Kids flex cultural muscles

Preschool kids angling for a reward display social skills that may, on a grander scale, turn human cultures into cauldrons of change and innovation.

Groups of 3- to 4-year-olds, but not clusters of chimpanzees or capuchin monkeys, solved progressively more complex tasks in a puzzle box by employing three key social strategies, say zoologist Rachel Kendal of Durham University in England and her colleagues. First, children who solved a task taught struggling peers what to do. Second, kids often copied what others did. And finally, task solvers frequently shared stickers they received as rewards with kids who hadn’t yet earned stickers. 

This package of social behaviors characterized four- or five-person groups in which at least two kids solved a three-stage puzzle and most of the rest reached stage two, Kendal’s team reports in the March 2 Science. Chimps and capuchins in groups of eight to 32 rarely got beyond stage one of the same puzzle, the researchers say. No evidence of teaching or sharing of food rewards appeared in these primates. Chimps copied others at the first stage but not at higher stages.

“The stark contrast in skills supporting cultural ability between children and both chimps and capuchins was surprising,” Kendal says. Her study is the first to use the same task to explore social learning in different species.

Previous studies of children’s problem-solving in groups have similarly focused on teaching, imitation and sharing, remarks anthropologist Joseph Henrich of the University of British Columbia in Vancouver. These behaviors critically enable human cultures to make rapid advances in knowledge and technology, he says. Further research needs to untangle precisely how this process works, Henrich adds.

Children’s puzzle-box successes may reflect other human mental specialties, such as reasoning with language and inferring others’ intentions, suggest psychologist Robert Kurzban of the University of Pennsylvania in Philadelphia and anthropologist H. Clark Barrett of the University of California, Los Angeles, in a commentary published in the same issue of Science.

In Kendal’s study, participants reached chutes containing stickers or food first by moving a sliding door to the left or right, then by pushing either of two buttons to move the door further in the same direction, and finally by turning a dial using one of two colored holes, releasing the door to slide still further.

After 30 hours, only one chimp mastered the puzzle box, but the strategies didn’t spread. After 53 hours, no capuchins cracked all three tasks, and only two solved two tasks.

After 2.5 hours, five of eight kids’ groups contained at least two individuals who had conquered the puzzle box, with most remaining kids in those groups solving two tasks.