Re: Lizard engines and rat engines


"r norman" <rsn_@xxxxxxxxxxxx> wrote in message news:damprs$1f2n$1@xxxxxxxxxxxxxxxxxxxxxx
> On Fri, 8 Jul 2005 08:21:36 -0400 (EDT), "g" <gillawton@xxxxxxxxxxxxx>
> wrote:
>
> >
> >"dkomo" <dkomo871@xxxxxxxxxxx> wrote in message
> >news:dak4st$eco$1@xxxxxxxxxxxxxxxxxxxxxx
> >>g wrote:
> >>
> >
> >>
> >> And it jars me to see someone make a statement like this, which to me is
> >> akin to ignorance. Elephants have big ears for very *specific* reasons.
> >
> >???
> >> Being so large and living under the blistering sun of the African
> >> savannah, African elephants have severe problems with potential
> >> overheating. Their ears are an important way of dissipating much of
> >> this body heat.
> >>
> >Let me see if I'm getting this right. If the why of it is that larger
> >animals
> >have big ears because of their size and the temperature of the climate
> >where they live, then giraffes and ostriches have ears that are not as large
> >because they are smaller and live in a cooler climate. And Indian elephants
> >are smaller and live in a cooler climate, which explains why theirs are
> >much smaller. And jackals have larger ears for their body size than
> >rinoceroses because they are larger than rinos and live in a hotter climate.
> >
> >Now that's ...
> >
> >Uh oh, wait...
> >
> >No that's not right...
> >
> >Dang ! For a minute there I almost thought I got it.
> >
>
> There is an extensive discussion of this same topic over in
> talk.origins, including a rather long post by me about the
> comparative and environmental physiology of temperature regulation.
> There are a number of advantages and disadvantages to homeothermy
> (maintaining a constant body temperature). As is always the case in
> biology, there are animals that "choose" one strategy and animals that
> choose another. Furthermore, there are many physiological tricks
> animals can use to maintain regulate their body temperature. Large
> animals tend to have a problem with overheating, the larger the animal
> the worse the problem. Large "chunky" animals have a much worse
> problem than animals with long, thin elongated body regions,
> especially if those regions are not covered in thick, heavy skin and
> fur or feathers. Having large ears is just one trick to cool off.
> Few organisms use that technique, elephants and rabbits being the two
> most common examples. Other organisms have different tricks.
>
> Note: True, rabbits are not particularly large. Nevertheless, they
> found that trick to be useful. Evolutionary tricks, like all weird
> adaptations, are sporadic in distribution demonstrating independent
> evolutionary origin.
>

There is actually a fairly important philosophical/epistemological
point buried in this spat.

Gil is quite correct that, for some WHY questions with an answer of
the form "B because of A", it is important to check that you get B
whenever you have A.

An example might be the answer to the question "Why does the Earth
have a (strong) magnetic field?". If the elements of the answer
do not also serve to explain why Venus does not have a strong field,
then the answer is suspect.

Dkomo is quite correct that, for some WHY questions with an answer
of the form "B because of A", it is not necessary to perform the
cross-check. For answers to these kinds of questions, it may be
quite acceptable to say "B because of A in this case, but something
else because of A in another case."

An example is the one given - African elephants have large ears to
dissipate heat. And other beasts have evolved other ways to dissipate
heat. And some beasts (bats) have large ears for reasons having nothing
to do with heat.

ISTM that the difference between these two situations is that a different
kind of explanation is being given - that is, a different kind of "WHY"
is involved. In Aristotle's terms, we are giving a "material cause" and
"efficient cause" explanation of magnetic fields. But we are giving a
"final cause" explanation of elephant ears.

To my mind, this toleration of final cause explanations in biology is
exactly the thing that separates biology from the physical sciences.
Teleology simply cannot be expunged from biology. If we attempt to do
so, we impoverish the science.


.

Relevant Pages

  • Re: Rabbit ears
    ... selection since in every species of animals with ears, ... Can we find tiny mammals with relatively large ears? ... elephants have much larger pinnae than Indian ...
    (talk.origins)
  • Re: Rabbit ears
    ... insufficient as an explanation because the majority of animals do not have ... What gives you the idea that the have big ears? ...
    (talk.origins)
  • Ringling Bros. Battles to Keep Elephants
    ... People should boycott the circus. ... the Asian elephants used in the Ringling Bros. ... the American Society for the Prevention of Cruelty to Animals and the Animal ...
    (alt.true-crime)
  • Re: Lizard engines and rat engines
    ... >> Being so large and living under the blistering sun of the African ... African elephants have severe problems with potential ... > have big ears because of their size and the temperature of the climate ... > because they are smaller and live in a cooler climate. ...
    (sci.bio.evolution)
  • Re: What are you sitting at?
    ... Should we call them elephants? ... So if I look at a cow in a field, and admire the beauty of the animal, ... if you take a car to pieces and then reassemble the same ... live animals are Anglo-Saxon. ...
    (talk.origins)