Since the opportunities for XS to agree (in advance) with PZ Myers don’t come along too regularly, it’s worth seizing upon those that do. For anyone who thinks cladistics are important, this point is worth strongly defending:
There are multiple meanings of “fish”. We can use it to refer to specific species or an extant category of animals: salmon are fish, halibut are fish, herring are fish. No one objects to that, and they all understand that if I said “humans are still salmon”, that would be wrong. […] But another way the term is used is as a descriptor for a clade. A taxonomic clade is a “grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor”. […] So, for instance, humans belong to the mammalian clade, which includes mice and cats and cows. If we have transhuman, part-cyborg descendants, they will still be mammals, because, note, by definition a clade must include all the descendants of an ancestor. We’re trapped! There’s no way our progeny can exit the clade!
In fact, it’s such a sound point, it’s worth generalizing.