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Charles Robert Darwin
(1809-1882)
Chapter 14, Section 1
“nothing in biology makes sense except in the light of
evolution”-Theodosius Dobzhansky
Evolution
On the grandest scale, is all the changes that have
transformed life over time.
Essentially, it is the biological history of life on Earth.
Ideas that set the Stage for Darwin
► There
were 2 prevailing ideas about life on Earth:
 Life was created in its complexity and has remained
fixed (or unchanging) since this time
 The Earth was believed to be about 10,000 years old
and also relatively unchanging
► However,
these ideas were challenged as explorers
traveled and observed the incredible diversity of
life (past and present) and the nature of Earth’s
geological processes
Early Influences
► George
Buffon (mid-1700s): French naturalist;
collected fossils and noticed similarities and
differences; suggests Earth is older than 10,000yrs
► James Hutton (1785): English Geologist; suggest
geological forces that shape Earth’s surface are
slow and require long periods of time (Earth must
be millions of years old)
► Jean Baptiste Lamarck (1809): French naturalist;
Explains Buffon’s observations by making a
hypothesis that life evolves through the
inheritance of acquired characteristics
Lamarck’s Hypothesis
The Voyage
► In
1831, a 22-yr-old Darwin set sail on the
HMS Beagle on a 5 year cruise around the
world
► As a naturalist, he studied the geology,
plants, and animals encountered on the
voyage
Darwin’s Observations
► He
observed an immense amount of diversity in
the South American plants, animals, and fossils
 Some fossils resembled modern life forms, some had no
resemblance
 Life seemed well suited for the environment
► The
Galapagos Islands- islands had similar life
forms but varied in climate and vegetation
 Darwin inferred that the species on the different islands
had once been part of the same mainland species
The Galapagos Tortoises
Geological Influence
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On the voyage of the Beagle,
Darwin read the writings of
geologist Charles Lyell
Lyell proposed that the geological
processes that shape the Earth’s
surface today (erosion, deposition,
earthquakes, etc.) are the same
processes that shaped the Earth in
the past
Encouraged explaining the past in
terms of observable present day
processes
Darwin personally witnessed an
earthquake in the Andes Mtns and
observed marine fossils move
centimeters above the water line
He realized that slow, gradual
processes could cause enormous
change over vast periods of time
A Mechanism for Change
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When Darwin returned to
England, he could no longer
accept the idea of unchanging
life
He began contemplating a
mechanism for evolutionary
change
In 1838, he read the work of
Thomas Malthus (an economist
who wrote an essay on human
populations)
Malthus suggested that human
warfare, famine, and disease
would limit the growth of the
population
Darwin Publishes His Ideas
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In 1844, Darwin wrote a 200page essay that outlined his
idea, but did not publish it in
fear of controversy and doubt
Instead he spent the next
decade collecting evidence to
support his idea
Darwin received an essay from a
young naturalist, Alfred Wallace,
in 1858 proposing the same idea
for evolutionary change with
similar evidence
In 1859, Darwin published his
book The Origin of Species by
Means of Natural Selection
Darwin’s Two Main Ideas
Natural Selection
► His mechanism for
evolutionary change
► Organisms with
inherited traits best
suited for the
environment will
survive and reproduce
more often
Descent with Modification
► The species living on
Earth today descended
from common ancestral
species
► This is the most
controversial part of his
publication because it is
often misunderstood and
its religious conflict