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

[Curtis Clark]

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
>punctuation).

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.