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RE: organic conversations



Mickey Rowe wrote:


> Personally I think that sort of argument doesn't merit a lot
> of attention (it's different from David's objection to Tim's useage of
> "homology" because -- as many people tried to point out 20 years ago
> -- molecular biologists did the world a disservice by clouding the
> concepts that the word "homology" was coined to describe...) 


I think this is a little harsh, given that the term 'homology' was conceived at 
a time when there was no real concept of evolution (not in the Darwinian sense, 
anyway).  Owen (1834) defined homology as "the same organ under every variety 
of form and function".  As one molecular phylogeneticist puts it "Owen’s 
definition of homology emphasizes structure and location rather than ancestry." 
(Fitch, 2000).  Thus, any definition of homology that has an evolutionary 
component (including 'shared ancestry', which is its current usage) is a 
re-invention from Owen's original concept.  The re-invention was completely 
justified, given our current understanding of how homology arises.  But it's a 
re-invention, nonetheless.  In this, molecular biologists are no more guilty 
than organismal biologists.  Molecular biologists recognize that certain genes 
or proteins have a common ancestry, just as organismal biologists recognize 
that certain organs or appendages have a common ancestry.  

Refs.

Fitch, W.M. (2000). Homology: a personal view on some of the problems.  Trends 
in Genetics. 16: 227-231.


Cheers

Tim
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