DNA constructs protein brains with reward signals that have a long-distance correlation to reproductive fitness, but a short-distance correlation to organism behavior. You don’t have to figure out that eating sugary food in the fall will lead to digesting calories that can be stored fat to help you survive the winter so that you mate in spring to produce offspring in summer. An apple simply tastes good, and your brain just has to plot out how to get more apples off the tree.
