I was once watching a herring gull through binoculars side by side with Bill. In those days, a herring gull could not scratch itself without one of us asking why natural selection favored that behavior. In any case, I offered as an explanation for the ongoing gull behavior something that was nonfunctional and suggested that the animal was not capable of acting in its own self-interest. Bill said quietly, “Never assume the animal you are studying is as stupid as the one studying it.” I remember looking sideways at him and saying to myself “Yes sir! I like this person. I can learn from him.