A long-held belief about human uniqueness has been challenged by our closest animal relatives. A new international study has discovered that chimpanzees possess a sophisticated ability to think rationally, weigh evidence, and change their minds when presented with new information—a cognitive skill previously thought to be the exclusive domain of humans.
The research, conducted by scientists from several prestigious universities, involved a series of clever experiments. Chimpanzees were presented with two boxes, one of which contained hidden food. They were first given a clue about the food’s location, which could be strong (like seeing the food) or weak (like hearing a sound when the box was shaken). Later, they were shown new evidence that pointed to the other box.
The results, published in the journal Science, were striking. The chimpanzees didn’t just guess or stick stubbornly to their first choice. They evaluated the quality of the information. If the new evidence was stronger than the initial clue, they rationally switched their choice. They could even detect when a clue was misleading, such as a box containing only a picture of food, and would then change their minds accordingly.
“This kind of flexible reasoning is something we often associate with four-year-old children,” said Emily Sanford, a postdoctoral researcher at UC Berkeley. “It was exciting to show that chimps can do this too.” The findings suggest that the fundamental processes of rational decision-making, once considered a defining human trait, are shared with our primate cousins, blurring the line that separates human and animal cognition.
