I drove into New Haven on a recent morning with a burning question on my mind. How did my daughter do against the chimpanzees?

A month before, I had found a letter in the cubby of my daughter Charlotte at her preschool. It was from a graduate student at Yale asking for volunteers for a psychological study. The student, Derek Lyons, wanted to observe how 3- and 4-year-olds learn. I was curious, so I got in touch. Mr. Lyons explained how his study might shed light on human evolution.

His study would build on a paper published in the July issue of the journal Animal Cognition by Victoria Horner and Andrew Whiten, two psychologists at the University of St. Andrews in Scotland. Dr. Horner and Dr. Whiten described the way they showed young chimps how to retrieve food from a box.

The box was painted black and had a door on one side and a bolt running across the top. The food was hidden in a tube behind the door. When they showed the chimpanzees how to retrieve the food, the researchers added some unnecessary steps. Before they opened the door, they pulled back the bolt and tapped the top of the box with a stick. Only after they had pushed the bolt back in place did they finally open the door and fish out the food.