Europe gains an edge in ax mystery

— -- Archaeologists have long been puzzled by a 1-million-year pause between when early humans started making sophisticated hand axes with two-faced blades in Africa 1.5 million years ago and when the technology finally got to Europe.

But new research is showing that advanced Stone Age tools got to Europe close to the time they reached other sites outside of Africa.

In a letter published today in Nature, two archaeologists have shown that axes from southeastern Spain are from 900,000 years ago, much older than had been believed.

That would mean it took about 600,000 years for the new ax-making technique to get to Europe.

What was surprising was that older axes hadn't been found before in Europe, says archaeologist Luis Gibert, a co-author on the letter.

The work is credible, says Rick Potts, director of the Human Origins Program at the Smithsonian Institution's National Museum of Natural History in Washington, D.C.

"If you asked me yesterday when were the earliest hand axes in Europe, I would say we have an excellent site in England called Boxgrove and that's about 500,000," he says. The new research has almost doubled that time period, from 500,000 to 900,000 years ago, Potts says.

Gibert and fellow author Gary Scott are at the Berkeley Geochronology Center, a research institute in Berkeley, Calif., that studies the history of the Earth and dating methods. They used analysis of changes in the Earth's magnetic fields to date the axes.

This dating technique works because the Earth?s magnetic polarity has flipped back and forth over the course of history. "So north would be south and south would be north," says Potts. "The last one that occurred was 780,000 years ago, and that's when north became north."

Very fine-grained magnetic materials in the rock will orient themselves with the current magnetic field, making it possible to measure which era a given area came from by dating the polarity of the Earth?s magnetic fields at the time.

Stone axes, called Acheulian by archaeologists, were "the Swiss Army Knife of the Stone Age," Potts says.

"If you wrapped a piece of hide around your hand, you could use them hack through the joint of an elephant. You could use the flakes that come off them to whittle sticks to dig for grubs, you really could use them to do a lot of things. They were really handy things to carry around with you," he says

The first documented appearance of such hand axes was in Ethiopia about 1.5 million years ago, Potts says. Evidence shows they made their appearance in India about 1.1 or 1.2 million years ago, followed by Europe about 900,000 years ago and China 800,000 years ago, he says.

They were used by early humans, called Homo erectus, until they began to be replaced by a smaller, more mobile kit of specialized stone tools about 400,000 years ago, Potts says.

Perhaps even more interesting than the previous gap in the arrival of the hand-ax technology is why the axes weren't more popular outside Africa, says Ian Tattersall, curator in anthropology at the American Museum of Natural History in New York.

Common at sites in Africa, the hand axes are much rarer in Europe and Asia. "That's the question: If this was such a revolutionarily wonderful new technology, why weren't they more widely used?" Tattersall says.

The hand axes require a much higher level of mental sophistication than the stone flakes previously used by early humans, Tattersall says.

Making the flakes just required "bashing one stone with another. You didn't care about the shape," he says. For the stone axes, "you had to have an idea of what the tool should look like in your mind before you started making it."