Science Alert reports:

Chimpanzees can change their minds when the facts no longer support their previous beliefs – a rational level of thinking that was once considered uniquely human.

In a series of experiments designed to test the metacognition of these fascinating apes, psychologist Hanna Schleihauf of Utrecht University and her colleagues observed, for the first time, how chimpanzees can weigh different kinds of evidence – and change their beliefs in response to a stronger argument.

“This is really the strongest and hardest test for this understanding of so-called second-order evidence,” Schleihauf told ScienceAlert. “I think we have the evidence that we can say, okay, no, rationality in its fundamental form is not uniquely human, but we also share some basic processes of this with chimpanzees.”

It’s the Aristotelian school of philosophy that considers humans the “rational” animal – the one species on Earth with the capacity for reasoned decision-making. In recent years, however, we have started to learn that this assumption may be hubristic, with many animals demonstrating levels of intelligence Aristotle may have thought beyond them.

One putative defining characteristic of human thinking is rationality. This, for the purposes of this research, is defined as the ability to form beliefs about the world based on evidence; but, when new evidence emerges, a rational being can weigh up the two sets of evidence and, crucially, revise their beliefs when the second-order evidence about the evidence is stronger. [Continue reading…]