Re: [asa] DeHaanıs theory of ³ Macro-Development²

From: PvM <>
Date: Tue May 08 2007 - 22:49:48 EDT

Keith Miller has addressed this, it seems that the top down/bottom up
may be more of a confusion as to how the assignment of taxonomic
categories happen.

Dawkins also addressed this issue in Unweaving the Rainbow

I am not sure why this top-down bottom-up is causing so much
controversy that many Creationists have taken the 'argument' as being
somehow anti-Darwinian.

This second idea, which I shall call the branch point explosion
hypothesis, is controversial. It is compatible - just - with what I
am calling the standard neo-Darwinian model of species divergence.
We've already agreed that, as we trace any pair of modem phyla back
in time, we eventually converge upon a common ancestor. My hunch is
that, for different pairs of phyla, we'll hit the common ancestor in
different geological eras: say, the common ancestor of vertebrates
and molluscs at 8oo million years ago, the common ancestor of
vertebrates and echinoderms at 600 million years, and so on. But I
could be wrong, and we can easily accommodate the branch point
explosion hypothesis by saying that, for some reason (which is
interesting enough to need investigating), most of our backward
tracings happen to hit their respective common ancestors during the
same relatively short geological period, say, between 540 million and
530 million years ago. This would have to mean that, at least near
the beginning of that 10- million-year period, the ancestors of the
modem phyla were nowhere near as different from each other as they are
today. They were, after all, diverging from common ancestors at the
time and were
originally members of the same species.

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Received on Tue May 8 22:50:25 2007

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