Captive orangutans can use stone tools without minimal guidance from humans, researchers reported today. As well as an affirmation of the orangutan’s intelligence, the finding has implications for understanding how and when stone tool use evolved in ancient human ancestors.
The research took place in two parts: one experiment took place at Kristiansand Zoo in Norway and another at Twycross Zoo in the UK. The experiment in Norway tested whether orangutans (Pygmy Pongo) would be able to hammer a stone core – a key step towards making a tool – and open a container using a sharp flint shard. The experiment in England tested whether monkeys could learn tasks by watching others do them. The team’s research is published in PLOS One.
“Our study shows that, despite the fact that orangutans do not use stone tools in the wild, they can use them when provided to them in captivity,” said researcher Alba Motes-Rodrigo. the University of Lausanne in Switzerland. and the study’s lead author, in an email. “Therefore, the failure of orangutans to use stone tools in the wild is due to a lack of need or opportunity (as they are primarily arboreal) rather than a lack of ability. “
Orangutans in Norway used the concrete hammer, but only to hit the walls and floor of their enclosure, not the stone provided to them. In the second experiment, in which they were given a ready-made flint flake, a monkey named Loui successfully used it to open a silicone skin to access food. Researchers say this is the first time an untrained, uncultured orangutan has demonstrated the ability to cut objects. (The “enculturated” orangutans were exposed to human social and material culture, meaning they might process objects differently from a completely wild ape.)
In England, three female orangutans learned how to strike a stone to create a flint shard. After watching the demonstrations, a monkey named Molly managed to hit the edge of the rock. No shards came off the stone, although the strikes targeted the correct area.
“When presented with a man-made snowflake, a naive orangutan spontaneously used it as a cutting tool to open a puzzle box, providing proof of concept that cutting (or drilling) at the Using sharp tools is part of orangutans’ spontaneous repertoire,” the researchers wrote. “Taken together, our findings suggest that two prerequisites for the emergence of early lithic technologies – lithic percussion and the recognition of sharp stones as cutting tools – may be deeply rooted in our evolutionary past.”
Motes-Rodrigo added in his email that while the research does not prove that the last common ancestor of orangutans and humans used tools, it does show that “a species of monkey that does not use tools stone tools in nature and which diverged from our lineage 13 million years ago, spontaneously engages in stone-related behaviors crucial to stone tool making. the instinct to use tools can go back as far in our shared history, although no ape is known to carve rocks the way humans can.
Evolutionary biologist Sofia Forss noted in an email that the apes, because they live in a zoo, may have been exposed to human activities, including our use of various objects, even though they didn’t not specifically trained to use stone tools. “We are still left with the crucial question of why this behavior does not occur in wild apes,” wrote Forss, a primatologist at the University of Zurich. “Especially chimpanzees, despite their vast repertoire of tool use and terrestrial lifestyle.”
The team’s findings follow other news about tools from the simian world: Last week, a study published in Current Biology posed that chimpanzees can use insects for first aid, evidence of a unique application of resources as well as a demonstration of altruistic behavior.
Primates aren’t the only animals to use tools – birds, pigs and even crocodiles have shown the ability to do so – but orangutans are discovering the same tools that our ancestors relied on to keep the species still alive. closer to us than we already knew they were.