14 DAY TRIAL // We tend to see the apes that are closer to us as being more intelligent, like chimps and bonobos, while orangutans are seen like red clowns. This conception persists despite the fact that many tests have proven a high cognitive ability in this ape. Now they astonished scientists with an Aesop's fable-like situation, when the smart raven throws stones into a pitcher to raise the water level so that the bird could reach the water for drinking.
The apes were presented with a peanut floating deep down inside a transparent tube; the animals spat their drinking water into the tube to bring the treat to the top, where they could grab it. This is the first time when an animal has been found to use water as a tool in an intelligent way.
The research team led by Natacha Mendes at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has experimented on five Sumatran orangutans (Pongo abelii).
The orangutans received clear plastic tubes, each with a small amount of water along with a peanut, but out of the reach of the ape. They tried everything they could to reach the peanuts, from biting to hitting and kicking the tube. But in an average time of about nine minutes, the smart animals realized that adding extra water could solve the issue. The red apes started taking mouthfuls of water from their drink dispenser and spitting the liquid into the tube, raising the water level inside till the peanuts reached an accessible point.
"This seems to be insightful behavior because they haven't seen this test before. And as soon as they got the idea they continued to do it." said Mendes.
Each orangutan was given the peanut-containing tube 10 times. By the tenth attempt, they started to do the job in just 30 seconds. In control experiments, the team taped the peanut to the top of the tube. In this case, the apes just grabbed the food with their hands, without spitting.
"Archer fish (Toxotes jaculatrix) can spit water at flies to knock them into the water for eating. But the orangutans' use of water represents a more sophisticated behavior. There's no comparison. The apes have a conscious idea of what they are doing and consider other options, such as kicking the tube. With orangutans we are talking about a flexible strategy - that's the big difference." noted Mendes.