We humans aren't the only ones who want to fit in. Researchers have discovered that chimpanzees, too, preferentially adopt their fellow chimps' way of doing things.

Andrew Whiten of St. Andrews University in Fife, Scotland, and his colleagues studied three groups of captive chimpanzees and the ways in which they assumed different techniques for obtaining food. The first group contained a high-ranking female that had been taught to retrieve food from an apparatus by using a stick to push a blockage away, thus freeing the food item. The second group also contained a female expert, but one that had been instructed to lift the blockage with the stick in order to release the treat. The third group was a control group and did not have a local expert. When the experts were reunited with their respective groups, the other chimps watched their activities at the food apparatus intently and learned to apply either the poking or lifting technique themselves. Members of the third group, lacking an expert to guide them, failed to figure out the contraption on their own.

For the most part, chimps in the first group initially stuck to poking and those in the second group stuck to lifting. But then, unexpectedly, some chimps discovered and began using the other strategy. When the food apparatus was reintroduced two months later, however, the chimps reverted to their group's normal way of doing things. In the case of those animals in the lifting group, this meant discarding a technique (poking) that is actually more natural for chimpanzees than lifting is.

"We have shown a non-human species conforming to a group norm, despite possession of an alternative technique that represents the norm of another group," the team writes in a report published online yesterday by the journal Nature. "Conformity fits the assumption of an intrinsic motivation to copy others, guided by social bonds rather than material rewards such as food." The findings suggest that this tendency was present in the last common ancestor of chimps and humans, and thus speak to an ancient origin for our own desire to conform.