LONDON – Ancient man ventured into northern Europe far earlier than previously thought, settling on England's east coast more than 800,000 years ago, scientists said.

It had been assumed that humans — thought to have emerged from Africa around 1.75 million years ago — kept mostly to relatively warm tropical forests, steppes and Mediterranean areas as they spread across Eurasia.

But the discovery of a collection of flint tools some 135 miles (220 kilometers) northeast of London shows that quite early on man braved colder climes.

"What we found really undermines traditional views about how humans spread and reacted to climate change," said Simon Parfitt, a University College London researcher. "It just shows how little we know about the movement out of Africa."

About 75 flint tools have been found at the site near Happisburgh, a seaside hamlet in Norfolk, Parfitt and colleagues report in Thursday's issue of the journal Nature.

The researchers dated the artifacts to somewhere between 866,000 to 814,000 years ago or 970,000 to 936,000 years ago. That's at least 100,000 years before the earliest known date for British settlement, in nearby Pakefield.

Exactly what kind of humans made these tools is unknown.

"It is impossible to guess who those people were without fossil evidence," said Eric Delson, an anthropologist at Lehman College of the City University of New York, who was not involved in the research.

Mammoths and saber-toothed cats roamed the area at that time, and the River Thames flowed into the sea there — about 150 kilometers (90 miles) to the north of where its mouth is today. The climate was a little colder than now, at least during the winter.

The Natural History Museum's Chris Stringer, another of the paper's authors, said living in such an environment would have been challenging. Thick forests meant a poor supply of edible plants and dispersed prey. In the winter, there would be less daylight for hunting and foraging. Then, of course, there was the cold.

"For humans that have not long emerged from the tropic and the subtropics, that is something," Stringer said. "There's always been the view that that the cold was holding them back."

But the find suggests that it didn't. So how did these humans adapt? The researchers said the mix of a tidal river, marshes and coastline at the site might have helped, providing seaweed, tubers, and shellfish when prey was scarce.

"We could imagine these people exploiting the slow-flowing banks of the Thames, just as today," Stringer said.

Co-author Nick Ashton, with the British Museum in London, said there was still considerable uncertainty about how they adapted.

"Have they got effective clothing? Have they got effective shelters? Have they got controlled use of fire?" he said, adding that the find "provides more questions than answers."

Delson said that the discovery helped complete Europe's patchy prehistoric record.

"We don't know much, but we're increasing our knowledge of the earliest phases of what went on in Europe," he said. "It's one more piece of the puzzle."

Stringer, meanwhile, said he hoped more discoveries could be made along the coastline. He noted that he had already seen the chronology of human habitation in Britain pushed back, and then pushed back again.

"Now I'm thinking: 'Who knows, can we go back even further?'"