Stone tools and animal remains found on England's coast suggest that humans arrived in northern Europe at least 150,000 years earlier than was previously thought.

Maybe the toolmakers stayed. Maybe they were part of successive migrations that went north during Ice Age thaws, then retreated south when the cold came back.

Either way, "this has significant implications for our understanding of early human behavior, adaptation and survival, as well as the tempo and mode of colonization after their first dispersal out of Africa," wrote a team of researchers from the Ancient Human Occupation of Britain project in the July 7 Nature.

The researchers describe their excavation of a site in Happisburgh, a coastal town that sits on what was once an estuary of the River Thames.

Dozens of stone tools were found in sediments deposited when the polarity of Earth's magnetic field pointed south rather than north, a phase ending 780,000 years ago. No human bones were found, but animal fossils include the tooth of a mammoth species that disappeared 800,000 years ago, and bones of red deer that went extinct a million years ago. Pollen grains and plant fossils suggest a landscape in transition from temperate to Ice Age, which happened 950,000 years ago and again 840,000 years ago.

Until recently, it was thought that early humans stayed south after leaving Africa. The only human remains dating from around that time in Europe were found in Spain. But tentative evidence of sparse settlement in England, as well as in Germany and France, has raised the possibility of earlier northward expansion.

The latest findings reinforce that possiblity, move the dates back, and underscore just how resilient and resourceful early humans were.

"What I find amazing is that these early humans were pretty tough. They survived winters that were probably 5 degrees Fahrenheit colder than present," said Australian National University anthropologist Andrew Roberts, who wrote a commentary accompanying the findings. "I'd want a heated house – not a hunter-gatherer lifestyle. This tells us that these early humans were better adapted to cold than we thought."

It's not known from the tools and fossils whether the cold-hardy settlers had clothing, shelters or even fire. It's also not clear whether the remains represent a population that had migrated during a warmer time, or braved the cold in moving north.

Given those caveats, "I think the paper gives a sound provisional idea to test. The idea of investigating the limits of early human adaptability is now a vital dimension of paleoanthropological research," said Rick Potts, curator of anthropology at the Smithsonian's National Museum of Natural History.

"Knowing where we came from and how we fit in to the wider picture is fundamental to our existence," said Roberts. "If it was me, I would have stayed in the Mediterranean."

Images: 1) Artist's rendition of Happisburgh, about 900,000 years ago./John Sibbick, AHOB. 2) Stone hammer flakes, along with a fossilized pine cone (i) and mammoth tooth (j).

See Also:

Citation: "Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe." By Simon A. Parfitt, Nick M. Ashton, Simon G. Lewis, Richard L. Abel, G. Russell Coope, Mike H. Field, Rowena Gale, Peter G. Hoare, Nigel R. Larkin, Mark D. Lewis, Vassil Karloukovski, Barbara A. Maher, Sylvia M. Peglar, Richard C. Preece, John E. Whittaker & Chris B. Stringer. Nature, Vol. 466, No. 7303, July 8, 2010.

"Early human northerners." By Andrew P. Roberts and Rainer Grün. Nature*, Vol. 466, No. 7303, July 8, 2010.*

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.