Paul Neubauer
Oct-28-93 01:48PM
The Aquatic Ape - news

Organization: Ball State U.
From: 00prneubauer@leo.bsuvc.bsu.edu (Paul Neubauer)
Message-ID: <1993Oct28.164813.24116@bsu-ucs>
Followup-To: talk.origins
Newsgroups: talk.origins,sci.bio,sci.skeptic

In article <2043@rand.mel.cocam.oz.au>, pjd@cocamrd.mel.cocam.oz.au
 (Pat Dooley) writes:
> The geological history of NE Africa provides a locale for the
> evolution of the AAT. There are no fossils from the period during
> which the aquatic phase occurred, but the fossils of the descendents
> of the AA have been found close to lakes and in a distribution that
> suggests radiation from the NE African locale down the Rift valley.
> The Baboon marker gene, or rather its absence in Homo sapiens and
> non-African primates, supports the idea of a period of evolution
> occurring outside of mainland Africa.

I followed up on an earlier reference to the baboon marker gene, but
(possibly because my site does not regard either alt.books.review or
sci.anthropology (!?) to be valid groups) I posted (I presume
successfully) only to talk.origins.  Apparently Pat Dooley is
following this discussion from some other group and no one else seems
to have seen fit to respond.  (I don't even know if the posting got
out.)  Anyway, I will have at it again and will mail a copy of this
posting to Pat Dooley.

Our university library does not have _Scars of Evolution_ so I am not
able to consult it readily.  However, the baboon marker gene argument
strikes me as quite incomprehensible.  A number of people who I have
some reason to believe to be both smart and sane seem to be supporting
or at least for the sake of debate taking a position of support for
the AAT.  Perhaps someone will see fit to correct me if I am
misunderstanding the point of the baboon marker gene argument.

It is generally believed that genes are passed from parent to child,
and more generally from ancestor to descendant.  If this belief turns
out to be incorrect, then we have much bigger problems than the debate
concerning the AAT vs. the savannah theory.  (;-)  On the other hand,
if we retain the standard assumption about genes, then either the
baboon marker gene argument is irrelevant or other major assumptions
about the relatedness of humans to other primate species will have to
be overturned in a radical way.  Consider the following (sketchy, but
otherwise relatively standard) cladogram:

     primates
    /        \
...           old-world monkeys
              /               \
          monkeys              apes
         /   |   \            /    \
     ...  baboons ...   orangutan   *
                                   / \
                            Gorilla   *
                                     / \
                                   Pan  Homo
                                   / \
                              chimp   bonobo

This cladogram certainly supresses a number of nodes, but strikes me
as being reasonably standard insofar as it represents the relationship
of the members shown.  Under the assumption that this cladogram has
any relation to reality, a gene shared by "all African primates" would
have to have been introduced at least as early as the node labeled
"old-world monkeys" and then the gene would have to have been lost
(independently) in Pongo (the orang) and Homo, but retained in the
lineages (other than Homo) that inhabit Africa.

If the above cladogram is correct, then (pace other weird and ad hoc
assumptions about genetics) it must be regarded as simply a
coincidence that neither orangs nor humans possess the baboon marker
gene while baboons and chimps do.  A gene is not like a the family
photo album.  There is no known mechanism that would cause a gene to
be lost simply by virtue of its posessor moving, the way moving to a
new house can cause one to lose one's more alienable belongings  :-(.

If there is any force to the baboon marker gene argument, then, it
must come from the assumption of a cladogram more like the following:

     primates
    /        \
...           old-world monkeys
             /                 \
           African              Non-African
          /       \             /        \
     monkeys       apes      monkeys     apes
    /   |           /  \                 /  \
...  baboons   Gorilla  Pan          Pongo   Homo
                        / \
                   chimp  bonobo


(Many others omitted, obviously.)  For this to be true would require
more than just a reevaluation of the human lineage during a period
variously estimated as from 3-12 My ago, but a rather severe shakeup
of the entire "tree" of primate evolution.  Frankly, I see an argument
that depends on (as opposed to arguing for) such a serious upheaval in
standard theories to be one of the primary indicators of a crackpot.
(Does this remind anyone of Velikovsky?)

Since, as I noted, there are a number of people who I have reason to
believe not to be crackpots (e.g., Bill Calvin, Herb Huston, Paul
Keck, and others) who seem to be supporting or at least not dismissing
the AAT, I have to wonder if it is I who has missed the boat.  I don't
see how my analysis could be that far off, but neither have I seen the
details of the baboon marker gene argument.  What could Morgan have
been thinking of that would have caused the human lineage to have lost
the baboon marker gene simply by virtue of having been isolated from
the African mainland?  In the absence of such a factor (mechanism
please) how can the argument be taken seriously?

If I am misguided, please enlighten me.

--
Paul Neubauer   00prneubauer@leo.bsuvc.bsu.edu  00prneubauer@bsuvax1.BITNET
                00prneubauer@bsu-ucs.UUCP       neubauer@bsu-cs.UUCP