Yes, but part of the idea that Wills proposes is that some genes (actually
exons and domains) are generally useful in the construction of proteins.
Things are getting better at evolving because they have developed, through
natural selection, a good set of "snap on tools" (his metaphor). They have
been useful for many situations in the past and will probably be so in
He even says that it explains some of the startling evolutionary convergences
we see in the fossil record, e.g. the mammalian and marsupialian radiations.