Re: Taung and AAH
Pat Dooley (patdooley@aol.com)
13 Dec 1994 23:55:31 -0500
In article <055jkms.2@chiron.wits.ac.za>, 055jkms@chiron.wits.ac.za
(JEFFREY K McKEE) writes:
>I am really baffled to read all this stuff about the Aquatic Ape
>Hypothesis. Someone noted that it is anthropologists who oppose the
idea,
>and perhaps that is because we anthropologists, particularly paleo-
>anthropologists, have the evidence.
<< deletions>>
>So when, and WHERE, did our ancestors go through this alleged aquatic
>phase? And why does ALL of the evidence contradict the AAH? Why is it
even
>worth discussing?
The period of interest that the AAT focusses on is from around 12mya to
around 4 mya. As you know, there ain't much fossil evidence from that
period that relates
to human ancestry. Like zip, nado, zero, none. Very convenient, you might
say.
But how did evolution get from the common human/chimpanzee/bononbo
ancestor to Lucy? Why was Lucy bipedal? Why were her feet so large
relative to her leg length? Bipedalism is a MAJOR evolutionary change.
To get an idea of how large, consider the fact that horses are more
closely related to one zebra species than that zebra species is to a
second zebra species; yet all three are more distantly related than
humans are to chimpanzees.
If we look at modern humans we see a number of features that are
way out of kilter - lots of fat, about 10x more than any other ape.
Hairlessness over most of the body. An eccrine/acropine ratio
of 99:1 compared to 52:48 in African apes. A diving reflex. Babies
that can swim before they can walk.
If we look at convergent evolution we see that most of the anomolous
features have evolved in aquatic/semi-aquatic or wallowing mammals.
NONE of them have EVER evolved amongst other primates or
amongst savannah animals (except the mole rat but that lives
underground).
The AAT theory merely proposes that a group of apes became
adapted to foraging on the shores of the extinct Sea of Afar, or
thereabouts, as their terrestrial environment dried out and got
as far as becoming reasonable swimmers and quite good
divers before taking an evolutionary U-turn back to a terrestrial
existence. They never became as aquatic as seals, as some
AAH opponents would have you believe, and it is likely they
spent much of their time on land. Why the reversal? The sea of Afar
dried up, much as the Dead Sea is currently doing.
Shouldn't you guys know all about comparative mammalian
anatomy, the principle of convergent evolution, and stuff
like that?
Want to try a little test? Next time you are out on the
savannah in the midday sun, strip off your clothes and
go chase some largish prey. That's what some posters
claimed our ancestors used to do and that that life-style
accounts for hairlessness, eccrine sweating, bipedalism
and so on. Second test. Go to an unspoiled beach,
strip off your clothes and go chase some crabs and shellfish.
If you're like most human beings you'll do rather better
at the second test, even if you have to wade out into
the water a bit.
Pat Dooley
PS Try reading Morgan's "The Scars of Evolution".
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