Children and Chimps
Children Learn by Monkey See, Monkey Do. Chimps Don't. - New York Times
(If you don't have one of the NYTimes accounts annoyingly required to read the story, consider BugMeNot and its Firefox Extension)
The study quoted reports that when shown how to open a box, chimps can leave out causally unnecessary steps, while human infants tend to reproduce everything, even if they know it to be unnecessary. The researchers conclude that this imitation may enable the learning of complex new behaviours, which the child wouldn't understand at first sight, and thus couldn't analyse causally.
Most intriguing about this is that the other obvious explanation, that the children are trying to conform in a social situation with an adult, and are willing to give up efficiency to do so, may be the same thing. Culture and tradition, after all, are the codified learning of behaviors which do not seem to make immediate causal sense.