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EVOLUTION
Darwin’s Book
The Journey Home
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On the journey home, Darwin studied his
specimens and observations, began to
develop theories
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Darwin knew that his ideas would be
considered radical – creationism was the
view of the time
The Ancient, Changing Earth
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Darwin studied work of Charles Lyell,
geologist
Lyell believed that natural, geological forces
shaped the face of the Earth, and that the
Earth was older than people believed
Darwin used Lyell’s work to explain fossils he
found
The Problem of Reproduction
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Darwin also influences by Thomas Malthus,
economist
Malthus observed that birth rate was much
higher than death rate, and this could lead to
the Earth being overrun by humans
Malthus argued that things like war, famine,
and disease were limiting factors on
population
The Problem of Reproduction
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Darwin saw that plants and animals
reproduce much faster than humans
If nothing were limiting this reproduction, the
plants and animals would have overrun Earth
centuries ago
This meant that the majority of offspring of
each species die, and only a few that survive
succeed in reproducing
Darwin’s Findings
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Darwin published On the Origin of Species
By Means of Natural Selection in 1859 (30
years after the Beagle)
Rushed publication to beat out Alfred Russel
Wallace, who had identical ideas
Darwin’s book described the huge amount of
evidence to support evolution and gave a
hypothesis as to how and why it occurs
Evolution
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Each living species is the result of millions of
years of evolution
Many of Darwin’s ideas have shown to be
accurate, while others have been disproved
The body of scientific knowledge built on the
concept of evolution is always changing
Life In Constant Motion
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The concept of evolution implies that life may
always be changing
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If enough variation exists in a species, and if
environmental conditions change, the
species will evolve.
Life In Constant Motion
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An example of this is the peppered moths in
England in the 1760s
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Another example is bacteria that cause
disease are constantly becoming antibiotic
resistant
Importance of Genetic Diversity
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Gives rise to inheritable variation, providing
the raw material for evolution
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Without genetic diversity, natural selection
would have nothing to act upon and species
could not change
Importance of Genetic Diversity
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Species MUST be able to change because of
natural processes and human influence
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Genetic diversity is a result of millions of
years of random mutation, natural selection,
and genetic drift