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more on aquatic elephants
Alex Duncan (aduncan@mail.utexas.edu)
6 Nov 1995 13:40:56 GMT
In article <47incs$e4d@scotsman.ed.ac.uk> , jamesb@hgu.mrc.ac.uk writes:
>>4) Since elephants have the features noted above, they must have aquatic
>>ancestors.
>>
>>5) Since humans share these features with elephants, we must have
>>aquatic ancestors.
>>
>>Can you say "tautology"?
>
>You are missing out the fact that many example of aquatic animals that
>are hairless, have subcutaneous fat etc. exist. If we only had elephants
>and humans to look at the argument would be tautological. I'm not saying
>the argument constitutes proof either, but I think postulating an aquatic
>phase in the ancestry for both elephants and humans explains these
>features. Have you got better explanation?
Yes, there are aquatic mammals that are hairless and have subcutaneous
fat. There are also aquatic mammals that have lots of hair, and no
subcutaneous fat. There are terrestrial mammals that are hairless.
EVERY terrestrial mammal that I'm aware of has subcutaneous fat. I don't
need to explain its presence in humans, because it's presence in other
mammals (esp. other primates) provides all the explanation I need for
this particular case: humans have subcutaneous fat because we are
primates (mammals, even) and primates have subcutaneous fat. Humans have
a lot of subcutaneous fat because we eat a lot. You'll see the same
thing in a lot of mammals in zoos, especially the carnivores, orangutans
and gorillas.
As far as hairlessness goes, it may be an adaptation to being a large
bodied diurnal primate. It has been demonstrated that if you are large
and bipedal, and spend a lot of time in the sun, then the combined
features of being hairless and sweaty will help keep you cool.
To get back to the elephant thing -- the AAT position on elephants is
that they have aquatic ancestors. Why? Because the features that
elephants and humans have in common can then be used to argue that humans
also have aquatic ancestors (after all, if humans have these features
because we evolved in an aquatic environment, then that must be why
elephants have them). The problem is that you're assuming what you're
trying to prove. It is tautalogical, and the very lamest excuse for
logic.
I repeat -- there is no evidence that elephants have aquatic ancestors,
and lots of evidence that elephants have terrestrial ancestors. The fact
that elephants have subcutaneous fat is meaningless, since virtually all
mammals share this feature. The fact that elephants are hairless is not
supportive of AAT arguments, as modern elephants are very large, rotund,
tropical animals, and like most very large, rotund, tropical animals
(e.g. rhino) are hairless. In addition, we have adundant evidence that
non-tropical elephants (e.g. mammoth) were not hairless. The fact that
elephants "cry" is evidence against the AAH, because elephants are
terrestrial. Or, if we really want to get particular, elephant "crying"
is meaningless to the argument, because the mechanism is different than
the one that we see in humans.
Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086
512-471-4206
aduncan@mail.utexas.edu
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