New research indicates that two genetically separate populations of people migrated to the United Kingdom after the last ice age.
Scientists analyzed the remains of two humans who lived about 15,000 and 13,500 years ago, found in caves in England and Wales, respectively, writes Gizmodo’s Isaac Schultz. The results suggest the two individuals, who had different diets and cultures, also had distinct ancestries, reports Science’s Andrew Curry.
The findings, published last week in Nature Ecology & Evolution, come from the oldest human DNA found in the U.K., researchers say. It indicates that a migration, not simply a shift in customs, likely led to the change in culture after the last ice age.
“It’s clearly not the same group of modern humans everywhere,” Luc Amkreutz, an archaeologist at the National Museum of Antiquities in the Netherlands who did not contribute to the research, tells Science. “I think we’ve underestimated the diversity in this period.”
During the last ice age, glaciers were at their largest from roughly 29,000 to 19,000 years ago. Then, as the ice sheets started retreating, humans began moving back to England about 15,500 years ago, per the Guardian’s Nicola Davis.
These prehistoric humans, known as Magdalenians, spread to the north and west as they chased large mammals for food. They crossed over from continental Europe via a now-submerged land bridge called Doggerland.
One of the individuals examined in the study was uncovered in England from Gough’s Cave in the southwestern part of the country, per Science. Analysis of the genetic material revealed this person, who was female, shared ancestry with the Magdalenians, according to the Guardian.
Chemicals in the bones show that the Gough’s Cave individual largely subsisted on a diet of large mammals such as horses and reindeer, just as the Magdalenians did. Carved human bones and cups made from skulls found in the cave are consistent with the idea that Magdalenians might have eaten other humans.
In the following centuries, temperatures warmed, and the environment changed. The tundra disappeared as dense forests started to grow, writes Science.
As the climate shifted, so did the people. DNA analysis of the other remains, found in Kendrick’s Cave in Wales and dated to just 1,500 years later, suggest different ancestry. This person, a male, was related to a group called Western hunter-gatherers from southeast Europe or the near East, per the Guardian.
There are no signs of cannibalism or other alterations made to the bodies of the people buried in Kendrick’s Cave. And the diet of the individual found there likely consisted of fish and other marine life, according to Science.
“They have very different diets, and it does seem to line up with the genetics,” Rhiannon Stevens, a co-author of the new paper and an archaeologist at University College London in England, tells Science. “People seem to be moving with their habitats.”
“We can see that there are two different genetic ancestry present in Britain during this late glacial period, which is perhaps not what we expected to find,” Sophy Charlton, first author of the new study and an archaeologist at the University of York in England, tells the Guardian.
Stevens acknowledges to the Guardian that studying just two individuals doesn’t give the most comprehensive picture. Still, the findings match with what has been found elsewhere in Europe during that period—that Western hunter-gatherers mixed with or replaced Magdalenians, per Science.
“In keeping with what prehistorians have long known about the highly mobile, small populations of ice age hunter-gatherers, this [research] adds evidence to the growing picture of remarkably small, ecologically fragile human groups spread thinly across late Pleistocene Europe,” Paul Pettitt, an archaeologist at Durham University in England who did not contribute to the paper, tells the Guardian.
“Perhaps it’s not surprising to see the things happening are the same as in the rest of Europe,” Mateja Hajdinjak, a co-author of the paper and molecular biologist at the Francis Crick Institute in England, tells Science. “What’s surprising is how fast it happens.”