Dozens of flint tools unearthed on the Norfolk coast have revealed that early humans who first evolved in Africa braved bitter conditions to settle in Britain.
The find at Happisburgh, around 20 miles from Norwich, marks the earliest known human settlement in northern Europe.
The Happisburgh humans, who researchers believe were from the now-extinct Homo antecessor species, are thought to have hunted for food in rich estuaries of the ancient River Thames, which then flowed into the North Sea in what is now Norfolk.
After travelling across the land bridge which linked Britain to the rest of Europe, the humans are believed to have settled on the edges of the boreal forests that covered much of the country.
Fossil remains found near the 78 flint artefacts – including many sharpened "flakes" – indicate that the humans shared the land with an array of exotic mammals, including rhinos, hyaenas, and mammoths.
Sabre-tooth cats would have been among their most feared predators.
While they have yet to unearth human fossils, researchers from the Natural History Museum, British Museum and the University of London are convinced that their five year dig into sand on the shore of Happisburgh has provided convincing evidence that humans lived on the site in the Early Pleistocene era.
Tests on the sediments in which the artefacts were buried found that they were laid down during a period when the planet's magnetic field was reversed. The last time the poles switched in this way was 780,000 years ago.
Analysis of fossils found at the site – including a long-extinct mammoth species – and climate records indicate that the humans must have been present between 850,000 and 950,000 years ago.
Professor Chris Stringer from the Natural History Museum said that the discovery was remarkable because it showed that ancient humans were better adapted to surviving colder conditions than previously thought.
Winters would have been around 3C colder than Britain today – roughly equivalent to modern conditions in southern Scandinavia – meaning that the humans were almost certainly advanced enough to wear rudimentary clothing, build shelter and make fire, according to the researchers.
“These finds are by far the earliest known evidence of humans in Britain," Prof Stringer said. "They have significant implications for our understanding of early human behaviour, adaptations and survival."
Evidence uncovered at a dig site in Pakefield, Suffolk in 2005 indicated that humans had managed to reach Britain about 700,000 years ago. Before then, it was thought that these shores were still unoccupied 500,000 years ago.
The latest find suggests that Britain has been subject to at least nine distinct human colonisations in history.
Simon Parfitt of University College London, who was also involved in the research, said: "The picture we are getting here is of humans coming into Britain regularly and then dying out, and the land having to be repopulated again by another group of people. It was too cold for them to survive in the long term."
Prof Stringer said that finding a human bone would be the "holy grail" of the excavation, which is part of the Ancient Human Occupation of Britain project. A report is published in this week's edition of Nature, the science journal.
Homo antecessor is the most likely candidate for "Happisburgh Man", as they were the only human species known to live in Europe at this time. Little is known about their physiology or habits, but fossil remains discovered in Spain indicate they had lower foreheads, stronger brows and bigger teeth than modern humans.
There are also suggestions from the Spanish excavations that they resorted to cannibalism. Prof Stringer said: "The Homo antecessor died out shortly afterwards. It was a dead end in human evolution."
Homo sapiens emerged from a separate branch of the evolutionary tree. Our ancestors are thought to have parted company with Neanderthals around 500,000 years ago.