A CENTURY OF PROGRESS 145
Darwin’s approach to evolution,
like the rest of his wide-ranging
work in natural history, was
cautious, careful, and deliberate.
He proceeded step by step,
amassing great quantities of
evidence along the way. Over
almost 30 years, he integrated
his extensive knowledge of fossils,
geology, plants, animals, and
selective breeding, with concepts
from demography, economics, and
many other fields. The resulting
theory of evolution by natural
selection is regarded as one of the
greatest scientific advances ever.
The role of God
In the early 19th century, fossils
were widely discussed in Victorian
society. Some regarded them as
naturally formed rock shapes,
and nothing to do with living
organisms. Others saw them as
the handiwork of the Creator, put
on Earth to test believers. Or they
thought that they were the remains
of organisms still alive somewhere
in the world, since God had created
living things in perfection.
In 1796, the French naturalist
Georges Cuvier recognized that
certain fossils, such as those
of mammoths or giant sloths, were
the remains of animals that had
become extinct. He reconciled this
with his religious belief by invoking
catastrophes such as the Flood
depicted in the Bible. Each disaster
swept away a whole assortment of
living things; God then replenished
Earth with new species. Between
each disaster, each species
remained fixed and immutable.
This theory was known as
“catastrophism” and it became
widely known following the
publication of Cuvier’s Preliminary
Discourse in 1813.
However, at the time Cuvier
was writing, various ideas based
on evolution were already in
circulation. Erasmus Darwin,
the free-thinking grandfather
of Charles, proposed an early,
idiosyncratic theory. More
influential were the ideas of
Jean-Baptiste Lamarck, professor
of zoology at France’s National
Museum of Natural History. HisSee also: James Hutton 96–101 ■ Jean-Baptiste Lamarck 118 ■ Gregor Mendel 166–71 ■ Thomas Henry Huxley 172–73 ■
Thomas Hunt Morgan 224–25 ■ Barbara McClintock 271 ■ James Watson and Francis Crick 276–83 ■ Michael Syvanen 318–19
Creation is not an event that
happened in 4004 BCE; it is a
process that began some
10 billion years ago and
is still under way.
Theodosius DobzhanskyPhilosophie Zoologique of 1809
articulated what was perhaps the
first reasoned theory of evolution.
He theorized that living beings
evolved from simple beginnings
through increasingly sophisticated
stages, due to a “complexifying
force.” They faced environmental
challenges on their body physiques,
and from this came the idea of
use and disuse in an individual:
“More frequent and continuous use
of any organ gradually strengthens,
develops and enlarges that organ...
while the permanent disuse of
any organ imperceptibly weakens
and deteriorates it...until it finally
disappears.” The organ’s greater
power was then passed to
offspring, a phenomenon that
became known as inheritance
of acquired characteristics.
Although his theory came to be
largely discounted, Lamarck was
later praised by Darwin for having
opened up the possibility that
change did not occur as a result of
what Darwin disparagingly termed
“miraculous interposition.”Adventures of the Beagle
Darwin had plenty of time to muse
on the immutability of species
during an around-the-world voyage
aboard the survey ship HMS
Beagle, in 1831–36, under captain
Robert FitzRoy. As expedition
scientist, Darwin was charged
with collecting all types of fossil,
plant, and animal specimens, and
sending them back to Britain from
each port of call. ❯❯By studying the fossil record, Georges
Cuvier established that species had
become extinct. But he believed that
the evidence pointed to a series of
catastrophes, not gradual change.