Evolution? Can anyone really believe this?

Douglas Rhoads DRHOADS at MERCURY.UARK.EDU
Mon Jun 19 10:08:47 EST 1995


> To:            molecular-evolution at net.bio.net
> From:          griffin at mailbox.syr.edu (David H. Griffin)
> Subject:       Re: Evolution? Can anyone really believe this?
> Date:          19 Jun 1995 13:49:54 GMT

> In article <1995Jun16.134129.17490 at galileo.cc.rochester.edu>
> ttha at uhura.cc.rochester.edu (Tom Thatcher) writes:
> 
> > 
> > I think I answered most of this already.  I want to correct a
> > misconception, though, it that cells do not move to their location, 
> > as you seem to suggest, rather, location determines fate (mostly).  
> > A newly divided cell in the embryo's tail doesn't think to itself,
> > "I'm a brain cell, better get a move on."  
> > 
> I think that cellular movement is an important component of
> development. Certainly in the cellular slime mold, Dictyostelium and
> relatives, cellular movement is an important determinant in
> differentiation and development. The fate of the individual cell,
> whether stalk or spore, is determined by the timing of its movement
> from the free-living amoeba stage into the multicellular animal, the
> grex or slug.
> 
> Animal embryologists could also supply examples of cellular movement
> during development. Certainly the flat fish, e.g. flounders, provide
> excellent examples of final form being the result of cellular, indeed
> entire organ, movement. The embryonic fish and early free-swimming
> stages are vertical fish with the eyes on two sides of the body. Later
> development results in the migration of the eyes putting both on the
> same side of the body. The fish now swims on its side and rests
> sideways on the ocean floor. 
> 
> David H. Griffin
> Department of Environmental & Forest Biology
> College of Environmental Science and Forestry
> 350 Illick Hall
> One Forestry Drive
> Syracuse NY 13210-2788
> e-mail: griffin at mailbox.syr.edu

 And what of migration of fibroblasts in animal development and wound 
repair?  How about the complete re-construction of an organisms body form at least 
twice in its development (Drosophila).  It isn't just fate maps 
determined by body location but a lot of cells have to get to the 
right spot first and then are affected by morphogen gradients, 
neighboring cells, etc.
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||Doug Rhoads              || Dept. of Biological Sciences||
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