Scientists prove that tools attributed to ancient humans were made by ancestors of capuchin monkeys

The study led by CONICET researchers questions the theory of specialists who maintain that the American population would have taken place between 35,000 and 50,000 years before the present.

Archaeologist Agustín Agnolín and paleontologist Federico Agnolín, CONICET researchers, demonstrated that 50,000-year-old tools – identified long ago in the “Pedra Furada” cave in northeastern Brazil – were made by ancestors of capuchin monkeys and not by humans, as some specialists maintain. The study was published in The Holocene.

One of the hottest debates in American archeology has to do with when the first humans entered the continent. Most researchers agree that the first Americans (Homo sapiens sapiens) would have arrived around 13,000 or 14,000 years before the present, crossing the Bering Strait, joining Asia with North America. However, a group of specialists who work in Brazil proposes that the American population would have been much older, possibly between 20,000 and 50,000 years before the present, and to confirm this, they maintain, among other arguments, that the tools found in the “Pedra Furada” cave and other sites in Northeast Brazil are of human origin.

“Our study shows that the tools from Pedra Furada and other nearby sites in Brazil were nothing more than the product of capuchin monkeys breaking nuts and rocks some 50,000 years before the present,” says F. Agnolín, also a researcher at the ‘Argentine Museum of Natural Sciences “Bernardino Rivadavia”’ (MACN-CONICET), and the “Azara Foundation.”

Agnolín and F. Agnolín decided to compare the stone tools found in Pedra Furada (supposedly from the first Americans) and those that capuchin monkeys make today. “The result was surprising: there was no difference between the supposed human tools from 50,000 years ago and those produced by monkeys today,” says A. Agnolín, a researcher at the Institute of Latin American Anthropology and Thought (INAPL).

The study led by CONICET researchers is in line with other very recent works in Brazil that show that capuchin monkeys use rock tools. They go to rounded rock quarries, known as “boulder”, and there they select a rock that they consider to be of adequate size and use it as a hammer together with a larger, flattened rock as an anvil in order to crack nuts. They also use tools to dig and get food.

In other cases, capuchin monkeys hit one rock with another and then lick the dust that is generated after the blows, possibly as a way to obtain minerals that are rare in their diet. The result is that the rocks used often break, generating rock fragments that are very similar to those produced by humans when carving stone tools”, A. Agnolín explains.

Besides, A. Agnolín points out that the tools found in Pedra Furada and other sites in the Northeast of Brazil are extremely simple in their manufacture and that they have never been made on rocks from other places. “That is, they always consisted of fractured pebbles, anvils, hammers, and jagged-edged rock fragments, but other types of tools never appeared. All these characteristics are indistinguishable from the tools used today by capuchin monkeys”, the archaeologist says.

In the same way, the CONICET specialists affirm, the ancient deposits of Brazil – Pedra Furada, Sitio do Meio, Toca da Tira Peia and others – absolutely lack any trace of human presence, such as the existence of hearths or remains of what constituted their diet.

“Our review of the evidence suggests that the ancient sites in Brazil do not actually belong to the first Americans, but are actually the product of monkey activity. This questions the hypotheses that proposed an excessively old settlement of South America”, indicates F. Agnolín. And he adds that the work also suggests that rock tool-using activities by capuchin monkeys and their ancestors would be extremely ancient.

“Our work reinforces the idea that the human settlement of this part of the American continent is more recent and is in line with the studies that determine its arrival some 13,000 or 14,000 years before the present,” concludes A. Agnolín.

References: Agnolín, A. M., & Agnolín, F. L. (2022). Holocene capuchin-monkey stone tool deposits shed doubts on the human origin of archeological sites from the Pleistocene of Brazil. The Holocene, 09596836221131707. 

By Bruno Geller