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Old Earth, Ancient Life:
Georges-Louis Leclerc, Comte de Buffon
No single naturalist of the 1700s epitomizes the revolutionary changes
that the Enlightenment brought to the study of nature more than Georges-Louis
Leclerc, Comte de Buffon (1707-1788). In the 1600s most naturalists believed
the world was a few thousand years old and that species
were created separately and organized into an unchanging hierarchy, with
humans positioned just below the angels. In the 1800s, Darwin described
a world that was inconceivably old, one in which life gradually changed
from one form to another without any need for direct supernatural intervention.
Roughly midway between those two views—both chronologically and intellectually—was
the remarkable Georges-Louis Leclerc Buffon.
Buffon’s career centered on a single enormous project: an encyclopedia
he called Histoire Naturelle, which he planned to contain everything
known in his day about the natural world. (Buffon only managed to publish
36 out of his projected 50 volumes before he died.) To create it, he was
able to draw on his own astonishing expertise, which ranged from astronomy
to botany, as well as the knowledge of experts he consulted. But in writing
his encyclopedia he did not merely parrot the opinions of others. Instead,
he tried to explain all of the facts he amassed with overarching theories
about the planet and its inhabitants.
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Buffon proposed that the debris flung out from a comet’s collision with the sun became the planets. |
A non-Biblical explanation of Earth’s history
Buffon realized that to interpret the world, he had to understand its
history. And despite censures from the Church, he did not rely on the
Bible as a strict guide to that history. Instead, he used the new physics
of Isaac Newton to conjecture how matter in motion might have formed the
Earth. He proposed that a comet striking the sun had broken off debris
that became the planets of the solar system. Initially, the Earth was
scorching, but gradually it cooled until molten rock turned to dry land
and clouds rained down to form oceans. Buffon estimated the entire process
took over 70,000 years. To most Europeans of Buffon’s time, who considered
the Earth to be fewer than 7,000 years old, this was practically an eternity. |
Spontaneous origins of life
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Buffon believed that modern Indian and African elephants were migratory descendants of Siberian mammoths.
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Buffon argued that life, just like Earth, had a history. Like many other
Enlightenment thinkers, he thought that it could be generated spontaneously
under the right conditions. In the hot oceans of the early Earth, Buffon
claimed that vast amounts of life were generated from unorganized matter—even
large animals sprang into existence. In time, as the world’s climate
cooled, many animals migrated to the tropics. Their migration made sense
of the discoveries in Buffon’s day of fossil elephants in Siberia
and North America, while living elephants were only found in Africa and
South Asia (see figure, right). The Siberian species gave rise to today’s elephants,
while the North American forms simply became extinct.
Change through migration
According to Buffon, life originated already divided into a number of
distinct types—an “internal mould” that organized the organic
particles that made up any individual creature. But during migrations,
life changed. As a species moved to new habitats, the supply of organic
particles that could create new individuals changed, and the particles
could thereby change a species’ mould. Buffon was, in other words,
proposing a sort of proto-evolution. While he thought that this process
couldn’t produce radically new kinds of body plans, he did claim
that it could account for the geographical distribution of similar species
around the world.
Buffon’s theories were visionary yet doomed, because they were based
on the relatively skimpy evidence that eighteenth-century naturalists
had at their disposal. His estimate of the Earth’s age turned out
to be far too young, and his notions of biological change were not based
on a coherent mechanism. Yet his theories foreshadowed some of the most
important developments in the natural sciences in the decades that followed
his death—from Cuvier’s
discoveries about extinctions,
to the evidence that Lyell and
other geologists found for a vast age of the planet and life itself, to Darwin’s own theory
of evolution.
It may be true that no single idea of Buffon’s has withstood the
test of time. But his work was still a milestone of science because he
thought about the Earth and life in ways that few had before—both
life and the Earth had a history. |
