A fresh look at stone age tools

You probably think of new technologies as electronics you can carry in a pocket or wear on a wrist. But some of the most profound technological innovations in human evolution have been made out of stone. For most of the time that humans have been on Earth, they’ve chipped stone into useful shapes to make tools for all kinds of work.

In a study just published in Nature, we’ve dated a distinctive and complex method for making stone tools to a much earlier timeframe in China than had previously been accepted. Archaeologists had thought that artifacts of this kind had been carried into China by groups migrating from Europe and Africa. But our new discovery, dated to between 170,000 and 80,000 years ago, suggests that they could have been invented locally without input from elsewhere, or come from much earlier cultural transmission or human migration.

Several different species of humans lived on Earth at this time, including modern ones like us. But we haven’t found any human bones from this site, so don’t know which species of human made these tools.

These Chinese artifacts provide one more piece of evidence that changes the way we think about the origin and spread of new stone tool technologies. And intriguingly we made our discovery based on artifacts that had been excavated decades ago.

Archaeologists have identified five modes humans have used to make stone tools over the last 3 million years. Each mode is represented by a new stone tool type that is dramatically different from what came before. The appearance of each new mode is also marked by a big increase in the number of steps needed to make the new tool type.

One of these modes, Mode III, also called Levallois, is at the center of several big debates about human evolution. Levallois tools are the defining features of the archaeological period referred to as the Middle Paleolithic, or Africa’s Middle Stone Age. They are the result of a set of very specific steps of chipping a piece of stone to create similar-sized tools suitable to be shaped for a variety of purposes. These steps are remarkable because they are a much more efficient way to produce lots of useful cutting tools, with minimal wasted stone, compared to earlier technologies.

One of these debates is whether Mode III tools were invented in one place and then spread out, or independently invented in several different locations. Since the world’s oldest securely dated Levallois tools have been found in north Africa from around 300,000 years ago, it’s possible they spread out from there, carried by groups of early humans migrating across Europe and into Asia. On the other hand, finds of similarly early Levallois tools in Armenia and India support the idea of independent inventions of the technology outside of Africa. In China it has been hard to find evidence of Mode III tools until relatively late in the Palaeolithic period, approximately 30,000 to 40,000 years ago. That’s concurrent with when Mode IV (blade tools) appear there. Ancient people in China appeared to leap from Mode II (stone hand axes) to Mode III and IV at the same time. This suggests that Levallois
tools appeared in China when modern humans migrated in and brought these new technologies with them around 30,000 to 40,000 years ago.

Smithsonian