(ORDO NEWS) — From ants to fish to crows, many animals use rocks as tools. But until recently, only humans and our hominin relatives had recognized archaeological evidence for the use of stone tools.
The scientific community now accepts that hominins have company. So which species have entered, so to speak, their own archaeological “Stone Age”?
Tools of labor in primates
Turns out Stone Age isn’t the most exclusive club.
They were also joined by chimpanzees, capuchin monkeys and long-tailed macaques: archaeological finds confirm that they used stone tools in the past. Sea otters might be next.
In every primate species, tool use is a socially learned behavior. “It became part of their culture,” said Katharina Almeida-Warren, a primatologist at the University of Oxford who studies chimpanzees.
Different groups use different instruments. Some groups of chimpanzees, for example, use a hammer stone thrown on an anvil stone to crush nuts.
Chimpanzees (Pan troglodytes) have used the hammer and anvil for thousands of years. Chimpanzees in the Ivory Coast wielded these tools 4,300 years ago.
“The stone age of chimpanzees predates the emergence of settled farming villages in this part of the African rainforest,” the researchers write in their paper.
Capuchin monkeys (Sapajus libidinosus) in Brazil also use stone tools to crack nuts; researchers have discovered nut cracking stones used by capuchins up to 3,000 years ago.
Their instrument styles have changed over the millennia in response to food.
Then, on a beach in Thailand, a team of scientists discovered stone tools that were once used by Burmese long-tailed macaques (Macaca fascicularis aurea) to open shells.
These tools were likely used between 1950 and 2004.
Is it true that some species are smarter than others?
It is not clear how these primates came to use stone tools.
In the case of chimpanzees, early stone tools suggest that their “material impact culture” was inherited from a common ancestor between humans and chimpanzees, the scientists write.
However, it is also possible that humans and chimpanzees learned to use stone tools independently; this seems to be the case for other animals known to use stone tools.
Thiago Falotiko, a biologist and primatologist at the University of São Paulo, points out that entering the Stone Age does not mean that the group will follow a human development trajectory anytime soon.
It also doesn’t mean that stone tool users are necessarily smarter than other animal tool users. “Rocks, trees and leaves are used just as actively,” he said.
However, it is stone tools that are especially valuable to the research community because they are durable.
It is important for archaeologists and anthropologists to know that primate tools may appear during excavations.
Shards of the past
In 2022 a team from Argentina hypothesized that the 50,000-year-old “human settlements” in Brazil were actually created by capuchin monkeys.
The researchers found that the stone tools in question, made from quartzite and quartz pebbles, are strikingly similar to those currently being made by capuchin monkeys in Brazil’s Serra da Capivara National Park.
“This article is far from definitive,” said Falotiko, explaining that the practical analysis has still not been done.
But if this hypothesis is correct, this hypothesis would extend the archaeological record of Capuchin stone tools by thousands of years, continuing the debate about when humans settled in South America.
Even when it is clear which tools belong to which species, non-human tools can provide a lot of useful information in other ways.
Almeida-Warren noted that the oldest hominin-made tools, at 3.3 million years old, were unearthed in part because primate tools have given archaeologists new ideas about what to look for.
According to Katarina, chimpanzees, for example, use not only stones, but also long pieces of bark to catch termites; they also resort to the help of medicinal plants for the treatment of wounds. “In many cases,” she said, “plant tools are actually more complex than stone ones.”
Non-human archeology may also shed light on the behavior of these species over time.
For example, at the ancient sites of the Capuchins, Falotiko learned that monkeys have adapted their tools for processing various foods over the centuries.
Afterwards, the researchers hope to learn the history of yet another tool-using animal: sea otters.
So, researchers from California observed how sea otters break open mussels on stones. Scientists have distinguished scratch marks on sea otters’ “anvil” rocks from footprints made by humans.
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