JP has an interesting post, Why the regulatory changes vs. coding sequence changes debate is inane:
Here's the question we're supposed to answer: which are more important-- protein-coding changes or regulatory changes? And here's the problem with that question: how do you define important? Let's make a list of the ways humans differ from chimpanzees-- we walk on two feet, we have bigger brains, we have less hair, etc. etc. You can add your own if you like. If a protein-coding change gives us the bigger brain, but a regulatory change the lack of hair, who wins? Sure, you could argue about which trait contributes more to some notion of "human-ness", but frankly, who gives a shit? Both are pretty important.
Some of the comments are of interest. The "big picture" is that these debates about "sequence vs. regulation" or "selection vs. neutrality" are probably good for driving scientific research programs, and providing a nice backdrop for popularizations, but on the granular fine scale and the grand scale they are pretty irrelevant. The answer almost certainly is "somwhere in the middle," and partitioning the underlying parameters as purely (or predominantly) sequence or regulatory is probably semantic juggling in an era where such categories are going to be broken down by more fundamental levels of understanding.^1 But of course, there is the
existential question, what does it mean to be human?
Honestly, I don't think science is ever going to be up to answering the question with the sort of answer that this question truly begs for. Unfortunately, the sort of "essences" that humans need to believe in don't exist anywhere but in our heads. 1 - I think Dan Dennett did hit upon something when he asserted that natural selection is "substrate neutral."