[ExI] Multiplicity of similar species: what's the mechanism/explanation?
max at maxmore.com
Mon Sep 28 22:25:18 UTC 2009
The Angry Evolutionist
By Richard Dawkins
(1) Dawkin says: "My favorites, however, are the
free-living turbellarian worms, of which there
are more than 4,000 species: that's about as
numerous as all the mammal species put together."
That made me think again about the curious fact
(I least I think it's a fact, without checking)
that there are vastly more species of insects
(especially ants) and arachnids as there are
mammals or "more complex" creatures. I realized
that I don't really know why that's the case.
Right now I'm too lazy to try to find an answer
in my biology books. I can make some guesses
(like "a simpler/smaller genome varies more, and
each variant finds sufficient room in the same
ecological niche"), but I'd like to hear if there
is a well-developed and compelling explanation.
(2) A quite different thought from the foregoing:
Why isn't Dawkin's question (in his 8th
paragraph) answered (at least somewhat plausibly)
by creationists with this?: "Because tapeworms
have no skeleton" I'm not sure he can really
conclude that "This argument, at a stroke,
completely and finally destroys the creationist
case that the Precambrian gap in the fossil
record can be taken as evidence against
evolution." -- until he addresses the skeleton point.
Indeed, right after Dawkin's has made his argument, he comments:
"Probably, most animals before the Cambrian were
soft-bodied like modern flatworms, probably
rather small like modern turbellariansjust not
good fossil material." Dawkins (rightly) says the
creationists can't have it both ways, but isn't
he having it both ways here? He's (a) using the
tapeworm example against the creationists -- a
case that seems to require that we should expect
ready fossilization despite their lack of a
skeleton, and also (b) explaining the gaps in the
fossil record on the basis that most pre-Cambrian
creatures (or "evolutures"!) were "soft-bodied".
Of course, I'm very sympathetic to Dawkins, but
his argument, as presented, bothers me. Am I missing something?
(For the record, I have read no book and not much
else by Dawkins since The Selfish Gene. Has
anyone yet read his latest: The Greatest Show on
Earth: The Evidence for Evolution?)
Max More, Ph.D.
Extropy Institute Founder
max at maxmore.com
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