Monday, 19 January 2009

Humans in Britain 700,000 Years Ago

Stone Tools Reveal Humans Lived in Britain 700,000 Years Ago

December 16, 2008

Stone tools found on the coast of Britain suggest early humans first colonized northern Europe much earlier than previously known. Ancient flints discovered in cliffs at Pakefield in eastern England show humans lived in northern Europe some 700,000 years ago, according to researchers. They say the find indicates that humans journeyed into Britain 200,000 years earlier than experts had suspected.

Flints typical of crafted tools used for butchering meat and cutting wood were found in sediments along with the remains of hippos, elephants, and other exotic animals. The long-extinct wildlife dates the flints back to a much warmer period when Britain was still connected to continental Europe via a land bridge. The discovery is described this week in the journal Nature.

"The early humans who made those tools were living in [England] in a Mediterranean-style climate, alongside creatures such as hippo, elephant, rhino, hyena, and lion," said study co-author Chris Stringer, an anthropologist at the Natural History Museum in London.

Ancient Clues

The stone tools were dated using various lines of evidence, including the bones of an extinct species of prehistoric water vole called Mimomys. Human artifacts have never before been found with the remains of this small mammal, the researchers say Ancient snails were also used to date the Stone Age cache through a method called amino acid geochronology.

The technique measures the extent of protein breakdown in animal matter to gauge how old it is. Previously the oldest evidence for human settlement in northern Europe came from fossilized teeth and bones found in England and Germany. Those remains are thought to belong to the species Homo heidelbergensis. Stringer says there has been much discussion about what social, technological, or bodily adaptations such humans would have needed in order to colonize northern Europe from the south.

But, he said, "the climate reconstructed for ancient Pakefield suggests that these pioneers migrated north in an environment that would have been familiar to them, during a short warm interval.” Researchers say telltale traces of frost-sensitive insects and plants no longer found in Britain imply that the settlers enjoyed warm summers and mild winters. The region would also have provided a resource-rich environment for Stone Age humans that supported many plants and animals, the study team reports. An additional attraction "was the flint-rich river gravels, which would have provided the raw material for tool manufacture," Stringer said.

Frozen Out

Severe, prolonged cold spells likely resulted in repeated interruptions to human occupation in northern Europe, Stringer says. "We do not yet know whether the people at Pakefield were part of a population that gave rise to later heidelbergensis, or whether new people, bearing hand-axe tools, came into western Europe and replaced or absorbed the previous inhabitants," he said.

The first flints were found in a coastal cliff in 2000, triggering intensive searching, which has so far uncovered 32 artifacts in all. The researchers say some of the flints remain razor sharp, despite the passage of 700,000 years, and that they all bear the hallmarks of human craftsmanship.

"The Pakefield evidence for human activity is rock-solid," according to Wil Roebroeks, professor of archaeology at Leiden University in The Netherlands. In an accompanying Nature article, Roebroeks wrote that the stone tools flout the widely held view, based on evidence found in Spain and Italy, that there was a long lapse between the occupation of the Mediterranean region and the settlement of northern Europe.

The new finds, he added, "will surely influence our understanding of the human occupation of Europe." "On a global scale, they are a reminder that we must be terribly careful with translating absence of evidence into evidence of absence."

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