Is planning ahead a uniquely human capacity? Researchers have now found that, although apes cannot plan their vacations, they can make short-term plans. Bonobos and orangutans can save tools that help them access food in the future.

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 tool in order to be able to access food at 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.

Researchers wanted to be certain that the animals were not simply making an association between a tool and the reward. So, they 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, thus confirming that their act of saving the tool for later use in the prior experiments had been a form of planning behavior.

This study suggests that we share the capacity to plan with the great apes and that the difference between us and them in this aspect is only quantitative and not qualitative - we are better planners and can plan longer ahead. This also shows that the ability of foresight evolved more than 14 million years ago.

This experiment is interesting because it tells us not only what apes can do, but also what they can imagine and think about. In order to save a tool, they have to have a mental model or representation of how the food apparatus worked. They didn't just go by trial and error each time - they used their prior experience with the apparatus in order to understand the apparatus so they wouldn't need to trial and error. So, it's not that they simply found themselves each time having to face yet another challenge of getting food from an apparatus, the way one has to face and cope with a novel external situation; they used their prior experience to model part of the external situation in order to better cope with it.

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."