3:06pm

Fri August 3, 2012
Science

A 20,000 Year Rewrite Of Human History

It turns out the Later Stone Age wasn’t quite so late. A University of Colorado archeologist has just completed a new analysis of artifacts that has pushed the period back by 20,000 years. The work may resolve one of the long-running paradoxes of human history—but in the process, it has created a new one.

45,000 years ago in Upper Paleolithic Europe, modern humans had arrived from Africa—possibly South Africa—and were busily crafting stone blades and bone tools, along with art objects and personal ornaments. But for the technological equivalent of this period in South Africa, known as the Later Stone Age, the earliest agreed upon evidence is just 22,000 years old.

Paola Villa, an archeologist with the University of Colorado Museum of Natural History in Boulder, was puzzled by the discrepancy.

“It was strange because we know that the Later Stone Age of South Africa was made by modern humans very much like the Upper Paleolithic,” says Villa.

...many technologies associated with the Later Stone Age were over 40,000 years old...

An expert in stone tools, Villa decided to take a closer look at artifacts from Border Cave, a site in South Africa near Swasiland. Along with her colleagues, she found many technologies associated with the Later Stone Age were over 40,000 years old—including the first known instance in South Africa of a digging stick tricked out with a stone to give it more weight.

Villa also found evidence of the use of a type of manufactured glue called pitch to attach small arrowheads to bone or wood, which involved heating tree bark in pits covered with stones.

“We’re realigning the Later Stone Age of South Africa with the dates of the Upper Paleolithic in Europe,” says Villa. “But at the same time, what is interesting is that there are such strong differences in technology and also the production of some of the bone tools and ornaments.”

For example, the stone tools in Europe are about the size of a finger, while in Africa they’re usually the size of a fingernail. So even though the chronology now fits, people who move usually bring along their own technology and culture.

Based on this archeological evidence, Villa says “it’s not possible to suggest that South Africa was the source of the modern human groups that went into the Near East and then Europe.”

A definitive answer will have to come from genetic analysis, if scientists are ever able to find enough preserved DNA to sequence.

But Villa is confident that the layers of artifacts at Border Cave do tell a clear story about the group living in South Africa: there was a gradual, internal evolution toward the more advanced tools that mark start of the Later Stone Age—and it all happened about 20,000 years earlier than originally thought.

Villa’s analysis was published on Monday in the Proceedings of the National Academy of Sciences (PNAS), along with a companion paper authored with collaborators who investigated the organic material.