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Re: origin of bats/reply 2 to TMK
On Jun 20, 2008, at 2:07 PM, Mike Habib wrote:
So the question is, if bats were climbing using all fours, why and
how would the change to using only the thumbs and folding the
other fingers under actually work? IMHO there has to be an
intermediate stage because if something is working right (climbing
hands) they don’t change without intervention.
This is an assertion, not really a robust conclusion.
No this is a question followed by red flag because a leap of logic
has appeared in traditional thinking.
There is not reason to think that climbing hands can't evolve dual
function under specific selective regimes.
Dual function? Name an analogous situation.
The fact that we can't imagine a particular story to go with it is
of limited importance in this regard. Mechanically, climbing with
only digit one, while folding the other digits clearly works (as
bats currently use this method).
But this is clearly secondary. Evolution always chooses the best
solution to a problem. Try climbing with only your thumbs or ask a
cat to do so and you'll see that's not the best solution.
To determine how a standard climbing hand gets to that point, we
need more fossil evidence and phylogenetic analysis.
True. We don't know the transition. But at the transition, bats were
at liberty to do something else with their hands.
Just assuming that there has to be a bipedal stage is not
Except that we have two examples of bipedal vertebrates that grew
wings. And bats are inverted bipeds. That's irrefutable. And their
outgroups were experimenting with holding prey in their forepaws.
There's your dual function.
Hey, I'm just the messenger. It's just a new idea. That's all.
Michael Habib, M.S.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205