Anybody who has been stuck without a bottle opener at a beach picnic knows the value of future planning. But is planning a uniquely human trait? Perhaps not. A new study shows that bonobos and orangutans can save tools that help them access a future snack. The findings suggest that cognitive precursors to human foresight may have evolved in great apes more than 14 million years ago.
To test bonobos' and orangutans' ability to plan ahead, psychologists Nicholas Mulcahy and Josep Call of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, presented the apes with situations in which they had to save a food-getting tool for a later time. First, the animals spent five minutes in a room with two suitable and six unsuitable tools for a food apparatus that the apes could see but not touch. Then, the researchers led the animals to a neighboring room, letting them take along any tools they wished, and left them there for an hour while an attendant cleared out the remaining tools from the test room. When the apes returned to the test room, the apparatus was accessible, and the apes could get food from it as long as they had the right tool with them.
After a few trials, most of the animals started carrying the right tool with them. The researchers got similar results even when the apes were ushered out to a sleeping room and kept there overnight. Finally, to ensure that the animals were not making a simple association between tool and the reward, the researchers removed the apparatus from the test room before the animals returned for the second visit but still rewarded them if they came back with the right tool. The animals started bringing wrong tools more frequently under this condition, confirming that their act of saving the tool for later use in the prior experiments had been a form of planning behavior, the team reports tomorrow in Science.
The results are "groundbreaking," says cognitive psychologist Thomas Suddendorf of the University of Queensland in Brisbane, Australia, who notes that the findings provide "a starting point from which we can begin to reconstruct the evolution of the human mind." A major implication of the study, he says, is that "our extraordinary abilities of planning for the future did not evolve entirely de novo."