(ORDO NEWS) — Scientists from Germany and Spain have concluded that untrained orangutans can perform two basic steps in the sequence of using stone tools: making a tool from a core and using a cutting edge.
Early stone tools, and in particular sharp tools of similar material, are an important milestone in human evolution. The manufacture and use of such tools significantly expanded the ecological niche of our ancestors – they had new food resources.
True, scientists still do not know how these early stone technologies arose and what behavior became the starting point for their systemic production.
One approach to answering this question is to study the stone tool-making abilities of our living relatives, the great apes. Chimpanzees have been known to use stones to crack nuts, but primates have not intentionally made tools.
Scientists from the Universities of Barcelona (Spain) and the University of Tübingen, as well as the Max Planck Institute for Evolutionary Anthropology (Germany) conducted experiments with five orangutans from the Norwegian and British zoos and learned more about their ability to create stone tools.
Two young males participating in the experiment had a family: a female and a newborn cub. It is also known that both males were raised by orangutans, not humans. Animals had contact with zoo workers only through the bars of their enclosure.
They were trained only in veterinary procedures (this is a common practice for zoos: it consists in the fact that the animal, for example, does not resist when examined by a doctor). And they were not given any special training in any skills.
Both orangutans received boxes of delicious fruit bait. To get to them, it was necessary to cut the rope, made from various types of durable fabric.
Each animal was given a special hammer and a prepared stone core. Both orangutans took hammers and spontaneously struck the walls and floor of their enclosure with them, but neither directed the blows at the stone to make a sharp tool out of it for cutting the rope.
However, in the second experiment, the researchers provided the primates with a sharp stone tool (scale) made in advance by a person, and – lo and behold! — one of them guessed to cut the rope.
This is the first time that untrained primates have been able to cut objects, scientists say. Three females participated in the third experiment.
They were shown how to hit the stone core to get a silicon flake. After that, one of them tried to repeat the actions of the experimenters, continuing to hit the stone with a hammer, directing the blows to the edge, as was demonstrated.
This is also the first study to show that untrained orangutans are able to spontaneously use and make cutting stone tools without clear guidance from humans, the authors note.
Therefore, scientists believe that such behavior could have appeared even in a common ancestor of these primates and humans, who lived from ten to 13.5 million years ago.
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