René Descartes thought human beings were pretty special. And we are. But it also led him to say a lot of things that were wrong. We’re only special to a point.
He said, “I think, therefore I am,” and that was wrong. He also said that animals, as opposed to humans, were automatons—machines without souls that act “mechanically” and are “destitute of reason.” In case there was any lingering doubt, new evidence shows he was wrong about that, too.
The latest nail in Descartes’ coffin is a new study published yesterday in the open access journal, PLoS One, demonstrating that monkeys, like humans, can learn more efficient ways to use a single tool by watching each other.
Led by Shinya Yamamoto at Kyoto University’s Primate Research Institute, a team of researchers gave drinking straws to a group of chimpanzees and directed them to clear, wall-mounted juice boxes; the chimps, who were tested in isolation from one another, proceeded to spontaneously employ two separate techniques for using them.
Five of the nine chimps in the experiment used what researchers called a “dipping” technique to get the juice, which involved inserting the straw through the small hole in the juice box and sucking the juice out of the straw. Here’s one using the dipping technique. He almost figures out how to use it properly on his own, but not quite:
But researchers found when the “dipping” monkeys were exposed as a group to a fellow chimp or human being who used a straw in the more efficient way—the “sucking” method—all five changed their technique. With the clear juice boxes, they could see the difference in efficiency. Here are few of them figuring it out:
Scientists have known for a while that chimps can learn how to use tools by watching. But what distinguishes the results of this experiment from others is that it exhibits a more complex form of “social learning.” In this case, it wasn’t just a matter of giving a monkey a juice box and a straw and showing the monkey how to use it. That’s just “monkey see, monkey do.”
As the researchers describe the previous findings:
Previous experimental studies have revealed that chimpanzees can socially learn different techniques. However, while most of these studies have focused on the social transmission of behavioral techniques not involving tools, others reported social learning of two optional tool-uses whose performance differed in the target location of the tool-use action. Based upon the strict criteria of same tool, same target, and same location, there is to date little experimental evidence for social transmission of tool-use techniques in non-human animals, even in chimpanzees.
Monkeys in this experiment, rather, made clear inferences by observing demonstrably different ways to use the same tool to achieve a specific task. That’s a complex act of discernment—the kind of reasoning we humans, like Descartes, assumed for a long time fell strictly within our purview.
Data, image and video source: Shinya Yamamoto, Tatyana Humle, Masayuki Tanaka. Basis for Cumulative Cultural Evolution in Chimpanzees: Social Learning of a More Efficient Tool-Use Technique. PLoS ONE, 2013; 8 (1): e55768 DOI: 10.1371/journal.pone.0055768