Biological "Relativity" (was: Human and ape phylogeny)

Curtis Clark jcclark at CSUPOMONA.EDU
Sun Apr 6 22:23:50 CDT 2003

At 21:19 2003-04-06, Ken Kinman wrote:
>      Yes, chimps have evolved since their common ancestor with humans, but
>obviously a lot less than humans have.

Like I might tell my students, "Ask yourself which species is telling you
this." Yes, humans have a lot of autapomorphies, but "obviously"? Clearly
it is our autapomorphies that allow us to discuss the issue, but I would
suggest that we have always needed more data than that.

>Punctuated-equilibrium theory almost guarantees that some
>descendants of a common ancestor will often be largely unchanged (very
>little punctuation) compared to other descendants (with large amounts of

Punctuated equilibrium is the result of peripatric speciation (what you
have referred to as "paraphyletic speciation", iirc). Although the human
lineage may have arisen as a peripheral isolate, so might the chimp
lineage. It's difficult to study a speciation event that occurred several
million years ago--it involves multiple inferences based in part on those
same autapomorphies, and also a clear understanding of the phylogeny.

>     I am really tired of the erroneous belief of many strict cladists that
>all descendants of a common ancestor are equally "related" just because they
>are separated by an equal length of time.

So you are saying that my sister might be more closely related to me than I
am to her?

>P.S.  It's really not qualitatively different from the Theory of Relativity
>in Physics.

I'll leave this one to the physicists.

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