"The fact that rituals don’t make practical sense is just what makes them useful for social identification," writes Alison Gopnik in The Wall Street Journal (8/24/13). Americans, for instance, are alone in their use of utensils: "In fact, if you’re an American, chances are that you cut your food with your fork in your left hand, then transfer the fork to your right hand to eat the food, and then swap it back again. You may not even realize that you’re doing it. That elaborate fork and knife dance makes absolutely no sense … (Several spy movies have used this as a plot point)."
According to research by cognitive psychologist Christine Legare at The University of Texas, such "rituals are deeply rooted and they emerge early. Surprisingly, young children are already sensitive to the difference between purposeful actions and rituals, and they adopt rituals themselves. In a new paper forthcoming in the Journal Cognition, Dr. LeGare and colleagues showed 3- to 6-year-old children a video of people performing a complicated sequence of actions with a mallet and a pegboard." The basic task was to use the mallet to help manipulate the pegs.
Sometimes one person did it in a particular way twice, while in other sequences to people did it the same way simultaneously. When the children "saw the single actor, they were much less likely to imitate what the individual did," apparently seeing it as "a purposeful action." But when "they saw two people do exactly the same thing at the same time," they replicated their actions. The explanation is that "identical synchronous actions" indicated "that the two people were from the same social group." The implication is that we "learn as much from the irrational and arbitrary things that people do as from the intelligent and sensible ones."