Hand axes were made 1.6 million years ago, twice as long ago as previously believed

January 3rd, 2009 - 2:31 pm ICT by ANI  

Washington, Jan 3 (ANI): New evidence has suggested that human ancestors in southern Africa were making hand axes as early as 1.6 million years ago, which is nearly twice as long ago as previously believed.

According to a report in Science News, these artifacts, which consisted of hand axes and two cleavers, were recovered from a diamond-mining pit in South Africa.

Estimates by archaeologist Ryan Gibbon and his colleagues, indicate that human ancestors in southern Africa fashioned these teardrop-shaped stone hand axes 1.6 million years ago, nearly twice as long ago as many researchers thought and about the time such tools are known to have first appeared in eastern Africa.

Gibbon and his colleagues dated hand axes and related stone implements, collectively known as Acheulean artifacts, using measures of the relative decay of radioactive forms of aluminium and beryllium in quartz grains from the soil and gravel bearing the artifacts.

Acheulean finds have been dated to 1.7 million years ago in Ethiopia. Less-advanced stone tools have been dated to as early as 2.5 million years ago in eastern Africa.

Over two days in 2005, Gibbons group identified 465 stone tools brought out of a diamond-mining pit bordering South Africas Vaal River, near the town of Windsorton.

Those implements included 10 hand axes, two hand axes with large chopping edges known as cleavers and two elongated, three-sided tools called picks.

The researchers have since recovered another 100 hand axes, 30 cleavers and 40 picks from the Windsorton pit.

Sand and gravel from five diamond-mining pits provided samples for dating, according to Gibbon.

Findings at Windsorton raise the question of whether human ancestors developed Acheulean tools independently in southern and eastern Africa at around the same time, developed the tools in only one area from which the tool-making tradition spread rapidly to distant regions.

Gibbon suspects that Homo ergaster, a species regarded as a direct ancestor of modern humans, made the Windsorton hand axes.

A nearby South African site has yielded H. ergaster fossils, but no fossils of any member of the human evolutionary family have been found in the Windsorton vicinity.

Fossil finds have linked H. ergaster to Acheulean tools in eastern Africa.

Gibbons teams findings support a preliminary age estimate of 1.6 million years that other researchers have reported for Acheulean artifacts from South Africas Wonderwerk Cave, located about 100 kilometers northwest of Windsorton.

Additional dating of Wonderwerk Cave deposits has confirmed that Acheulean activity there began 1.6 million years ago, with even older stone tools dating to 2 million years ago. (ANI)

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