We're having a little discussion about complexity in the comments from my post of last Friday [Vertebrate Complexity Is Explained by the Evolution of Long-Range Interactions that Regulate Transcription?]. I pointed out that many scientists just can't come to grips with the idea that humans aren't much more complicated than other animals. We are not special. I call this The Deflated Ego Problem.
One of the minor arguments in favor of human exceptionalism is the idea that we (mammals?) have more cell types that other species. Therefore, we are more complex. The number that's often bandied about is 210 cell types. PZ Myers debunks this myth (once again) in Methinks it is like a fox terrier". I love it when people like PZ make oblique references to Stephen Jay Gould as he does in the title. If you don't know what this has to do with fox terriers then you're in for a double treat.