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Bipedalism and other fact
J. Moore (j#d#.moore@canrem.com)
Sun, 25 Jun 95 11:57:00 -0500
JM> -Odd that you manage to suggest that, despite the fact that chimpanzees
JM> -manage to deal reasonably well with their potential predators, such as
JM> -lions and leopards, early hominids of similar size and brainpower would
JM> -be incapable of doing so.
Si> Well, I think chimps have a better opportunity to climb trees in the
Si> wooded environment which they live. I think that if early hominids were
Si> out on the open savanna, as the savanna theory states, they would have
Si> much less of a chance to escape from a predator, especially a lion, to a
Si> tree.
Sorta seems that way, doesn't it, as long as you don't take into account
how we are likely to have reacted to predators like the big cats. But
in fact (there's that word you hate so much, "fact":) what we see when
we look at predation on chimpanzees, those animals so similar in size
and intelligence to our early ancestors, is that they have more severe
problems (ie. they get killed) with leopards in more heavily forested
areas. In more open wooded savannah they show little concern with
leopards. Perhaps Adrian Kortlandt's experiments during the 1960s would
give us a clue as to why this is:
During the 1960s Dr. Kortlandt, a Dutch researcher, did a number of
experiments with wild chimpanzees in natural populations in Africa. One
of these was to see how different populations of chimps react to
predators. To do this, he used a stuffed leopard dummy with electrically
moveable head and tail. A baby chimpanzee doll was placed in the
leopard's front paws and the dummy was placed where it would be
encountered by mixed groups of chimpanzees, including females with young,
in all the experiments. Several populations of chimpanzees were so
tested several times, including groups in two different jungle areas,
and a group of savannah woodland chimpanzees. All the chimp groups
reacted by picking up sticks as clubs, breaking small trees and tree
limbs to use as clubs, and throwing these at the leopard dummy. An
interesting difference emerged between the jungle chimps and the
savannah chimps. The jungle chimps, while aggressive toward the
leopard, were uncoordinated in their attacks and when throwing objects,
never actually hit the leopard.
Dr. Kortlandt observed:
"The results with savannah chimpanzees, however, were quite different.
They grabbed the largest of the available clubs, which was 2.10 m long,
and they tore down small trees of about the same length; they slashed
viciously at the leopard with these. With the aid of the film we made,
we could measure impact velocities of approximately 90 km/h, which would
have been sufficient to break the back of a live leopard. In addition,
there was teamwork in evidence during these attacks, again in contrast
to what we observed in the jungle chimpanzees. During the final attack
the dummy was encircled by five chimpanzees, while two others stood in
readiness at some distance, in case they should be needed. Then the
leader grabbed the tail of the leopard and ran away, tossing the
predator so that the head flew from the body.
"With that, the enemy was considered 'dead'. The apes showed no more
fear of it, and the youngsters were allowed to touch it. The attacks on
its head, however, continued during the whole day.
"A side effect of the experiment was the observation that the savannah
chimpanzees more often walked erect than do the jungle chimpanzees."
Perhaps this difference is the result of being able to see your
potential predators, an great advantage over having them sneak up on you
unawares.
JM> All that matters is whether or not they do *well enough*; that's how
JM> evolution works. We see that in fact australopithecines did well
JM> enough
JM> to survive in their environment for millions and millions of years.
JM> And in fact even chimpanzees do well enough in relatively dry areas,
JM> similar to those used by australopithecines.
Si> The point is, however, if hominids were evolving on the savanna for the
Si> millions of years that they were supposedly, how come their evolution
Si> didn't bring them up to the level of other savanna creatures. It is
Si> that simple. I mean, don't you find it the least bit odd that the human
Si> body temperature of 98 degrees is more like that of a dolphin or a whale
Si> than that of other savanna creatures?
You mean, am I surprised that our body temperature is very like that of
our close relatives amongst the primates? No, actually I'm not, and I
would be surprised that you are except that I would imagine you have
done as much research on the subject as you usually do.:-(
NOTE: Humans have normal body temperature of between 36.7 and 37.2
degrees C (98-99 degrees F). Info from *Black's Medical Encyclopedia*
1987 *The Care and Management of Laboratory Animals*
Trevor Poole, ed. Longman Scientific and Technical: Harlow, Essex.
*Macaca mulatta* 36-40 degrees C
*Macaca fascicularis* 37-40 degrees C
*Papio hamadryas* 36-39 degrees C
________________________
1991 *Environmental and Metabolic Animal Physiology* 4th edition.
C. Ladd Prosser, ed. Wiley-Liss: New York.
pg. 111 (from Table 1):
Man 37 degrees C
Baboon 38.1 degrees C
Mountain sheep 37.9 degrees C night
Mountain sheep 39.8 degrees C
Goat 37-40 degrees C
Fur seal 38 degrees C
Humpback whale 36 degrees C
Bat (*Dobsonia*) 37 degrees C
_______________________
Did you know that our body temp is similar to that of some bats?
This isn't as much of a shock as you might think, since actually
mammalian body temperatures, except for monotremes and some marsupials
and a few other "primitive" mammals, cluster around a fairly tight range,
from about 34-40 degrees C.
About those whales, the ones you say have a body temp so similar to
ours. You didn't happen to do any *research* on those, did you? (I
think we all know the answer.) Let me help:
pg. 301 (after giving the body temperatures from many studies of whales):
"For the time being, at least, we may take it that the average body
temperature of Cetaceans in general is about 95.9 degrees F. -- a very
low figure indeed for a mammal.
"This figure is 2.5 degrees F. below that of man, whose temperature is
low in turn when compared with that of horse (100.4 degrees F.), of
cows and guinea-pigs (101.3 degrees F.), of rabbits, sheep and cats
(102.2 degrees F.), and of goats (103.1 degrees F.). Only hedgehogs
are known to have an average summer temperature equal to that of
cetaceans, while sloths, opposums, and duck-bills (89.6 degrees F.-93.2
degrees F.) are even more cold-blooded. But then the last-named species
occupy such a special position among mammals in so many respects, that
we may say that compared with terrestrial mammals, whales have a very
low temperature. Seals and related species certainly have higher
temperatures, for Clarke has measured 98 degrees F. in an elephant seal.
The hippopotamus, on the other hand, has a temperature similar to
cetaceans (96 degrees F.), and sea-cows probably have a lower
temperature still."
1979 *Whales* by Dr. Everhard J. Slijper (Professor, Zoological
Laboratory, University of Amsterdam). Hutchinson of London: London.
Seems that whales' body temps aren't as similar to humans as you said.
Big surprise all around, I'm sure. (And how 'bout that hippo?)
Si> And don't you find it odd that we
Si> expend a tremendous amount of energy and resouces to keep our body
Si> temperature constant, again like aquatic creatures, instead of allowing
Si> our internal body temperature to rise? Again, if we were on the savanna
Si> for the millions of years as you say, and did not have an interviening
Si> period of "aquatic-ness", instead evolving with the other savanna
Si> creatures, why then did we not end up evolving the same way?
Let me return that with another question: sea gulls and many other sea
birds excrete salt through nasal glands; crocodiles do so through salt
glands on their tongues (although it should be noted that some
scientists believe that these glands were developed to counteract the
effects of dehydration, a problem which crocodile, paradoxically, are
susceptible to). Why don't they both use the same method? Why
don't whales do it the same way; instead they have unusually large
kidneys. (Small whales have kidneys twice as large as those of land
animals of the same size.) And, in a related question, why do you
insist that all savannah animals deal with heat in the same way, when in
fact they utilize a variety of approaches to this problem?
The answer is the essense of evolutionary theory: relatedness. You
can't just "pick and choose" from the Big Book O' Adaptations; I'll have
one of those, and, oh, that looks good! just doesn't work in the real
physical world. You have to start with what you have, and consequently,
we shouldn't be surprised to find that we resemble primates in our body
temperature and thermoregulatory needs. We've been separated from other
animals for tens of millions of years, and just because they can let
their temperatures rise by 10 degrees on a hot day doesn't mean we can
forsake our primate heritage just because it seems like a handy thing to
be able to do.
Si> You point of "well they were there, on the savanna, and they mananged to
Si> survive well enough to get us to were we are today"; I don't think is a
Si> very good one. Sure we were there, but we ended up taking a different
Si> evolutionary path from the majority of animals there, now the question
Si> is why?
There aren't primates, for one, and more specifically, they aren't apes.
We've been separated from even baboons for probably about 20-25 million
years. We are far more closely related to apes, and especially to
African apes, than to anything else on the planet. That we resemble
them and not antelope cattle, aardvarks, and warthogs is not something
to be *wondered at*; it is to be *expected*.
Si> And then look for a SIMPLE explaination to cover all aspects of our
Si> unusual physical structures?
The "aquatic ape" is not "a simple explanation"; as only one problem,
how did we deal with our predators in the aquatic environment?
Jim Moore (j#d#.moore@canrem.com)
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