On Sep 25, 2005, at 6:57 AM, Leonard Matusik wrote:
Also in reality, most Trilobites were destroyed 250million years ago
in Permian extinction event (lotsa chances for
"MythicalRandomMutation" LOST there.)
ALL trilobites were killed off in the Cambrian extinction, about 500 MY
ago. The Permian die-off was about 250 MYA and mostly affected marine
species (about 95%):
<http://www.bbc.co.uk/education/darwin/exfiles/massintro.htm>
In the 250 million years between the end of the Cambrian era and the
end of the Permian, obviously a lot of changes were made. Fortunately
for vertebrates, one of the very few animals to survive the Cambrian
was a flatworm-like creature that had a notochord — precursor to the
spine. IIRC everything else that survived, multicellular-animalwise,
turned into arthropods or were colonial primitives like sponges.
So from the surviving trilobites (and whatever else made it) to the
first decent hominids is about 245 millions! (or 5% of the total age
of the earth)
Again, there were no surviving trilobites. They didn't make it out of
the Cambrian. From that time to now, half a billion years, we're
looking at about 1/9 Earth's age:
<http://www.talkorigins.org/faqs/faq-age-of-earth.html>
This raises the question of why it was that life seemed to sit and do
nothing for a very long time — nearly 3 billion years — before
exploding into the pre-Cambrian diversity that it held. Mats of algae
and stews of bacteria seemed to be all that was possible for quite a
long time indeed.
The secret ingredient appears to have been sex. Asexual reproduction,
in addition to being rather boring, doesn't introduce anywhere near the
possibility for diversification of a genome like sex does. So somewhere
around 700 to 1000 million years ago, life discovered this new way to
do things, and that seems to have been the real turning point.
But life's apparent diversity today is still not the whole picture;
proximally 95% of all species that ever existed are now extinct. Some
of that is due to mass die-offs, but a lot of it is also do, simply, to
evolution.
Eventually, in two populations isolated by geography (for instance),
one group of organisms simply cannot interbreed with the other, and so
you get a new species. Ring species are one rather interesting example
of this. If you go one way you have populations that can interbreed;
but if you go the other way, you have a disconnection:
<http://www.pbs.org/wgbh/evolution/library/05/2/l_052_05.html>
And if — when — one of the populations fails to survive, perhaps a
harsh winter or similar local catastrophe, you can argue that the
species is extinct, but there's still continuity there in the surviving
and altered branch.
Hence finding that the majority of species which used to be here are
gone isn't really that surprising, though some interpret it as a
warning rather than recognizing it as simple change. After all, Pangaea
is no longer on the maps either, yet no one mourns its passing.
Homo sapiens as we know it today is doomed, like 90%+ of all
other terrestrial species, to extinction.
hmmmm, perhaps... Or maybe HomoSapients-Universalis will be able to
interbreed with all species..... I've allways wondered about that
Polyploid Honey from "The Fifth Element"... What do you think she's
got hiding in those genes?
Everything. IIRC the doctor in that movie claimed that *all* her genes
were active, not 97% or so deactivated like the junk DNA humans have.
That's a cute but impossible idea, since you really wouldn't want most
of that stuff switched on. It might code for scales and gills, for
instance, fins instead of fingers, etc.
Junk DNA is why the "loss of information" argument from ID-iots is
specious. The information to, say, grow eyes — or segmented abdomens —
is not lost. It's still there; it's just switched off, but it can be
switched on again any time. It seems that once DNA "learns" how to do
something it doesn't forget; it simply stops doing it in favor of some
other variation that, for whatever reason, is more optimized to fit a
given environment.
Finally, it's easy to overlook the quiet mutations that don't have any
apparent effect at all on an organism's ability to succeed … *until*
some major change to the local scene takes place, and suddenly an
unimportant variation could well be the single difference between
survival to breed or vanishment.
Genetic change isn't always about producing something that's clearly
immediately superior (or inferior) to other members of the population.
It can often be about these kinds of minor and seemingly unimportant
variations which end up being crucial because of entirely stochastic
environmental effects.
One example would be the famous case of peppered moths living in
England, which appeared to have taken on a sooty color in response to
large levels of coal soot in the 1900s. IIRC it turned out that the
moths didn't change their color; the black shading was one variation,
which had been present long before the industrial revolution, that
ended up being more successful because of pollution than their more
lightly-colored counterparts:
<http://www.millerandlevine.com/km/evol/Moths/moths.html>
That is, the color differences had been there long before pollution;
they only became more successful *after* soot helped them hide more
effectively.
--
Warren Ockrassa, Publisher/Editor, nightwares Books
<http://books.nightwares.com/>
Current work in progress "The Seven-Year Mirror"
<http://books.nightwares.com/ockrassa/Flat_Out.pdf>
<http://books.nightwares.com/ockrassa/Storms_on_a_Flat_Placid_Sea.pdf>
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