Re: Lizard engines and rat engines
- From: "g" <gillawton@xxxxxxxxxxxxx>
- Date: Thu, 7 Jul 2005 08:46:36 -0400 (EDT)
"dkomo" <dkomo871@xxxxxxxxxxx> wrote in message
news:daghdr$23qu$1@xxxxxxxxxxxxxxxxxxxxxx
> Everybody knows reptiles are cold blooded and mammals are warm blooded,
> but not too many people are aware just how exorbitant are the energy
> demands of the heat engines that are the bodies of mammals.
>
> Typically, mammals require ten times the energy to run their bodies at
> their rated 37 degrees C (98.6 degrees F) as reptiles do, using basal
> metabolic rate as a comparison.
>
> Chris Lavers in his _Why Elephants Have Big Ears_ provides an
> interesting illustration of this difference. Imagine a lizard and a
> rat of the same size sitting under a tree. If the lizard's body engine
> is idling at, say, 100 RPM, the rat's will be running at 1000 RPM.
> Engine speed equates to the rate of heat-producing metabolic reactions
> within cells.
>
> But when the engines are pushed, the rat gets much better performance.
> If they both decide to run to another tree a kilometer away, the lizard
> wll rev his engine to 1000 RPM, but the rat will push his to 10,000 RPM.
> If the outside temperature is 38 degrees C to give the lizard a fair
> chance (the lizard's body will be at the same temperature as the
> surroundings, and its musclar efficiency improves as temperature rises),
> the rat will cover the distance at about 88 meters per minute, while the
> lizard will manage only 13 meters per minute.
>
> However, if the two animals were cars and the lizard got, say, 30 miles
> to the gallon, the rat would only get 3 miles to the gallon.
>
> Given the severe energy demands of warm blooded animals, it is a wonder
> that mammals and birds (who are also warm blooded) ever evolved from
> their last common ancestor, which was a cold blooded reptile of some
> kind. And this full-blown warm bloodedness must have developed
> independently in the evolutionary lines leading to each.
>
>
> --dkomo@xxxxxxxx
>
dkomo,
Please allow me to pay due respect to currently conventional terminology
which, despite connotations and denotations, is understood clearly, I am
told, by educators and professionals in fields relating to biology and
biological evolution.
It is not my intent to challenge conventions or covenants among leaders in
the field here. I would like to comment on something, however, about the
logical dissonance, as it were, that vibrates in my mind when I hear any
question about bio-evolution that begins with the word, "Why...?"
In my way of thinking (right, wrong or otherwise...) the answer to EVERY
such question would be:
"Because that was a statistical possibility within reach of the evolving
players,
and which they got around to at a time and place within which it worked and,
therefore, became a fixture."
The reason I chose the word "players" rather than "species" is that it also
makes me uncomfortable to call something a species when it is undergoing
changes over thousands or tens or hundreds of thousands of years, and even
branching into more than one species, given enough time. I suspect even the
word "players" is only a poor substitution.
But, again..., I do not mean to undermine any good words here, nor judge
anybody for using them provided the user knows precisely what he means by
them and his audience person does, too.
"Because that was a statistical possibility within reach of the evolving
players,
and which they got around to at a time and place within which it worked and,
therefore, became a fixture."
The word "fixture" I picked to indicate that something can get established
in
a player and remain after its usefulness is expired.
At the rate elephants are diminishing in the wild, I have a pained feeling
there
won't be any around in another hundred years if they last even that long.
Right
now, unfortunately, their tusks are a liability (due to illegal
opportunistic
hunting and the black market demand for them). And I don't foresee that
they
will be able to de-evolve them any time soon simply because it would be to
their advantage to stop growing them.
If evolution revolved around "why" things should happen, elephants would
have a "why" in that those of them who have tusks are getting taken out of
the
gene pool at a time when their numbers (male and female) already are moving
toward a danger of too much inbreeding.
Of course after they are gone I, too, shall be gone, too. But if I should
still
be around then, and somebody were to ask me "Why did elephants disappear
from the earth?" I would answer, "Because they had evolved characteristics
which -- although they passed the ecology's situational features for many
thousands of years -- were to fixed to be de-evolved fast enough to pass the
changed ecological tests of the twentieth and twenty-first centuries. It
wasn't
just their tusks. It wasn't just their large size. It wasn't their need
for enough
territory to allow food to regrow, rather than be trampled down on too
limited
a range... because man needed more and more of that range for farming. It
was
those things and more... that had become relatively fixed (meaning too well
established to get mutated out as quickly as was demanded by the rapid
changes
in their milieu.
If they could have done enough mutations fast enough, they could have
reduced
their size to that of a pot-bellied pig and might have made good pets for a
few
more years until suburban sprawl, with increasingly stringent conventions
and
covenants (of another kind than biological terminology) made even that
evolutionary form a liability.
Conventions and codefendants are necessary. They sometimes make life hard
for elephants, and clarity and creative ideas that don't conform to them.
(:>)
g
.
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