I still believe that the most interesting problem in the world is the biological basis of behavior. I had to serve on a jury recently, and the biggest thing I took away from the experience was a new appreciation for the study of behavior. The whole case basically revolved around understanding why different people in different positions act or perceive things the way they do, and using logic to make sense of a large and complicated portrait of social interaction. And I just began to realize that the subject really is endlessly fascinating to me… the things we do, and why we choose to do them. So many fascinating things that are going to require decades to understand nest within the problem of understanding behavior itself: decision-making, emotion, reward, punishment, value, the generation of action, perception, social behavior. There are larger problems out there, I’m sure, but none that intrigue me more on a daily basis.