types of organization

John Grehan jrg13 at PSU.EDU
Fri Feb 4 13:27:57 CST 2000

 I think it is a fundamental point that, from an evolutionary
>perpsective, taxa derive their identity from their history. Humans are not
>animals because we have or dont have any particular characters; those are
>only guides. We are animals because we are descendants of the common
>ancestor of Animalia.

>Tom DiBenedetto

We seem to have a closet Croizatian here. Croizat (1964) argued extensively for
this point of view under the concept "type of organization". He certainly
was at the
most outspoken proponent of viewing evolution and its course in this way
he was generous to give credit to similar views held even by his opponents such
as Simpson).

Nothing that can ever happen in the further evolution
>of our lineage will ever cause any of our descendants to not be an animal.

Another very precise point used by Croizat. He used the example of bird
returning to water (penguin) that remains a bird rather than becoming a fish.

>It is a matter of defintion.

Which may mean that definitions really don't matter all that much.

 That is why it is so frustrating sometimes to see e.g.
>so-called "evolutionary systematists" try to deny that birds are reptiles.

And humans are mearly a strange sort of terrestrial fish, or a colony of
protozoans. In a strange sort of way the creationists are right - there
really has been no "macroevolution" - we are still single celled animals
and so we have not evolved from one "kind" to another etc.

>If taxon 3 were the primoridal mammal, and taxon 1 was the primordial
>monotreme and taxon 2 the primordial therian, then is it not the case that
>all three are part of the higher taxon Mammalia?

"Mammalia" is the ancestor at this level of organization.

When Croizat was asked (in 1974) how he got into taxonomy he responded:

"Taxonomy was just a necessary counterpart of the work I was doing. You
must call a certain plant by a certain name, a certain animal by a certain name.
Naturally you come along and you dabble into taxonomy out of necessity.
The laws of nomenclature are imposed upon your attention by that. In other
words, you try to reorganize, or better to say, organize your thoughts along
definite lines and anming things properly; a regard for semantics of a
particular kind in this particular field is connatural to the work."

John Grehan

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