http://www.nature.com/news/2010/100707/full/news.2010.338.html

A harsh climate did not stop humans moving to northern Europe nearly a million years ago.

Miriam Frankel

Archaeological findings from the east coast of the United Kingdom reveal that early humans were living in northern Europe at least 80,000 years earlier than previously thought — some 780,000 years ago, and possibly as many as 950,000 years ago. These intrepid predecessors of modern Homo sapiens, expanding from southern Europe, may have had a surprising ability to adapt to colder climate conditions.

"These early humans endured a difficult climate surrounded by harsh coniferous woodlands," says Nicholas Ashton, an archaeologist from the British Museum in London and co-author of the study, which is published in Nature today1. "We really didn't think that early humans could cope with those kinds of environments."

The evidence comes from an excavation site at Happisburgh in East Anglia, which has been exposed by coastal erosion. It includes 78 knapped flint artefacts that the research team think were used by hunter-gatherers to pierce and cut meat or wood (see Nature's video).

The earliest humans moved to Europe from Africa around 1.8 million years ago. But because they were adapted to a warmer climate, archaeologists have so far believed that they didn't get as far north as Happisburgh — a comparatively cold, inhospitable place.

Other studies at archaeological sites in Germany2 and France3 have shown signs of human activity in the north around the same time, but the dating of these sites is perhaps not as well established as that at Happisburgh.

Looking for a date
The dating of the Happisburgh site is based on a combination of methods. The artefacts were entombed in sediment that records a reverse in the polarity of the Earth's magnetic field — the north and south poles switching places — at the time that they were laid down. The last polarity reversal is known to have been 780,000 years ago, making it probable that the Happisburgh artefacts are at least that old.

But smaller, fleeting polarity reversals also happen, which can complicate such palaeomagnetic dating. So the team backed up these results by looking at plant and animal fossils found in the sediment, such as the 'southern mammoth' (Mammuthus meridionalis).

The known overlap time between the disappearance of some species and the appearance of others narrows down the date bracket. The researchers' analysis, which also includes geological evidence from the ancient River Thames, indicates that the early humans occupied Happisburgh during the later part of a warm interglacial period, around 840,000 or 950,000 years ago.

The team used beetle and plant fossils from the site — which, unsurprisingly for a former floodplain, is extraordinarily rich in fossil species — to estimate the climate in Happisburgh at the time. The climate is thought to have been similar to that of southern Scandinavia today. "The beetle data do have some error margins, but the more data we get the more certain it becomes," says Ashton.

"The case is not absolutely watertight, but it is pretty good — the collective evidence strongly suggests that this is the oldest northern European site occupied by humans," says Andrew P. Roberts, a palaeomagnetist at the Australian National University in Canberra.

"The study also provides a really detailed environmental analysis that tells us a great deal about the environment and climate in which our human ancestors lived," he says.

Surprise find
Although evidence of human activity 700,000 years ago was found at nearby Pakefield4 in 2005, the Happisburgh findings came as a surprise to the researchers.

"We had accepted that there were people in the area 700,000 years ago, and we could explain it by the fact that it was really warm at that time," says Chris Stringer, a palaeoanthropologist from the Natural History Museum in London and a co-author of the study.

"The plants and animals in Britain at this point were the same as the ones in Spain — so they could have come up briefly under warm, peak temperatures, but were thought to have died out very quickly when it got cold," he says.

It is not known exactly how the early humans adapted to the cold climate — whether they made fires, built shelters or used clothing, says Stringer. And because there are no human remains at the site — they probably just visited it to hunt or scavenge — it is hard to make any predictions about the population size or organization of these people. "We don't know much about this early human, but we speculate that it could be the extinct species Homo antecessor — the 'Pioneer Man' — as it is the only species known in Europe at that time."

The research team will continue to investigate the Happisburgh site, hoping to one day find human fossils. They are also trying to find even older sediments to work out when the first humans really arrived there.

Ashton says, "We want to find out if they arrived during warmer peaks of the interglacial and just survived until the bitter end, or if they actually moved to northern Europe in a cold climate."