When faced with a complicated puzzle box containing stickers or food, toddlers fare better than chimps or monkeys at getting to the goods. One reason, according to new research, is that children help each other. In this study, eight groups of 3- and 4-year-old children, eight groups of chimpanzees (Pan troglodytes), and one group of capuchin monkeys (Cebus apella) were given puzzle boxes that opened in three distinct stages, revealing rewards. After up to 53 hours with the box, few chimpanzees or monkeys completed all three steps, but about half the children solved the complete box after only 2½ hours. Moreover, the researchers found that when one child in a group solved a stage of the puzzle, they often told the others how to solve it  or let them watch the steps and imitate the solution—collaboration not seen among the chimpanzees or monkeys, who kept to themselves when puzzling over the box. This kind of cumulative culture, where generations build on the innovations of their forebears, has been observed only in humans. The new work, published today in Science, hints at one quality of human behavior that helps drive this difference.
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