Chimpanzees show human-like rational thinking, study finds

Chimpanzees are capable of weighing evidence and updating their decisions in ways previously thought to be uniquely human, according to a new study published in Science, The Financial Times reports.

Led by Hanna Schleihauf of Utrecht University, the international research team observed up to 23 chimpanzees at the Ngamba Island Chimpanzee Sanctuary in Uganda. The experiments involved hiding food in containers and providing the animals with sequential clues of varying strength about the food’s location.

The chimps demonstrated rational behaviour by sticking with strong initial clues and switching choices when later evidence was more persuasive. They could distinguish between old and new information, ignore repeated but irrelevant hints, and even see through misleading cues such as pictures of food painted on containers.

Brian Hare, an evolutionary anthropologist at Duke University, noted that the findings indicate that “nonhuman apes have a spontaneous ability to weigh evidence of varying strengths, revise prior choices, and adapt when evidence is revealed to be unreliable.” Across the experiments, chimpanzees made rational choices two to three times more often than non-rational ones.

The study suggests that the cognitive abilities allowing humans to reason about the world are present, to some degree, in our closest living relatives—a notion first proposed by Charles Darwin and supported by decades of primate research. The findings also reinforce Jane Goodall’s long-held observations of chimpanzee intelligence and curiosity.

The researchers concluded that chimpanzees possess “genuine metacognitive capacities,” able to juggle concepts such as hypotheses, evidence, and causal relationships, putting them closer to humans in cognitive abilities than previously understood.

By Vugar Khalilov