50,000-year-old stone tools were made by monkeys, not ancient humans, discover experts

The tools could be some of the first evidence of human habitation in the Western Hemisphere

The work turned up stone shards made from quartzite and quartz cobbles that resembled simple stone tools. The oldest tools could be up to 50,000 years old and could be some of the first evidence of human habitation in the Western Hemisphere, reported Artnet news. However, the tools also bore an uncanny resemblance to the stone tools currently made by the capuchin monkeys at Brazil's Serra da Capivara National Park. 

Agnolín and F. Agnolín compared the stone tools found in Pedra Furada, which are supposed to be 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," said A. Agnolín, a researcher at the Institute of Latin American Anthropology and Thought.

Not monkeying around

As per the study, the capuchin monkeys select rocks from rounded rock quarries and use them as a hammer together with a larger, flattened rock and an anvil to crack nuts. They also employ tools to dig and get food.

Intriguingly, the monkeys also 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 explained.

The tools were "extremely simple" in their manufacture

A. Agnolín also mentioned how the researchers correlated the tools used by capuchin monkeys to the latest discovery.

The tools found in Pedra Furada and other sites in the Northeast of Brazil are "extremely simple" in their manufacture, and 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 tools never appeared. All these characteristics are indistinguishable from the tools used today by capuchin monkeys," the archaeologist said.

Another crucial hint lay in the fact that the ancient deposits of Brazil lacked any trace of human presence, such as the existence of hearths or remains of 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," indicated F. Agnolín. He added that the work also suggests that rock tool-using activities by capuchin monkeys and their ancestors would be extremely ancient.

The discovery could rewrite history

This finding also proposes that the American population would have been much older, possibly between 20,000 and 50,000 years before the present. Most researchers agree that homo sapiens would have arrived around 13,000 or 14,000 years before the present, crossing the Bering Strait and joining Asia with North America. 

"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," concluded A. Agnolín.

Study Abstract:

New World capuchin monkeys are well-known for their ability to solve problems using stone tools that have the characteristics and morphology of some human-made stone tools. The aim of the present contribution is to carry out brief comparisons between the Pleistocene archeological sites from Brazil (e.g. Pedra Furada, Sitio do Meio, Vale da Pedra Furada, Toca da Tira Peia) and capuchin-made stone tool deposits. Pleistocene sites from Brazil are characterized by the exclusive use of immediately available raw material, the predominance of unifacial flaking, and abundance of cortical flakes, together with the absence of blades and bifacial thinning techniques. In all these aspects, the sites resemble capuchin-made lithic deposits and lack a number of human attributes. In sum, based on positive and negative evidence we are confident that the early archeological sites from Brazil may not be human-derived but may belong to capuchin monkeys.