Ancient stone-tool making method arose multiple times

More than 300,000 years ago, Stone Age people in Eurasia may have invented new technology on their own, instead of borrowing it from African migrants, as some researchers suspected.

A mix of stone artifacts sandwiched between lava flows in Armenia suggest that an early toolmaking method actually arose independently in multiple spots around the world, an international team of researchers reports in the Sept. 26 Science.

“This tells us that archaic humans were a lot more innovative than we give them credit for,” says archaeologist Mark White of Durham University in England.

For almost 20 years, he says, scientists have argued whether a way to make stone flakes, called Levallois technology, was invented in Africa and then spread to Eurasia as hominids traveled north.“It’s one of those hypotheses that gets stuck like glue to the scientific consciousness,” White says.

But the new find may loosen up the glue. The Armenian site holds evidence of both old tools — stone hand axes — and newer stone flakes, as well as signs of a transition from one toolmaking technology to the other. What’s more, the stone flakes from the Armenian site don’t really look like those found in Africa, says Harvard archaeologist Christian Tryon.

So the Eurasian hominids may have developed Levallois flake making themselves, rather than having African immigrants bring the technology in, says study coauthor Daniel Adler, an archaeologist at the University of Connecticut in Storrs.

Adler’s team didn’t uncover any bones at the site, so the researchers can’t say who these hominids were. And because the fossil record is sparse for this time period, categorizing hominids into different species is tricky.

But scientists do know that about 1.75 million years ago, African hominids invented a way to make stone tools with two faces such as hand axes by hammering chips off big lumps of rock. Archaeologists think hominids brought this toolmaking method to Eurasia some 600,000 to 900,000 years ago.

Hundreds of thousands of years later, Levallois flake-making technology emerged in Africa, some scientists believe. By carefully whittling stones into dome-shaped chunks, toolmakers could strike off sharp flakes that may have been useful for cutting and slicing. The innovation may have let hunter-gatherers lighten their loads, carrying stone flakes instead of heavy hand axes.

Some researchers “see these moments of innovation as rare events,” says archaeologist John Shea of Stony Brook University in New York. “One lone genius comes up with a new way of making stone tools and it spreads from one individual to the next.”

But the Armenian site suggests that multiple groups figured out how to create the flake tools.

Adler discovered the site in 2008, while walking along a river gorge. He spotted flood plain sediments under a lava flow and thought, “Wow, there’s got to be something there.” The flood plain would have made a good home for hominids, he says, and any artifacts would have been sealed beneath the lava.

There, Adler’s team found thousands of artifacts fashioned from obsidian, a glassy volcanic rock that can be whittled into tools with razor-sharp edges.

Obsidian is very sharp, Adler says. “You have to imagine that the people who made these tools had tough, swollen, leathery, gritty, dirty, bloody, scabby hands because they’ve spent their entire lives handling the rock.”

Close inspection of the artifacts and dating of volcanic ash mingled among the flood plain sediments suggested that the ancient Eurasians were making both hand axes and stone flakes around 330,000 years ago. That’s roughly the same time period from which archaeologists have found the earliest Levallois tools in Africa, Tryon says.

The new work suggests that Levallois didn’t come to Eurasia with traveling groups of African hominids. And it probably didn’t originate only in Africa, as some scientists suspected, White says. “We can’t keep on peddling this hypothesis anymore. We’ve got to accept that Levallois emerged in multiple places.”

Seeing the toolmaking method pop up in multiple places means that ancient hominids from this time period probably had the same basic technological capabilities, Tryon says. “The data from Armenia suggests that the tradition of being really innovative and figuring things out goes back hundreds of thousands of years.”