<<I think gradual change is incapable of explaining the major morphological
transitions. (but a simple change in material flow in the leg of a chick
embryo turns his legs into lizard legs) Thus punc-eq + the recent
discoveries in developmental biology are required for those transitions.>>
Yes, PE is truer to the data than the blind watchmaker thesis, but what it
gives up is the ability to explain adaptive complexity:
"If adaptive complexity is to be explained at all, it must be by a model like
that provided by Dawkins. Gould can discard that model only at the cost of
leaving adaptive complexity unexplained. Probably that is why Gould is evasive
about whether he is rejecting the Dawkins model or merely supplanting it with
other kinds of evolution.
"Perhaps the best example of the incompatibility of empirical and blind
watchmaker evolution is the Cambrian explosion, which is memorably pictured in
Gould's book Wonderful Life. Nearly all the animal 'phyla' (basic body plans)
appear suddenly and without apparent ancestors in the rocks of the Cambrian
era, dated around 540 million years ago. These animals are all complex
multicellular organisms, with highly complex adaptations like the famous
trilobite eyes. Where did these complex features come from? Before the
Cambrian era, with few exceptions, we have evidence of nothing but simple,
unicellular life.
"If one assumes that a process of gradual, blind watchmaker evoluiton produced
the Cambrian phyla, then one has to assume also that a universe of
transitional species that once lived on the earth vanished mysteriously from
the fossil record. Gould, a paleontologist who refuses to treat the fossil
record so cavalierly, can only delcare that the transitionals (or at least
most of them) never existed and that something called a 'fast-transition'
filled the gap.
"Gould is faithful to the observable evidence, where a blind watchmaker
theorist is not, but the price he has to pay is that he has only an empty term
to account for the complexity."
[Johnson, Reason in the Balance, pp 87-88]
Gould, by the way, is refusing to debate PJ. In the works, though, is a debate
with Niles Eldredge.
Jim