About 2900 years ago, an elderly woman was carefully buried with two lambs in her lap and a piece of chalk in her hand at a site now called Cliff ’s End Farm, about 30 kilometers north of Dover, U.K. She had been killed by sword blows to her skull, likely in a sacrificial rite. Nearby lay the bodies of a teenager, two children, and a man whose bones had been bundled along with a copper-tipped cow bone. Two of the dead had been born in Europe, according to the isotopes in their teeth. Now, a study adds new insight into their origins: They may have been part of a wave of early Celtic speakers to reach Britain.
Researchers report in Nature today that the genomes of these people and nearly 800 others document a previously unknown great migration from Europe that transformed the genetic makeup of people in southern Britain in the Late Bronze Age, 3100 to 2700 years ago. The migrants likely introduced Celtic languages related to those spoken today in Ireland, Wales, and Scotland. It was “the last major prehistoric migration to Britain, and it probably came from France,” says archaeologist James Mallory of Queen’s University Belfast. If so, Celtic languages began to reach Britain as much as 1000 years earlier than expected, he says.
For decades, prehistorians thought Celtic languages arrived in Britain about 2400 years ago in the Iron Age, along with “Celtic” art and inscriptions first spotted in Central Europe. But debate raged over the timing, the source of the languages, and whether they spread through migration or diffused on their own. “Without genetics, every theory was debated,” Mallory says.
But now there are more ancient genomes from Britain than anywhere else. That is allowing researchers to trace the waves of people who reached the British Isles over the past 11,000 years. Hunter-gatherers came first, followed 6000 years ago by Early European Farmers (EEF) originally from Anatolia. About 4500 years ago, farmers with characteristic Bell Beaker pottery overran Britain, rapidly replacing 90% of inhabitants’ DNA and swamping out most of the EEF ancestry.
In the new study—the largest ancient DNA study to date—a team of more than 200 researchers, led by population geneticist David Reich of Harvard University and archaeologist Ian Armit of the University of York, explored how the genetic makeup of British people evolved from about 6000 to 2000 years ago. The team analyzed about 1 million alleles across the genomes of 793 people who lived in Britain and Europe.
The data revealed an influx of people with more EEF markers than local Britons, starting about 4400 years ago. They began to mix gradually. By the Late Bronze Age 2950 to 2875 years ago, the EEF ancestry in southern British people surged to 38%. Using a mathematical model, the team calculated that by the Iron Age, starting 2750 years ago, EEF were the source of about half of the DNA of people living in southern Britain. “We’re seeing people moving on a scale to sufficiently alter the genetic makeup of the populations in southern Britain,” Armit says.
The researchers found that the genomes of the migrants buried near Dover were closely related to those of people then living at sites in France and Spain, including skeletons tied to the Urnfield culture of Central Europe, thought to have links to early Celtic languages. But Reich says scientists need more DNA from Europe, especially France, to pinpoint the migrants’ homeland.
The results boost a theory that Celtic languages spread from France to Britain in the Late Bronze Age. “I’m delighted, but I’m obviously biased,” says philologist Patrick Sims-Williams at Aberystwyth University, who backs this idea. But some modern people who identify as “Celts” (a term archaeologists say includes diverse material cultures) and speak Celtic languages they consider indigenous, such as Irish, Scottish Gaelic, or Welsh, could find the results “unsettling,” Sims-Williams says. “Celtic becomes just one of a succession of languages that migrants have brought to Britain over the course of 2000 years or so: Latin with the Romans, English with the Anglo-Saxons, Norse with the Vikings, French with the Normans.”
The later migrations and political dominance of the English eventually marginalized Celtic languages, leaving them spoken chiefly beyond England’s borders, Armit says.
Others agree that the new study fits historical and archaeological evidence of close ties between Britain and Europe in the Late Bronze Age, when sailors used the white cliffs of Dover as a guide to cross the English Channel at its narrowest point and find the entrance to the Thames River. The new study shows “centuries of migration, with men, women, and children across all levels of society moving,” says University of York archaeologist Lindsey Büster—the kind of population shift that sustains language change. By the end of the Bronze Age, cultures on both sides of the channel had many similarities.
But tying a language to DNA is tricky, cautions geneticist Dan Bradley of Trinity College Dublin. He’s seeking traces of French blood in ancient Irish DNA, to find out whether the early Celtic speakers also made it to Ireland, today’s Celtic heartland.