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Ancient DNA reveals history’s most murderous people.

Starting 5000 years ago, the Yamnaya embarked on a violent conquest of Europe. Now genetic analysis tells their tale for the first time.

Humans

Stonehenge artwork

By Colin Barras

THE iconic sarsen stones at Stonehenge were erected some 4500 years ago. Although the monument’s original purpose is still disputed, we now know that within a few centuries it became a memorial to a vanished people. By then, almost every Briton, from the south coast of England to the north-east tip of Scotland, had been wiped out by incomers. It isn’t clear exactly why they disappeared so rapidly. But a picture of the people who replaced them is emerging.

The migrants’ ultimate source was a group of livestock herders called the Yamnaya who occupied the Eurasian steppe north of the Black Sea and the Caucasus mountains. Britain wasn’t their only destination. Between 5000 and 4000 years ago, the Yamnaya and their descendants colonised swathes of Europe, leaving a genetic legacy that persists to this day. Their arrival coincided with profound social and cultural changes. Burial practices shifted dramatically, a warrior class appeared, and there seems to have been a sharp upsurge in lethal violence. “I’ve become increasingly convinced there must have been a kind of genocide,” says Kristian Kristiansen at the University of Gothenburg, Sweden. As he and others piece together the story, one question resounds: were the Yamnaya the most murderous people in history?

Before about 5000 years ago, Neolithic Europe was inhabited by people much like those who raised Stonehenge. They were farmers with an urge to work together and build large stone structures. “It looks like these people were quite communal,” says Kristiansen. And that community spirit continued into the afterlife: many of their megalithic monuments served as shared graves – some containing the remains of up to 200 people.

They were also innovators. Patterns of wear on ancient cattle bones suggest they had worked out how to use livestock to pull heavy loads. They probably had wheeled vehicles and there may even have been proto-roads connecting communities. It looks like they were coming together to live in what Kristiansen calls “mega-settlements” with populations of up to 15,000 people.

In other words, Neolithic Europe appears to have been prosperous, community-minded and relatively peaceful. Then everything changed.

Starting about 5000 years ago in south-east Europe – a region bounded today by Ukraine in the east and Hungary in the west – a new style of burial custom appeared. The dead were interred alone in what archaeologists call “pit graves” rather than in communal structures. The body was decorated with a red pigment called ochre, and the grave chamber covered with wooden beams and marked by a mound of earth a few metres tall, dubbed a kurgan. This distinctive burial custom originated on the Eurasian steppe where it was associated in particular with the Yamnaya. According to archaeologist Volker Heyd at the University of Helsinki, Finland, its appearance in Europe indicates a traumatic shift that disrupted existing social patterns.

pots
Ancient DNA analysis reveals that Corded Ware people, who made these pots, were Yamnaya in origin

The disruption soon spread. In subsequent decades, Yamnaya-like artefacts and behaviour started popping up elsewhere on the continent. By 4900 years ago, the Corded Ware people – named after their distinctive pottery and adopting many Yamnaya customs – began to appear in central and northern Europe. The big question is: how and why did Yamnaya practices spread so far and so fast?

Until about five years ago, most archaeologists were convinced that this largely reflected the movement of ideas and technology while people stayed put – in much the same way that Nokia mobile phones swept across Europe in the late 1990s and early 2000s. But, in 2015, geneticists suggested an alternative. Teams led by David Reich at Harvard Medical School and Eske Willerslev at the University of Copenhagen in Denmark announced, independently, that occupants of Corded Ware graves in Germany could trace about three-quarters of their genetic ancestry to the Yamnaya. It seemed that Corded Ware people weren’t simply copying the Yamnaya; to a large degree they actually were Yamnayan in origin.

How the Yamnaya spread

Disease, warfare and death

Many archaeologists found the idea implausible. It is one thing to accept that the Yamnaya migrated from the Eurasian steppe to the steppe-like environments of south-east Europe, says Heyd, but quite another to argue for onward migrations into the heavily forested central and northern Europe. This implies that they spread into an environment they didn’t have experience exploiting, that they somehow displaced large numbers of people who were adapted to that environment – and that they did all of this in a just a few generations. To this day, Heyd struggles to understand how and why such rapid migrations could have occurred. Kristiansen, however, believes it is now possible to reconstruct a likely scenario. His model involves disease, warfare and death.

The first thing to appreciate, says Kristiansen, is that Neolithic Europe was in crisis just before the Yamnaya’s arrival. Using the pollen record from archaeological sites as a proxy for levels of agricultural activity, archaeologists have concluded that populations in northern and central Europe began shrinking about 5300 years ago. In December 2018, Kristiansen and his geneticist colleagues suggested an explanation. Examining the teeth of Neolithic people who lived in what is now Sweden about 5000 years ago, they found plague-causing bacteria – the earliest known relative of the Black Death. Further analysis suggested the disease began spreading across Europe perhaps as early as 5700 years ago.

Kristiansen thinks it is no coincidence that this is also when the settlements of south-east Europe reached their greatest size. Within those settlements, thousands of people lived in unhygienic conditions and in close contact with livestock, providing a perfect environment for plague to emerge. From there, the disease could have spread rapidly into central and northern Europe via the wheeled vehicles and proto-roads appearing at this time. “These mega-settlements were beginning to be abandoned and burned down a little after 5700 years ago,” says Kristiansen, which would make sense if they were becoming centres of death and disease. “By 5400 years ago, they were gone.”

This means that when the Yamnaya arrived a few centuries later, they were entering a Europe with a small and weakened indigenous population that could offer little resistance. Even so, says Kristiansen, this on its own cannot explain why the Yamnaya spread so rapidly, morphing to become the Corded Ware people. He thinks the sheer speed of this change hints that the Yamnaya migrants were dynamic and aggressive. This might suggest they were mainly young male warriors, riding into new territory. Most Yamnaya women don’t seem to have joined the migration until later.

skulls
Individual graves containing a body decorated with ochre are a hallmark of Yamnayan culture

In line with this idea, a controversial 2017 genetics study concluded that the DNA signal left in ancient European bones from the time is easiest to explain if there were between five and 14 male migrants for every female migrant. Archaeological evidence also points to most immigrants being men. For instance, a 2017 analysis of Corded Ware burials across a vast region from north-west Denmark to south-east Czech Republic concluded that male graves were very similar in style to one another – but female graves showed local variation. That would fit with the idea of male migrants with a shared sense of identity having children with Neolithic women who still retained some local traditions.

“The sheer speed of change hints that the Yamnaya were aggressive”

If the Yamnaya migrants did behave as Kristiansen suggests, Neolithic Europe’s men are likely to have objected, setting the stage for violent encounters. Some evidence that this was the case comes from a remarkable Corded Ware site called Eulau in Germany. Here, a handful of unusual graves each contain between two and four bodies – mostly women and their children. Analysis of isotopes in the women’s teeth reveals that they did not grow up locally. And injuries on five of the 13 bodies indicate that they met a violent end. Kristiansen interprets this as evidence of a brutal raid by Neolithic men taking revenge on migrants who had stolen “their” women. The absence of male burials suggests they waited until the village’s men were out tending their cattle before making the attack.

This sort of mass killing wasn’t unheard of in Neolithic Europe, says Christian Meyer at the OsteoArchaeological Research Centre, Germany, who was involved in the Eulau analysis. Nevertheless, it hints at an upsurge in violence about 5000 years ago. And there are other signs. “We do see a rather high number of trepanations [holes drilled in skulls],” he says – people may have undergone this procedure as a therapeutic measure after bad head injuries.

Axe-wielding warriors

However, if Eulau is an example of the violence that accompanied an influx of Yamnaya and their descendants, it is arguably not particularly representative. Kristiansen suspects it was the migrants who usually came out on top, judging by the fact that Corded Ware groups quickly multiplied and spread.

There may have been good reasons for this. Some archaeologists argue that the Yamnaya were accomplished horse riders. Even before they left the Eurasian steppe, some had become axe-wielding warriors – as depicted on ancient standing stones in the steppe landscape. They were also probably in better shape to fight too. Ancient DNA suggests they were unusually tall for the time. And they had a highly nutritious diet. “It looks like they lived mostly on meat and milk products,” says Kristiansen. “They were healthier and probably physically quite strong.”

burning village artwork

This scenario of young warriors moving through the landscape makes sense to Heyd. However, he cautions that it is based on evidence snatched from a few isolated sites. It is still far from clear, he says, that such a simple model can explain the spread of the Yamnaya and the rise of the Corded Ware people in its entirety.

Indeed, many archaeologists think the wider narrative emerging from genetic studies oversimplifies things. The trouble, according to Martin Furholt at the University of Oslo, Norway, is that geneticists divide prehistoric Europe into a series of large cultural blocks – Yamnaya in the south-east, Corded Ware in the north and so on – each of which represents a population with a shared sense of self.

“The idea that archaeological units of classification represent human groups of a shared social, or ethnic identity has been proven wrong many times during the history of research,” says Furholt. Ethnicity is founded on shared ancestry, whereas identity is more about culture. “Geneticists are basically looking at ethnicity. But archaeologists are foremost looking at identity,” says Heyd.

Watch: David Reich’s talk from New Scientist Live “The truth about us, and where we come from”

A striking example of this distinction is a discovery made near the town of Valencina de la Concepción in southern Spain. Archaeologists working there found a Yamnaya-like kurgan, below which was the body of a man buried with a dagger and Yamnaya-like sandals, and decorated with red pigment just as Yamnaya dead were. But the burial is 4875 years old and genetic information suggests Yamnaya-related people didn’t reach that far west until perhaps 4500 years ago. “Genetically, I’m pretty sure this burial has nothing to do with the Yamnaya or the Corded Ware,” says Heyd. “But culturally – identity-wise – there is an aspect that can be clearly linked with them.” It would appear that the ideology, lifestyle and death rituals of the Yamnaya could sometimes run far ahead of the migrants.

Geneticists are now beginning to realise just how complex things were, says Heyd. This was highlighted in a study published last year – the one that suggested the ancient Britons who built Stonehenge disappeared, as few of their genes survive to the present day – which brought together an enormous group of geneticists and archaeologists including Reich, Willerslev, Kristiansen and Heyd. There has been talk in the popular press recently about geneticists marginalising their archaeological collaborators in such studies. This wasn’t Heyd’s experience. “David [Reich] listened. He is listening,” he says.

The collaboration was an attempt to shed light on another group, the enigmatic Bell Beaker people, who emerged in Europe slightly later than the Corded Ware people. In some ways, they were similar to the Yamnaya: they buried their dead in single graves, had recognisable warriors and celebrated these warriors by occasionally carving their images on standing stones. As a result, the geneticists suspected that Bell Beaker people descended from the Yamnaya. However, the archaeologists convinced them this was only partially true.

The collaboration revealed that the origin and initial spread of Bell Beaker culture had little to do – at least genetically – with the expansion of the Yamnaya or Corded Ware people into central Europe. “It started in western Iberia,” says Heyd. It is in that region that the earliest Bell Beaker objects – including arrowheads, copper daggers and distinctive Bell-shaped pots – have been found, in archaeological sites carbon-dated to 4700 years ago. Then, Bell Beaker culture began to spread east, although the people more or less stayed put. By about 4600 years ago, it reached the most westerly Corded Ware people around where the Netherlands now lies. For reasons still unclear, the Corded Ware people fully embraced it. “They simply take on part of the Bell Beaker package and become Beaker people,” says Kristiansen.

Genetic wipeout

In other words, there were now two types of Bell Beaker people: one with roots in Iberia and one with Corded Ware (and ultimately Yamnaya) roots. Kristiansen thinks the Yamnaya Beakers then took advantage of the maritime know-how of their Iberian friends and voyaged to Britain some 4400 years ago (see Map). The fact that the genetic analysis showed the Britons then all-but disappeared within a couple of generations might be significant. It suggests the capacity for violence that emerged when the Yamnaya lived on the Eurasia steppe remained even as these people moved into Europe, switched identity from Yamnaya to Corded Ware, and then switched again from Corded Ware to Bell Beaker.

In fact, there is much stronger evidence that these Yamnaya Beakers were ruthless. By about 4500 years ago, they had pushed westwards into the Iberian Peninsula, where the Bell Beaker culture originated a few centuries earlier. Within a few generations, about 40 per cent of the DNA of people in the region could be traced back to the incoming Yamnaya Beakers, according to research by a large team including Reich that was published this month. More strikingly, the ancient DNA analysis reveals that essentially all the men have Y chromosomes characteristic of the Yamnaya, suggesting only Yamnaya men had children.

“The genetic analysis showed that the Britons who built Stonehenge all-but disappeared within a few generations of the Yamnaya’s arrival”

“The collision of these two populations was not a friendly one, not an equal one, but one where the males from outside were displacing local males and did so almost completely,” Reich told New Scientist Live in September.

This supports Kristiansen’s view of the Yamnaya and their descendants as an almost unimaginably violent people. Indeed, he is about to publish a paper in which he argues that they were responsible for the genocide of Neolithic Europe’s men. “It’s the only way to explain that no male Neolithic lines survived,” he says.

Surprisingly, this isn’t a new idea. Some prominent 20th century archaeologists were convinced that migrants from the steppe arrived in Europe about 5000 years ago. One of them, Marija Gimbutas, even argued that they were exceptionally aggressive individuals who brought violence and social change to the continent. Her ideas were deeply controversial in her lifetime. “But ironically, the geneticists are now coming quite close to what Gimbutas was writing about in the 1960s,” says Heyd.

What’s more, it is now emerging that the Yamnaya didn’t limit their sights to Europe. The latest genetic evidence reveals that they also went east into the Indian subcontinent (see “Europe is not enough“).

Even if they weren’t the most murderous people in history, there is no doubting that they spread far and wide. This may be another reason the Yamnaya story is gaining traction now. A few decades ago, mass migration was far from our minds, says Heyd, but the present social and political environment has changed that. Now we are acutely aware of the many forces that can spur huge groups of people to traverse the globe.

Europe is not enough

Almost all people of European descent can trace their paternal origins back to inhabitants of the Eurasian steppe. In recent years, it has become clear that these people, known as the Yamnaya, and their descendants travelled across the continent during the Neolithic replacing locals – particularly the men – as they went (see main story). Now we have discovered the Yamnaya also migrated east.

A study by David Reich at Harvard Medical School and his colleagues posted to the bioRxiv preprint server in 2018 gives us an idea of when and how this happened. Using DNA samples from the remains of hundreds of people who lived across south Asia between about 7000 and 3000 years ago, the team found evidence that Yamnaya-related DNA began appearing there between 4000 and 3000 years ago.

Those steppe pastoralists mingled with people who may have been related to the inhabitants of the famous Indus Valley Civilisation. In doing so, they formed an “Ancient North Indian” population, one of the two ancestral populations that define the ancestry of most people living in the Indian subcontinent today. What’s more, incomers from the steppe may have brought major cultural changes. Speaking at New Scientist Live in September, Reich pointed out that people in the Indian subcontinent today who carry the largest amounts of Ancient North Indian ancestry tend to speak similar languages to one another, and often (but not always) belong to upper castes.

As in Europe, it looks like the steppe migrants were largely young, male and violent. A study by Martin Richards at the University of Huddersfield, UK, and his colleagues found that maternally inherited mitochondrial DNA sequences changed relatively little when they arrived. By contrast, between 60 and 90 per cent of men now living in the area can trace their paternally inherited Y chromosome to Yamnaya-related migrants.

“Indigenous males seem to have been marginalised by the new arrivals much more than the women and were unable to have children to the same extent,” says Richards. “This seems unlikely to have been a wholly benign process.”

One Comment

  1. Alpheus Williams

    Fascinating read. Impressive research. Thank you.

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