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Aquatic canines and other holiday musings
JEFFREY K McKEE (055jkms@chiron.wits.ac.za)
Fri, 16 Dec 1994 08:04:21 GMT
I do not wish to get sucked into the debate about the Aquatic Ape
Hypothesis, as I gather that it has become quite a protrated polemic and,
being new to this board, I do not know what has gone before. Nevertheless,
it is a holiday in South Africa today so I have some time to kill, and as
Pat Dooley has gone to the trouble to lay out some interesting notions,
based on Hardy and Morgan, I will take the bait ... once.
Dooley suggests that the hypothetical aquatic apes must have evolved during
the period 12-4 Myr, which is "conveniently" void of hominoid fossils. The
recent discovery of <Australopithecus ramidus>, IF it proves to be a
hominid, would seem to be a problem. It is dated to 4.4 Myr, is VERY chimp-
like, and was found in a forested environment, not by the sea. It is
interesting to note also that the South African site of Langebaanweg on the
Atlantic coast just north of Cape Town, dating to circa 5 Myr, has no
hominoid remains despite its wealth of fossil biodiversity (perhaps too far
south for the Aquatic Ape to swim? I don't know.).
Ok, so there is no fossil evidence FOR the Aquatic Ape, and negative
evidence is difficult to interpret. Lack of fossils does not mean that
something did not exist. So let's look at the logic of the AAH and see if
it has any merit.
Let's start with swimming babies. Many years ago I saw a video of Russians
tossing babies into a tank and watching their graceful movements. It was
hardly what I would call swimming. At that time, back in my youth, I was a
lifeguard at a swimming pool ... had I seen a child in the water doing what
the Russian babies were doing, I would have been compelled to jump in and
rescue the hapless individual before it drowned. When my first child is
born, due next June, I will not rush to toss it in the water. Here in
Johannesburg, drowning is one of the highest causes of infant mortality
(among affluent whites with backyard swimming pools). Some aquatic
adapation! As I noted before, although we cannot know how the Taung child
(type specimen of <A. africanus>) died, drowning is as likely an explanation
as any. We may have lost the putative aquatic adaptation quite quickly!
I notice that many dogs, especially labradors, are fine swimmers. Was there
an Aquatic Canine in their ancestry? Maybe that would explain why their fur
is so much like that of a seal or an otter.
True, some aquatic mammals have lost body hair, etc (although none of
them are bipedal, as far as I am aware). The AAH proponents would like us
to believe that these are good adaptations for swimming, but lousy
adaptations for savannah living. But here is my problem with such logic:
if loss of body hair, acquisition of eccrine sweat glands, etc., arose
before our ancestors moved into the savannah, and if it is such a poor
adaptation, why did it survive for at least 3 million years? We have good
fossil evidence that hominids exploited the savannah (and other environments
as well) across Africa for the past 3 Myr. That is a long time to live with
an inadequate adaptation ... certainly natural selection would have had
ample time to purge our bodies of this aquatic vestige and supplant it with
a more appropriate adapatation; there are still hairy people around today,
and if they would have had an advantage in the hot African sun then
selection would have done its thing rather efficiently. Alternatively, if
hairlessness etc. was an aquatic adaptation unsuited for inland pursuits,
and nothing better came along within our genetic capabilities, our ancestors
probably would have gone extinct and we would not be here to ponder our
origins.
Dooley suggests that I try a test of stripping off my clothes in the midday
sun and go running about the savannah (or something to that effect).
Believe me, I have tried to do that (as much as modesty would allow) and I
did not make it far. "Only maddogs and Englishmen go out in the midday
African sun". Most animals, in fact all mammals I can think of, rest at
midday and if possible get out of the sun; this is even true of the baboons
I watch at Taung, who are capable of going without water for something like
20 days. Even at other times of day, particularly in the summer time, it
can get bloody hot under the African sun. Part of my problem in pursuing
Mr. Dooleys suggestion is my white skin. The local people I work with at
Taung, however, have an amazing capacity to endure the heat and the sun,
largely due to the high melanin content of their skin. When they get hot
and bothered, and enounter water, they DRINK it, but don't usually swim in
it! And, like the white babies of the Johannesburg suburbs, the black
children of Taung occasionally succumb to a tragic death of drowning in
the few shallow pools that exist ... perhaps a vestige of the Taung child's
haplessness around water some 2.8 Myr ago.
Bipedal locomotion, eccrine sweat glands, etc, tend to serve human beings
well. Just ask a hunter-gatherer from the Kalahari desert. It is an
adaptation that works, and therefore survived the challenges of natural
selection for the past 3 Myr or more. You may be interested to read the
research of Chris Ruff (sorry, I don't have a reference handy at the moment)
who demonstrates the advatages of orthograde posture in maintaining a
reasonable body temperature.
Finally, it has been suggested that I read Morgan's "The Scars of
Evolution". I am reluctant to do so, for I bought and read "The Aquatic
Ape", and despite the fun I had reading it, I did not feel that Morgan was
worth shelling out any more money from my pocket. However, maybe some day.
Meanwhile, may I suggest that you (meaning anybody who has read this far)
read "The scars of evolution", written in 1951 by Wilton Krogman (Scientific
American, vol 185).
And now it is getting hot, so I am going to go for a swim.
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