’t being explored,” says Carlin, The department Krause directs is even called geneticists, archaeologists and historians built who is no longer disturbed by the disconnect. “I . “We have to be interdiscipli- family trees of 63 individuals from two medieval am increasingly reconciling myself to the view nary,” he says, because geneticists are addressing cemeteries in Hungary and northern Italy asso- that archaeology and ancient DNA are telling ciated with a group known as the Longobards. different stories.” The changes in cultural and They found evidence of high-status outsiders social practices that he studies might coincide buried in the cemetery: most bore central and with the population shifts that Reich and his “ARCHAEOLOGISTS northern European genetic ancestry that dif- team are uncovering, but they don’t necessarily fered from that of local people, who tended to have to. And such biological insights will never be buried without goods — offering tentative fully explain the human experiences captured WILL EMBRACE support to the idea that some barbarian groups in the archaeological record. included outsiders. Reich agrees that his field is in a “map-- Patrick Geary, a medieval historian at the ing phase”, and that genetics is only sketching THIS TECHNOLOGY Institute for Advanced Study in Princeton, out the rough contours of the past. Sweeping New Jersey, who co-led the Longobard study, conclusions, such as those put forth in the would not comment on the research because 2015 steppe migration papers, will give way to AND WILL NOT BE it is now being peer reviewed. But he says that regionally focused studies with more subtlety. genetic studies of historical times, such as the This is already starting to happen. Although migration period, carry pitfalls, too. Histori- the Bell Beaker study found a profound shift LUDDITES.” ans are increasingly incorporating data such in the genetic make-up of Britain, it rejected as palaeoclimate records into their work, and the notion that the cultural phenomenon was questions and time periods that archaeologists, will do likewise with ancient DNA, Geary says. associated with a single population. In Iberia, linguists and historians have been poring over But they share archaeologists’ fears that biology individuals buried with Bell Beaker goods were for decades. and culture will be conflated, and that problem- closely related to earlier local populations and Krause and his team have been heavily atic designations such as Franks or Goths or shared little ancestry with Beaker-associated involved in the map-making phase of ancient Vikings will be reified by genetic profiles, over- individuals from (who were genomics (he worked closely with Reich’s team riding insights into how ancient peoples viewed related to steppe groups such as the Yamnaya). on many such projects). But a study published themselves. “These days, what historians want The pots did the moving, not the people. late last year13 that focused on the transition to know about is identity,” he says. “Genetics Reich describes his role as that of a ‘mid- between the Neolithic and Bronze Age in cannot answer these questions.” wife’ delivering ancient-DNA technology to Germany won plaudits from archaeologists who Reich concedes that his field hasn’t always archaeologists, who can apply it as they see have been dubious of the larger-scale ancient- handled the past with the nuance or accuracy fit. “Archaeologists will embrace this technol- DNA studies. that archaeologists and historians would like. ogy and will not be Luddites,” he predicts, “and Led by Stockhammer, who also has a post at But he hopes they will eventually be swayed by they’ll make it their own.” the Jena institute, the team analysed 84 Neo- the insights his field can bring. “We’re barbar- lithic and Bronze Age skeletons from southern ians coming late to the study of the human past,” A STRONGER PARTNERSHIP Bavaria’s Lech River Valley dating to between Reich says. “But it’s dangerous to ignore barbar- Nestled in a sleepy valley in the state of 2500 and 1700 bc. The diversity in the genomes ians.” ■ SEE EDITORIAL P.559 Thuringia in former East Germany, the city of of cellular structures known as mitochondria, Jena has become an unlikely hub for the con- which are inherited maternally, rose during this Ewen Callaway writes for Nature from vergence of archaeology and genetics. In 2014, period, suggesting an influx of women. Mean- London. the prestigious Max Planck Society established while, strontium isotope levels in teeth — which 1. Olalde, I. et al. Preprint at bioRxiv http://dx.doi. an Institute for the Science of are set during childhood — suggested that most org/10.1101/135962 (2017). 2. Olalde, I. et al. Nature 555, 190–196 (2018). there and installed a rising in ancient- females weren’t local. In one case, two related 3. Rasmussen, M. et al. Nature 463, 757–762 (2010). DNA research, , as a director. individuals who lived within a few generations 4. Pääbo, S. Nature 314, 644–645 (1985). Krause was a protégé of the geneticist Svante of each other were found buried with different 5. Frei, K. M. et al. Sci. Rep. 5, 10431 (2015). 6. Allentoft, M. E. et al. Nature 522, 167–172 (2015). Pääbo, at the Max Planck Institute for Evo- material cultures. In other words, some cultural 7. Haak, W. et al. Nature 522, 207–211 (2015). lutionary Anthropology in Leipzig. There, shifts in the archaeological record could be due 8. Heyd, V. Antiquity 91, 348–359 (2017). Krause worked on the genome10 not to massive migrations, but to the systematic 9. Horsburgh, K. A. J. Archaeol. Sci. 56, 141–145 and helped discover a new archaic human mobility of individual women. (2015). 11 10. Green, R. E. et al. Science 328, 710–722 (2010). group, known as . It is the prospect of more such studies that 11. Krause, J. et al. Nature 464, 894–897 (2010). Whereas Pääbo was focused on applying has archaeologists salivating over ancient DNA. 12. Bos, K. I. et al. Nature 478, 506–510 (2011). 13. Knipper, C. et al. Proc. Natl Acad. Sci. USA 114, genetics to biological questions about ancient In the near future, says Stockhammer, archae- 10083–10088 (2017). humans and their relatives, Krause saw a wider ologists will be able to sequence the genomes 14. Amorim, C. E. G. et al. Preprint at bioRxiv http:// scope for the technology. Before leading the Jena of all the individuals at a burial site and build a dx.doi.org/10.1101/268250 (2018).

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