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Re: Size and Extinction (fwd)
> That means that 99.9% of all life forms were "failures."
You make it sound so judgmental. Yes, all species evolve to a
point--at some point in space (geographic or morphologic or both) and
time they are going to run up against some sort of environmental stress
that they cannot cope with ( Elephant dentition enamel is a perfect
example). At that point they begin to fail, that is they become rare.
An organism going extinct is random. When the Calf. Condor goes out it
is going to be because some tech drops the last egg--it is random. The
issue is when did the condor become rare in the first place. Species
become rare because they do not experience the correct chance mutation in
the genotype to cause the correct phenotypic expression to enable them to
handle what the environment is dishing out. They fail.
> Dinosaurs disappeared BECAUSE they were adaptable. They radiated out
> gloriously becoming extreme specialists just as you advocate, but weren't
> generic enough to make it when the ol' exploding bolide from outer space
> paid them a call.
Let us have this conversation in ten years when there is some
sort of conclusive evidence that the boilide caused the extinction.
There simply hasn't been enough good work done on this issue to be able
to make these gross generalizations. It is speculative.
> Including such bolides from outer space in the category of "normal
> stresses of evolution" is analogous to saying that you won't buy a car
> because it's not structurally strong enough to withstand meteor impact.
> I think your day-to-day priorities, like the dinosaurs, are a bit
> different. I personally would not blame you if you opted for, say, fuel
> efficiency or boss woofers or great 0 to 60, and would think asteroid-car
> man was a bit odd. Wouldn't you?
Listen, nothing makes any sense if taken out of context.
Analogies and explanations only work if they are qualified by
establishing parameters beyond which they are not valid. If one of my
students leaves the university and fails to graduate, whether or not he/she
"went extinct" depends on why he/she left. If he/she left Penn because
he/she was hit by a car or got cancer, that is not extinction (but it is
analogous to the sun becomming a red giant) A student only "goes extinct"
if he/she "fails out" because of an academic reason. The Ivy League is a
tough place, there are high attrition rates-academic attrition rates. Of
course if an asteroid blew the planet into bits the species didn't fail.
We are talking about extinction here, not extraterrestrial genocide.
However, if a student doesn't survive calculus or physics they
either didn't work hard enough, they don't think the same way the system
forces them to, or they are not bright enough (ASSUMING NO EXTERNAL
INFLUENCES LIKE CANCER). Any of these three reasons is a lack of fitness
for the student to pass the course.
Taken even further (assuming this analogy can go this far), I
know friends from college who had 4.0 GPAs, walked into the best graduate
programs in the country and fell flat on their faces because they
couldn't synthesize--they were rote machines. They became extinct in the
academic game because the environment changed to a degree that they could
not adapt to. They "failed" to adapt and they went extinct.
And, extreme adaptation into tight, little boxes of the
ecological regime means that the organism is really good at what it
does. If, however, the thing cannot adapt to the changes that go on
around it, it is still a failure in the evolution game. Just because an
organism is really good at something (AT A GIVEN POINT IN SPACE/TIME)
does NOT mean that it is going to make it as long as the cockroach has.
Only the strong surviving is probably over simplifying things. Only the
strong and adaptable survive. In some cases only the strong and quickly
Yes, 99.9% of everything that has ever existed on this planet is
dead in a phylogenetic sense. Yes, that does mean that they failed to
adapt at some point. That allopatric speciation might have allowed the
phylogenetic lineage to occur is not the issue. The fact that birds are
still around and theropods are not is fine. But the simple fact that
birds are extant doesn't change the issue that the Theropoda sensu
stricto is not. The theropods failed. It doesn't mean that they were
failures in what they did--they weren't. It does mean that they failed
to adapt at a point and got selected out of the game. Nature doesn't
care how good you were in your past. If you are not cutting the mustard
now, you get fired without a pension. There is no tenure.
Department of Geology
University of Pennsylvania
356 Hayden Hall
240 South 33rd Street
Philadelphia, PA 19104-6316