Evolutionary Theory
 Evolution
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What is your reaction to this term?
 Biological sciences
 Humans and Apes
shared last common ancestor
5-8 million years ago.
 Discoveries came
over a long time from a lot of
sources
 Charles Darwin
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Alfred Russel Wallace
 Middle
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Ages
Thought processes were static
Greek influence – Aristotle
 Scientific Revolution
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Europe vs. Arabia and India
 John
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Ray (1627-1705)
Coined terms species and genus
 Carolus Linnaeus
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(1707-1778)
Fixity of species
 George-Louis Le Clerc de Buffon (1707-1788)
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Change does occur in the universe
 Erasmus Darwin
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(1731-1802)
Charles Darwin’s Grandfather
 Jean-Baptiste Lamarck
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(1744-1829)
First to propose evolutionary process
 Georges Cuvier
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(1769-1832)
Opponent of Lamarck
 Charles Lyell (1797-1875)
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Wrote Principles of Geology
 Thomas Malthus (1766-1834)
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English clergyman and economist
 Mary
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Anning (1799-1847)
Discovered a lot of fossils
 John
Baptiste Lamack
was the first scientist
to produce an
explanation for the
evolutionary process.
 He believed that
species change was
influenced by
environmental change.
Georges Cuvier introduced
the concept of extinction
and the theory of
catastrophism.
 The view that the earth’s
geological landscape is the
result of violent
cataclysmic events.
 Cuvier promoted this view,
especially in opposition to
Lamarck.

 Thomas Malthus wrote
about the relationship
between food supply
and population increase.
 His essay on the
Principle of Population
led both Darwin and
Wallace to the principle
of natural selection.
 Charles
Lyell
developed the theory
of uniformitarianism.
 Discovered the first
complete fossil of
Ichthyosaurus, a large
fishlike marine reptile.
 She became known as
one of the world’s
leading “fossilists” and
contributed to the
understanding of the
evolution of marine life
over 200 million years
ago.
Ideas were formed while serving
as a naturalist on the voyage of the
HMS beagle.
 Darwin saw the importance of
biological variation within a
species.
 Recognized the importance of
sexual reproduction in increasing
variation.
 By 1844, Darwin had complete the
work that he would publish fifteen
years later.

A
naturalist who worked in South America and
Southeast Asia.
 Suggested species descended from other
species and new species were influenced by
environmental factors.
 Presented paper on evolution and natural
selection to the Linnean Society of London
jointly with Darwin.
 Charles Darwin (1809-1882)
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Discovered first credible mechanism for
evolutionary change
HMS Beagle
Finches and barnacles
 Alfred Russel Wallace (1823-1913)

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Developed own theory of natural selection
Wrote letter to Darwin
 Darwin’s formulation included:
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Potential for reproductive rates that outpace the
rate of food supply
The presence of biological variation within all
species
Constant competition among individuals for
survival
Favorable traits = increase in reproduction
Environment determines favorable traits
Favorable traits passed to offspring
Over long periods of time, successful variations
accumulate in populations
Geographical isolation may result in new species
 Peppered moth in
the UK
 Galapagos birds and beak thickness
 The
variation exhibited by dog breeds has been
achieved in a relatively short time through
artificial selection.
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A trait must be inherited if natural
selection is to act on it.
Natural selection can’t occur without
population variation in inherited
characteristics.
Fitness is a relative measure that changes
as the environment changes.
Natural selection can only act on traits
that affect reproduction.
 No one knew source of variation
that Darwin
explained
 Did not know how favorable traits were passed
down.
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Laws of heredity unknown – Mendel had not come
on the scene
DNA was not discovered until 1953
 Offensive to
Christians because in conflict with
Biblical versions of creation
 Evolution considered to be a fact by most
scientists today

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Accepted in part by Catholic Church and most
Protestants
Fundamentalists reject evolution
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Creationism
Intelligent Design
 Debate topic:

Should evolution be taught in public schools? If so
should Creationism also be taught?