Extinction
Part 2 of 5
Nicholaus Steno
and Robert Hooke argued for a naturalistic interpretation of fossils.
One problem still existed. What to do with unfamiliar
organisms that appear in the fossil record?
Today,
extinction, the permanent disappearance of a species, is an all
too familiar
concept.
In recent history we have witnessed
the extinction of many species due to the human activities of hunting
and habitat destruction. As little as 200 years ago many people thought
extinction was impossible. Theology fueled opposition to the idea
of extinction. People believed that the biosphere constituted a perfect
creation. The concept of extinction was contrary to several deeply
held Christian beliefs. First, was the concept of divine providence.
An all-powerful and all-loving God would never allow any creature
to become extinct. This is illustrated in the story of Noah’s
ark. God would not suffer any species to become extinct and thus
ordered Noah to populate the ark with two of each creature. Second,
was the idea of plenitude (fullness of nature). God’s creation
was perfect and an organism’s extinction would render it incomplete.
Finally, was the concept of a “Great Chain of Being”.
This chain linked animals to human to angels to God. Extinction would
take away links in the chain leading to its destruction.
Thomas Jefferson (1743-1826) strongly believed in the Great Chain
of Being. Jefferson and many others argued that the strange organisms
found in the fossil record must still exist in unexplored parts of
the world. A large fossil claw prompted Jefferson to ask Lewis and
Clarke to look for a giant prairie lion on their expedition. This
claw was later found to be a part of the extinct giant ground sloth.
The great French anatomist Georges Cuvier (1769-1832) established
extinction as a fact in a historic lecture given to the French Institute
in 1796. Cuvier talked about mammoths, woolly rhinos, giant cave
bears, and the sea reptile mosasaur in his lecture. In his paleontological
studies Cuvier came to recognize what we now call mass extinctions
at the end of the Permian and Cretaceous periods. Cuvier developed
the theory of catastrophism. Cuvier believed supernatural cataclysms
occurred before Noah's flood (antideluvial) and were regional not
global.
Stephen
J. Gould (1941-2002), American paleontologist and writer, believed
that extinction is
needed to tell time and is the motor
of evolution. If all the species stayed the same there would be no
way to tell geologic time. Furthermore, if species didn’t disappear
there would be no room for new ones to evolve. For example, during
the reign of the dinosaurs, mammals never got bigger than an ordinary
house cat. If the dinosaurs had not died out there is no reason to
believe that mammals would have increased in size and, in that case,
we would not be here.
It is ironic, that in the last two hundred years scientist have
gone from believing that extinction is impossible to establishing
that 99.9% of all the species that have ever existed on Earth are
now extinct.
Continue
to Part 3
Bibliography
for Echoes of Life Through Time
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