Stone fragments cast doubt on early human tools

Long-tailed macaques in Ao Phang Nga National Park use stone tools to open hard-shelled nuts.

The discovery in Thailand of accidentally produced stone fragments by wild macaques could well cause anthropologists headaches.

The latter believed until today that the sharp-edged cut stones they find particularly in East Africa were evidence of the beginning of the intentional production of stone tools, one of the characteristics of the evolution of the human species.

In fact, these stones are the primary evidence for the emergence of technology in our evolutionary line. This evidence is used to understand the behavior, cognition and subsistence strategies of early hominins, explain Tomos Proffitt and his colleagues, from the Max Planck Institute for Evolutionary Anthropology.

Examples of stone chips created by macaques.

However, long-tailed macaques in Ao Phang Nga National Park use stone tools to open hard-shelled nuts. During this process, they often break their hammers and anvils, so broken stones are widespread in their habitat. And they look a lot like the tools of our ancestors.

Many of these objects have the same characteristics as those commonly found in East Africa and identified as intentionally made stone tools in some of the oldest sites in this region, researchers at the Max Planck Institute for Evolutionary Anthropology in Germany note in a statement.

These researchers compared stone assemblages from the Plio-Pleistocene (3.3 to 1.56 million years old) to flakes produced by macaques to find that these fall within the technological range of manufactured artifacts by the ancestors of Homo sapiens.

In the absence of behavioral observations, the assembly produced by apes would be likely identified as anthropogenic in origin and interpreted as evidence of intentional tool production, the researchers say.

Our study shows that the production of stone tools is not the prerogative of humans and their ancestors, explains in a press release ;lead author, Tomos Proffitt, researcher at the Max Planck Institute for Evolutionary Anthropology.

The fact that macaques use stone tools to open nuts is not surprising, as they also use tools to access the contents of various shells, he adds.

“Interestingly, in doing so, they accidentally produce artifacts of their own that are partly indistinguishable from those of human lineage species.

—Tomos Proffitt, Max Planck Institute for Evolutionary Anthropology

Either way, anthropologists believe these accidental simian creations offer new insights into how the technique appeared among our earliest ancestors.

Furthermore, the origin of the latter may be related to similar nut-cracking behavior in Homo which may be much older than the oldest current anthropological documents suggest so.

Thus, in Homo species, the cracking of nuts, similar to what certain primates do today x27;hui, may be a precursor to the intentional production of stone tools that appeared later.

“This discovery shows how living primates can help us study the origin and evolution of human evolution. use of tools in our own lineage. »

— Lydia Luncz, Max Planck Institute for Evolutionary Anthropology

Details of this work are published in the journal Science ( in English).