In broad outline then, the neutral theory does a pretty good job of dealing with at least some types of molecular data. I'm sure that some of you are already thinking, ``But what about third codon positions versus first and second?'' or ``What about the observation that histone loci evolve much more slowly than interferons or MHC loci?'' Those are good questions, and those are where we're going next. As we'll see, molecular evolutionists have elaborated the basic framework3 in the last thirty years, but these basic principles underlie every investigation that's conducted. That's why I wanted to spend a fair amount of time going over the logic and consequences. Besides, it's a rare case in population genetics where the fundamental mathematics that lies behind some important predictions is easy to understand.4