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09/19/2000
Survivors
I watched the last Survivor show on TV and was intrigued by the
strategies that the four finalists used to enhance their chances of
winning the million dollars. Although I only saw the Survivor
finale, I couldn''t avoid the media telling me that rats were one of
the food items the contestants ate. Most, myself included, would
find that gourmet treat rather distasteful. However, an article in
the September National Geographic mentions a favorite food of
the Apatani tribe in northeastern India. It''s the Talle Valley rat,
described as a compact creature with thick brown fur. This
should go well with the tasty corn smut I mentioned a few weeks
ago! I was impressed by the fact that the author of this
Geographic article, Jesse Oak Taylor-Ide, was only 17.
Survivors of greater importance to all of us are the survivors of
several mass murders that took place a number of years ago.
One of these mass murders, better known as mass extinctions, is
the subject of an article by Hillel Hoffmann in the same National
Geographic. In any murder case, identification of the perpetrator
is a major goal. Our earth''s history is filled with mass
extinctions but paleontologists agree that at least five were, as
Ed Sullivan used to say, r-e-a-l-l-y big ones. In spite of much
sophisticated scientific detective work, the perpetrator has been
identified beyond a reasonable doubt in only one case. As we all
know, dinosaurs ruled the earth for millions and millions of years
when suddenly, in a poof, they were gone. This so-called K-T
extinction occurred a mere 65 million years ago. The murderer
was a bulky visitor from outer space - an asteroid, meteorite,
comet or whatever. The impact of that object on our fragile little
planet in the Yucatan Peninsula region of Mexico set off various
calamities such as climate changes and extensive wildfires. A
zone of incineration in North America resulting from a shock
wave containing white hot debris has been proposed.
While the K-T affair was indeed devastating, it pales in
comparison with the earlier "Permian extinction". The
perpetrator in the Permian case eludes conviction even to this
day, 250 million years later. There was lots of life on earth back
in those days. Most of the animals belonged to a group known as
synapsids, sort of mammal-like but mammals had not yet been
invented. King of the synapsids was the saber-toothed
gorgonopsid. These gorgons were pretty fearsome creatures with
teeth like a saber-toothed tiger and they enjoyed feasting on other
more peaceful plant-eating synapsids. In the reefs along the
coasts there was an abundance of marine life including fish,
corals and other sea creatures. Everything was going along
nicely when suddenly, something happened. (When I say
suddenly, you have to realize that this time ''suddenly", may mean
a few million years!) What happened was the Permian
extinction, during which about 95% of the sea species, 90% of
the plant species and about 70% of the land species were killed
off forever.
In his article, Hoffmann describes paleobiologist Cindy Looy
taking him to what she considered the best place to see what it
was like after the Permian extinction. The place is the Black
Triangle in the brown coal belt that overlaps parts of the Czech
Republic, Poland and Germany. After World War II, there was a
huge influx of mining and heavy industry in this region. The
result has been a kind of mass extinction due to the acid rain
spawned by the concentrated human activity. Surprisingly, from
a distance, the hilly terrain looks perfectly green and healthy. A
closer look reveals that, where there had been forests just a few
decades ago, there are now only stumps or fallen timber hidden
by the lush growth of acid-resistant weeds. No birds or insects.
Today, the European Community has joined with the three
involved nations to improve and monitor the air quality and to try
to undo the environmental damage in the Black Triangle.
Cindy Looy''s opinion is that the Permian extinction was also
caused by acid rain. She is engaged in a comparison of the
features in the Black Triangle with features of the Permian
extinction. For example, what do you expect in an area loaded
with dead decaying trees? Answer, something that likes this sort
of thing, one of my favorite subjects - fungi. In the Italian Alps,
Looy and colleagues have found layers of rock and sediment laid
down during the Permian extinction. And sure enough, these
layers are loaded with fossils of microscopic wood-eating fungi.
If the Permian extinction was due to acid rain, where did it come
from? There weren''t any humans to blame. Looy and others
believe that acid rain developed from volcanic gases emitted
during truly humongous volcanic activity. Indeed, volcanoes are
considered as candidates for being the culprits in many mass
extinctions. Improved dating techniques have pinned down one
period of major league volcano activity in Siberia to the time of
the Permian extinction. If you''ve seen pictures of the ongoing
volcanic activity on the island of Hawaii, it''s nothing compared
to what happened in the area known as the Siberian Traps. The
prolonged and massive flows of lava from cracks in the earth
covered all of Siberia. In some places the lava is over 2 miles
thick. One estimate is that enough lava was ejected to cover the
whole earth to a depth of 20 feet!
However, all the ducks aren''t lined up sufficiently to convince
the jury that volcanoes are the true culprits in the Permian
extinction. Some maintain that it requires a more catastrophic
event, like the one that killed the dinosaurs. Rather than taking a
few million years, they believe that the whole messy job was
done in a geological instant of say 100,000 years. Others think
that diminished coastal areas were involved due to the fact that
almost all the land masses on earth had coalesced into one big
glob known as Pangaea. Critics of this theory point out that
Pangaea was formed well before the extinctions took place.
Others suggest massive glaciation, possibly caused by volcanoes
spewing enough ash into the atmosphere to block the sun''s rays
and cool the earth. As I recall, some years ago we experienced a
slight cooling due to the eruption of Mount Pinatubo in the
Philippines. Other possibilities include oxygen depletion causing
loss of sea life or emissions of methane gas from methane ice in
the sea. We discussed this methane ice in an earlier column. It''s
not easy to pin down the criminal in a 250 million-year-old
murder case!
But what about the survivors of the Permian affair? Skeletons of
one of the plant-eating synapsids called Lystrosaurus have been
found from periods dating both before and after the calamity.
Lystro was lucky because its mortal enemy, that saber-toothed
gorgon, didn''t make it. Without the gorgons to eat them, the
Lystros and other synapsids spread all over the place from Russia
to Antarctica. Eventually, dinosaurs evolved and one line of
synapsids spawned the first mammals. With the dinosaurs
around, I imagine the mammals that evolved were agile enough
to scurry away from the dinosaurs or were too small to satisfy a
dinosaur''s hearty reptilian appetite.
When that object from outer space knocked out the dinosaurs, the
survivors of that K-T extinction included some of these small
rodent-size mammals. During the past 65 million years, these
mammal survivors evolved into a host of other mammals,
including us.
Viva Lystrosaurus and the Permian and K-T extinctions! Let''s
hope we survive the next one!
Allen F. Bortrum
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