Reblogged from Ann Gauger.
Comparing DNA sequences and estimating by how many nucleotides we differ from chimps doesn’t tell us much about what makes us human. Many of those nucleotide differences have no effect, because they are the product of neutral mutation and genetic drift. While these neutral mutations may affect the over-all mutation count, they don’t answer how many mutations are required for the transition from chimp-like to human.
This problem is analogous to one we examined concerning protein evolution last year in the journal BIO-Complexity (Gauger and Axe 2011). Converting one protein to another’s function can be viewed as a version, in miniature, of converting one species to another. But it is much easier to convert proteins than species.