human origins

John Grehan jgrehan at SCIENCEBUFF.ORG
Thu Jan 22 14:06:03 CST 2004


Some (possibly naive) responses to Richard:

At 10:57 AM 1/22/2004 -0600, Richard.Zander at MOBOT.ORG wrote:
>Well, hang on a minute there. The molecular data are commonly sufficient to
>allow statistical tests of reliability but morphological data are generally
>not. It isn't just "genetic sequence similarity" to the exclusion of
>morphological data.

The trouble occurs when one lot conflicts with the other to give two
totally different patterns of relationship (in this case human-chimpanzee
vs human-orangutan).

Something may be statistically 'reliable' while still actually being wrong
(i.e. all the stats in the world supporting the genetic similarity just
confirms the genetic similarity - whether or not this similarity
necessarily translates into a phylogenetic (spatiotemporal pattern of
differentiation) similarity would seem to be another question.

>Naturally, the presumption is that if random generation of parallel traits
>in closely related but not sister lineages is not to be expected by chance
>alone, one can assume shared ancestry of apparent sister taxa.

Its certainly an assumption.

>This is notexactly true since coadaptive traits associated with habitat
>may also force
>parallelism (pointed out by Landrum, Rensch and doubtless others) and thus
>confound at least details of a cladogram.

If one believes in natural selection as the driving force for taxogeny

orphology and exons are liable to this problem, I believe.

Whether or not one believes in this problem, the fact remains that
orangutans have all these very prominent 'human' characters (or is it the
other way around) including the very cognitive inclinations that underpin
human technological thinking.


>Statistcally impressive results from introns and junk DNA are hard to
>explain away.

Perhaps no harder than explaining all those morphological synapomorphies
between humans and orangutans in this case.

Cheers, John




>-----Original Message-----
>From: Ronaldo [mailto:ralperin at TERRA.COM.BR]
>Sent: Thursday, January 22, 2004 4:06 AM
>To: TAXACOM at LISTSERV.NHM.KU.EDU
>Subject: Re: [TAXACOM] human origins
>
>
>Hello John,
>
>Wednesday, January 21, 2004, 1:23:53 PM, you wrote:
>
>
>
>"So in conclusion the paper is fairly representative of what I am reading
>  in general. The chimpanzee relationship is presented as a fact. It is
>  based on the presumption of genetic sequence similarity being the whole
>  truth of phylogeny, and morphological considerations are rendered almost
>  a foot note with the consequent lack of rigor in any connection being
>  substantiated between living humans and other apes and purported fossil
>  representatives. "
>
>
>  Fully agreed! John, here in Brazil we have the same situation with
>  the primates in general. Just see the huge number of papers regarding
>  "Phylogenetic" relationships among Neotropical Primates. I have to
>  ask; "Phylogenetic" or Molecular (with no explicit criteria)
>  relationships?
>
>
>  Ronaldo Alperin
>
>JG> John Grehan
>
>JG> Dr. John Grehan
>JG> Director of Science and Collections
>JG> Buffalo Museum of Science
>JG> 1020 Humboldt Parkway
>JG> Buffalo, New York 14211-1293
>JG> Voice 716-896-5200 x372
>JG> Fax 716-897-6723
>JG> jgrehan at sciencebuff.org
>JG>
>http://www.sciencebuff.org/biogeography/Panbiogeography/Panbiogeography-Gate
>.htm
>JG> http://www.sciencebuff.org/HepialidaeGate.htm
>
>
>
>
>
>--
>Best regards,
>  Ronaldo                            mailto:ralperin at terra.com.br

Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, New York 14211-1293
Voice 716-896-5200 x372
Fax 716-897-6723
jgrehan at sciencebuff.org
http://www.sciencebuff.org/biogeography/Panbiogeography/Panbiogeography-Gate.htm
http://www.sciencebuff.org/HepialidaeGate.htm




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