X-Message-Number: 4536
Date: 22 Jun 95 15:58:18 EDT
From: "Steven B. Harris" <>
Subject: CRYONICS: Metabolic Champs

Peter Merel says:
 
   >>Actually, as hunters, humans are considerably better adapted
than dogs and wolves. We have much better stamina than any other
animal - healthy humans can happily dog-trot better than thirty
miles a day, every day. This is mainly due to humans being the
sweatiest animals; if you ever need to hunt your dinner, you can
just trot after it until it drops of heat prostration. You can do
this even if you have a taste for dogmeat!<<

   Comment: I'd have to see this to believe it.  My feeling is
that if you want to live on dogmeat you have "run down," that in
any kind of normal climate you'd better target only fat arthritic
chihuahuas.  And even then you might well starve.

   It is a well-known fact among comparative physiologists (see
Schmidt-Nielsen's book _Scaling_, for instance) that canids are
the champs when it comes to the oxidative stamina department,
able to reach 30 times basal metabolic rate at VO2 max, when
other animals, and even the best trained humans (such as 
world-class cross country skiers), cannot go much above a factor
or 15.  Thus, a human may be able to dogtrot 30 miles a day, but
in the Iditerod Alaskan races, the best dog teams do 100 miles a
day for many days, and they do it ** pulling sleds **.  Humans
are good, but compared to dogs we are definitely second rate.

   The claim that humans can compensate for this relative
metabolic/cardiovascular disadvantage by superior heat loss
mechanisms, I suppose would have to depend on climate.  Obviously
nobody is going to run down huskies in Alaska, or for that
matter, wolves in Montana.  Perhaps you could run down a 
heat-stroked husky on the Serengeti, but that would a bit silly. 
The interesting evolutionary question is whether in a semi-arid
hot climate such as found in East Africa, a well-trained man
could run down canids adapted for such a climate, such as the
hyenas or the short-haired wild dogs.  Frankly, as I say, I do
not believe it, but I'm willing to listen if you've got stories.

                                      Steve Harris


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