Earliest presence of humans in east Asia

The stone tools were carved from volcanic rock and chert. Image: Nature

By BBC News Online's Helen Briggs

Stone tools dated to 1.36 million years ago provide the earliest evidence yet of human occupation of northeast Asia.

The tools, which were found at an ancient settlement in northern China, show that early humans were able to adapt to extremes of temperature relatively early in their history.

The crude implements were likely to have been made by early humans known as Homo erectus, a predecessor to our own species, Homo sapiens.

According to many scientists, Homo erectus was the first early human to move out of Africa to populate Asia and Europe.

Behavioural adaptations

The tools were found as far as 40 degrees north - at Xiaochangliang in the Nihewan Basin, north China.

This comes as a surprise because the area was thought to be inhospitable to early humans of the time, which were used to warmer climes. It suggests that early humans emerged from the tropics with an inbuilt ability to adapt to their environment.

More than a million years prior to our own species, early humans showed a considerable degree of adaptability

Richard Potts, Smithsonian Institution

Although some of these changes may have been physiological - such as growing a thicker fat layer - the scientists, from China and the United States, believe behavioural adaptations were more important.

These ancient settlers may have survived by donning clothing, building shelters, or even making fire, although no direct evidence for such activities exists.

Richard Potts, director of the human origins programme at the Smithsonian Institution, Washington DC, US, said the habitat the people encountered would have varied dramatically over the course of hundreds of thousands of years.

Global spread

Wet, warm forests would have given way to cold, dry, silted open plains, he said.

"More than a million years prior to our own species, early humans showed a considerable degree of adaptability," Dr Potts told BBC News Online.

"The early humans were pretty much stuck on the north site of the Nihewan Basin where they couldn't move north or south to accommodate climate change, but had to adapt by being more versatile," he said.

"It could well be that these early humans were able to buffer with their bodies, physiologically, some aspects of the change between warm and cold," he added. "But we think in the main part, it must have been behavioural."

The research, reported in the scientific journal Nature, adds to the growing picture of early man's movement around the globe.

Archaeological evidence shows that less than half a million years after the Xiaochangliang camp was occupied, early humans were living about 600 kilometres further south, on the Yellow River.

It seems that Homo erectus was able to move over a considerable area, despite periods of drought.

Yet it remains a mystery exactly how these early people managed to survive.