Human and ape phylogeny

David Williams dmw at NHM.AC.UK
Mon Apr 7 15:55:58 CDT 2003

Interesting. So in a non-evolutionary world vertebrates (homologue) =
Vertebrata (taxon), in an evolutionary world they do not. And in an
evolutionary world, Owen's derivation ('transformation') of vertebrate
parts from the archetype (ancestor) makes sense, whereas in a
non-evolutionary world (Owen's) they do not.

>This is indeed the point - and it goes back to Patterson, who (thought he)
>could distinguish "taxic" and "transformational" homology. In a
>non-evolutionary world, taxic homology (the presence of a homologous
>structure in a number of taxa) is indeed possible - in an evolutionary
>world, it is not. In an evolutionary world (and models do not enter, just
>evolution) homology describes a change from one state to another, and a
>full specification of a homology statement *needs* two states. There are
>no "concepts" that arise de novo - each character has had a state from
>which it developed.

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