A massive sheet of ice covered two-thirds of the British Isles around 27,000 years ago, making the region unsuitable for human habitation.

That all changed as the climate warmed, transforming the landscape and inviting communities to settle on its fertile soils. Archeologists are piecing together the stories of those early migrants, discovering that the region became a cultural melting pot.

The oldest human genomes discovered in either Britain or Ireland point to at least two distinct origin stories, each leading back to the European mainland and beyond.

One fossilized individual from Somerset’s Gough’s Cave has a genome that can be linked to ancestors discovered in Spain and Belgium.

Another from Kendrick’s Cave in Wales has genetic ties to ancestors found in Italy.

Both humans were alive in Britain more than 13,500 years ago, just a few thousand years after the region’s massive sheet of ice retreated towards the Arctic, according to radiocarbon dating.

The bones from Gough’s Cave are the more ancient of the two. They died around 15,000 years ago, implying that their ancestors were probably part of a wave of migration from northwest Europe at least a thousand years before their time.

The individual from Kendrick’s Cave lived a few thousand years later, and their ancestors most likely migrated to Britain from the Near East around 14,000 years ago.

“Finding the two ancestries so close in time in Britain, only a millennium or so apart, adds to the emerging picture of Paleolithic Europe, which is one of a changing and dynamic population,” says evolutionary anthropologist Mateja Hajdinjak of the United Kingdom’s Francis Crick Institute.

The British-Irish ice sheet had nearly vanished by 16,000 years ago. Fossils from this period are scarce, and other human remains discovered date back only to about 15,500 years ago, a few centuries before Britain’s climate began to warm rapidly.

The identities of these individuals and their origins remain unknown.

Archaeologists revealed in 2018 that a human fossil discovered in Gough’s cave dated back about 10,500 years. This fossil, known as the ‘Cheddar Man,’ was the oldest human in England at the time to have their entire genome sequenced.

According to the findings, the ancient man had dark skin and blue eyes, indicating that the population had yet to adapt to higher, colder latitudes. The ancestors of the Cheddar Man were a mix of western European hunter-gatherers and members of an earlier migration to England.

Many of the same researchers who worked on previous studies are involved in this latest investigation, hoping to find more ancestral connections.

“We really wanted to find out more about who these early populations in Britain might have been,” says Selina Brace of the Natural History Museum in England, who worked on both papers.

“We knew from previous research, including the Cheddar Man study, that western hunter-gatherers were in Britain around 10,500 years ago, but we didn’t know when they first arrived or if this was the only population present.”

According to the new findings, post-glacial settlers in Britain were not only genetically distinct. They appear to be culturally distinct as well.

The burial practices and diets in Gough Cave and Kendrick’s Cave were noticeably different. The Gough Cave contains evidence of both animal and human bones. A human skull shaped like a cup was discovered, possibly for cannibalistic purposes.

Meanwhile, the human from Kendrick’s Cave has chemical traces of eating marine and freshwater fish and mammals in their bones. Unlike Gough’s Cave, however, there are no signs of human-eating deer, aurochs, or horses.

“When these lines of evidence are considered together, they support the interpretation that at least two distinct human groups, with distinct genetic affinities and dietary and cultural behaviors, were present in Britain during the Late Glacial,” the authors write.

One lineage is linked to ancestors discovered in Villabruna, Italy, while the other appears to be a mix of Goyet ancestry from Belgium and El MirĂ³n ancestry from Spain.

Some theories suggest that the Cheddar Man is a hybrid of all three ancestors.

“This paints a picture of a dynamic and varied Late Glacial period within Britain, with changes occurring in diet, funerary behaviors, technologies, and genetic affinity in the Late Upper Palaeolithic at a time of rapid environmental and ecological change,” the authors conclude.

“The emerging scenario is one of multiple genetic population turnover events in the United Kingdom, based on the addition of our data to the existing knowledge of early prehistoric genetics in Britain.”