14 DAY TRIAL // We pride ourselves on our high intelligence and we say that this is the main trait that sets us apart from apes. But why are we more intelligent? A new research made by a team at the Max Planck Institute for Evolutionary Anthropology in Leipzig on 106 juvenile and adult chimpanzees (living in sanctuaries in Uganda and Republic of Congo), 32 orangutans (at an Indonesian center), and over 100 2.5-year-old German toddlers points that our higher social intelligence makes the difference, permitting us to build on our complex behavior.
The subjects underwent series of tests 3 to 5 hours long. Six tests checked social ability, meaning that one of the researchers was involved and the children, chimps, or orangutans had to detect social cues.
10 were physical, such as detecting a hidden reward (food for the apes and toys for the children).
Children did not outperform apes in these tests; moreover, they were outperformed by the apes on 3 physical tests.
For example, when the team placed three raisins under one cup and two under another, both children and chimps chose the cup with more raisins. But when the researchers moved in front of their subjects two raisins from a cup into another that already contained two raisins, the chimps figured out the difference and chose the bigger reward, while children often did not.
But in the realm of social cognition, the toddlers were much more skilled. When they saw a researcher extracting a toy from a plastic tube, the children copied the action and got the reward.
But "if you demonstrate to a chimpanzee or orangutan, ... they try to get it out by their own means without copying," said Esther Herrmann, Ph.D. Student.
Other social tests also included "spying" on the gaze of the researcher, staring or other clues pointing out where the reward could be. "Among the social tasks, the children succeeded about 74% of the time; the chimps and orangutans, about a third of the time," the team reported in one issue of Science.
"Human children are not overall more intelligent than other primates but have specialized skills of social cognition," concluded Herrmann.
Not everybody agrees to that. Primatologist Marc Hauser of Harvard University signals that the children, accustomed to people, were more likely to respond, while the apes may have not been interested in doing this.
"The chimps and orangutans were more interested than the children were in approaching a human they had not met before." argued Herrmann.
"Another concern is whether the children outperformed on the social tasks not because the tasks were social but because they were inherently more difficult and abstract than the physical challenges. If so, that might have stumped the chimps and given the children an unfair advantage," said Daniel Povinelli, director of the Cognitive Evolution Group at the University of Louisiana, Lafayette.