Aquatic Ape: The Fossils Say No!

NICHOLLS PHILIP A (pn8886@thor.albany.edu)
Sun, 1 May 94 04:24:13 GMT

> Lucie Melahn (lmm5@cornell.edu)

> People are getting into very heated battles over the evidence for
> and against aquatic v. savannah apes. There is no point to this.

We know that at some time hominids ventured out onto the savannah.
We know that because that is where we find the earliest hominid
fossils. Morgan did not argue this point. What she maintained was
that the "aquatic phase" occurred prior to the appearance of A.
afarensis and that aquatic life pre-adapted hominids to the savannah.
Now since everyone admits the savannah was involved the issue is not
aquatic vs savannah ape (or protohominid) but whether there is
evidence for an aquatic phase.

Morgan discusses a long list of physiological differences between
apes and humans which she claims are "scars" of our aquatic
ancestry. David listed many of these in a previous post. The major
problem with this list is that there is really no reason to believe
that all of those traits occurred at the same time (the 1 million
year aquatic phase). To put it into conventional evolutionary
theory, Morgan assumes that these traits became fixed in the human
phenotype as a result of an adaptation to aquatic life. Some of
them, she claims, are the result of convergent evolution while others
are unique adaptations (like bipedalism) that carried over into
savannah life. In my opinion, Morgan has not made a convincing case
for either convergence or an aquatic origin of bipedalism.

Many of the traits are inconsistant with aquatic life. This includes
hair loss and sweat glands. Some can be explained as the result of
phylogenetic trends unrelated to early hominid evolution. This
includes the shape of the nose which, as I tried to point out, is the
result of the flat hominid face. As for bipedalism, it is important
to consider the fact that apes do not as a rule spend much time in
water and even if they did there is no evidence that water would act
to promote bipedalism. The re-orientation of the pelvis and the
changes in muscle distribution reflect weight-bearing. A aquatic ape
would have most of its weight supported by water. That is why
aquatic mammals tend to have thin pelvic bones.

Now we know that primates do walk bipedally from time to time. Some
are so well adapted to trees that when they are on the ground they
cannot walk quadrupedally. Most of the hypotheses I have seen are
based on known patterns of primate behavior or biomechanics.



-- 

Philip Nicholls                   "To ask a question,

Department of Anthropology         you must first know

SUNY Albany                        most of the answer."

pn8886@thor.albany.edu