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Evolution
Evolution
• the underlying theme woven
throughout the text, refers to the
processes that have transformed
life on earth from its earliest forms
to the enormous diversity that
characterizes it today
24 November 1859
On Origin of the
Species by
Means of
Natural
Selection
by Charles
Darwin
Origin of the Species
Made 2 major points:
–Species evolved from ancestral
species and were not created
–Natural Selection is the
mechanism that could result in
this evolutionary change
Origin of the Species
• Challenged Western culture
• Darwin’s viewpoint contrasted
sharply with the currently
accepted concepts:
–the earth’s age
–the 1 week creation
Origin of the Species
Many Greek philosophers believed
in the gradual evolution of life
However:
–Western Culture was
influenced by Plato and
Aristotle
Platonic Philosophy
Idealism – essentialism
2 coexisting worlds
 an ideal eternal “real” world

an illusionary imperfect world
“ours”
Platonic Philosophy
• Variations in plant and animal
populations were imperfect forms
of the ideal forms
• Evolution would be
counterproductive in a world
where ideal forms were already
perfect
Aristotle Philosophy
• Organisms range from simple to
complex. Occupied levels of an
ascending ladder. (scala naturae)
• Species are fixed and do not
evolve
• Lasted for 2000 years
Creationist - Essentialist
Species were individually created
and fixed became embedded I
western thought as the Old
Testament account of creation
from the Judeo-Christian culture
fortified prejudice against
evolution
Creationist - Essentialist
• Natural Theology: a philosophy
that a creator’s plan could be
revealed by studying nature
• Adaptations of organisms were
evidence that a creator had a
purpose for each
Creationist - Essentialist
• Natural Theology’s major
objective was to classify each
species of God’s created steps of
the Aristotle ladder
Carolus
Linnaeus
1707-1778
Carolus Linnaeus
• A Swedish physician and botanist,
sought order in the diversity of life
• ad majorem Dei gloriam
–For the greater glory of God
Carolus Linnaeus
• Known as the father of taxonomy
– binomial nomenclature
• Developed a classification
scheme which included a ranking
hierarchy
Carolus Linnaeus
• The clustering of species in
taxonomic groups did not imply
evolutionary trends
• Purpose was to reveal God’s plan
Deus creavit, Linnaeus disposuit
(God creates, Linnaeus arranges)
Georges Cuvier
1769-1832
Georges Cuvier
• Realized that life’s history was recorded in
fossil-containing strata and documented
the succession of fossil species in the
Paris Basin
Georges Cuvier
• Noted that each strata was
characterized by unique set of
fossil species and that the older
the statrum, the more dissimular
the flora and fauna from modern
life forms
Georges Cuvier
• Understood that extinction had
been a common occurance in the
history of life since, new species
appeared and others disappeared
Georges Cuvier
• He was still an opponent to
evolution:
–Differences in species due to
catastrophic events (droughts, fires
floods)
Georges Cuvier
• New species result of:
–Localized catastrophe resulted in
mass extensions
–Repopulation of out side species
Theories of Ecological
Gradualism
• Gained popularity that would
influence Darwin’s concept
Theories of Ecological
Gradualism
• Principle that profound change is
the cumulative product of slow,
continuous process
Theories of Ecological
Gradualism
• Proposed by James Hutton
–1875 Scottish Geologist
Theories of Ecological
Gradualism
• He proposed that we look it was
possible to explain the various
land forms by looking at
mechanisms currently operating
in the world
• example: canyons formed by
erosion exposing fossils
Charles Lyell
• Expanded
Huton’s concept
into the theory
called
uniformitarianism
Charles Lyell
• Uniformitarianism:
–in this theory, geological processes
are uniform and have operated from
the origin of the Earth to the
present.
Charles Lyell
• Idea that the geological
processes are so uniform that
their rates and effects must
balance out through time
• Example: process of mountain
building is followed by erosion
Darwin
• Rejected uniformitarianism but
was intrigued by the conclusions
of Hutton and Lyell
–1. Earth must be ancient (>6000 yr)
–2. substantial change could occur
over time
Jean Baptiste Lamarck
• First published a
document trying
to explain the
model of
evolution in 1809
Jean Baptiste Lamarck
• Believed that evolution was driven
by innate tendency toward
increasing complexity
– As organisms attain perfection they
become better and better adapted
to their environment
Jean Baptiste Lamarck
Proposed 2 mechanisms
1. Use and Disuse
use it or loose it
2. Inheritance of acquired
characteristics
by genetics
• Althought his theory was in error, Lamarck
deserves credit for proposing:
– 1. Evolution is the best explanation for fossil
record and extant diversity of life
– 2. The Earth is Ancient
– 3. Adaptation to the environment is primarily
product of evolution