Transcript Chapter 22 Descent with Modification

How did the diversity of life
originate?
• Through the
process of
Evolution
Evolution
• The processes that have
transformed life on earth from its
beginnings to today's diversity.
• Evolution is the most pervasive
principle in biology.
Theory vs theory
Theory
theory
• Hypothesis
supported
repeatedly by
data.
• Makes testable
predictions
• Layperson’s
definition.
• Confused with
hypothesis in
Science
Examples of Theory
•
•
•
•
•
Cell Theory
Big Bang Theory
Atomic Theory
Theory of Gravity
Theory of Evolution
Evolution
• Has itself "evolved" or changed
over time.
• Illustrates “Science as a Process”
Overview:
Endless Forms Most Beautiful
• A new era of biology began in 1859
when Charles Darwin published The
Origin of Species
• The Origin of Species focused
biologists’ attention on the great
diversity of organisms
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• Darwin noted that current species
are descendants of ancestral species
• Evolution can be defined by Darwin’s
phrase descent with modification
• Evolution can be viewed as both a
pattern and a process
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Charles Darwin
• The Darwinian revolution challenged
traditional views of a young Earth
inhabited by unchanging species
• To understand why Darwin’s ideas
were revolutionary, we must examine
them in relation to other Western
ideas about Earth and its life
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Pre-Darwinian Views
1. Greeks
2. Fixed Species
3. Catastophism
4. Hutton and Lyell
5. Lamarck
Pre-Darwinian Views
1. Greeks
2. Fixed Species
3. Catastophism
4. Hutton and Lyell
5. Lamarck
Greek Philosophers
1. Plato - Organisms are already
perfectly adapted to their
environments.
2. Aristotle - Organisms arranged on
a “scale of life” from simple to
complex.
Result
• No evolution.
• Life is already perfect and doesn’t
need to change.
• All the rungs on life's "ladder" are
already occupied.
Pre-Darwinian Views
1. Greeks
2. Fixed Species
3. Catastophism
4. Hutton and Lyell
5. Lamarck
Fixed Species Concept
• The creator had designed each and
every species for a particular purpose.
• Carolus Linnaeus interpreted organismal
adaptations as evidence that the Creator had
designed each species for a specific purpose
• Linnaeus was the founder of taxonomy, the
branch of biology concerned with classifying
organisms
Result
• No evolution.
• Created the viewpoint that all
species could be identified and
named (Taxonomy).
• A major factor in the Linnaeus
classification system.
Pre-Darwinian Views
1. Greeks
2. Fixed Species
3. Catastophism
4. Hutton and Lyell
5. Lamarck
Catastrophism
• Georges Cuvier
(1769-1832).
• Attempted to
relate fossils to
current life.
• Paleontology, the study of fossils, was largely
developed by French scientist Georges Cuvier
• Cuvier advocated catastrophism, speculating that
each boundary between strata represents a
catastrophe
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Catastrophism
• Fossils were the remains of species
lost due to catastrophe.
• No new species originated; species
could only be lost over time.
• Result - No evolution.
Pre-Darwinian Views
1. Greeks
2. Fixed Species
3. Catastophism
4. Hutton and Lyell
5. Lamarck
• Geologists James Hutton and Charles Lyell
perceived that changes in Earth’s surface can result
from slow continuous actions still operating today
• Lyell’s principle of uniformitarianism states that the
mechanisms of change are constant over time
• This view strongly influenced Darwin’s thinking
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
James Hutton
• 1795 - Gradualism
• Profound change is
the cumulative
product of slow,
but continuous
processes.
Result
• Changes on the earth were gradual, not
catastrophic.
• The study of fossils helped to lay the
groundwork for Darwin’s ideas
• Fossils are remains or traces of organisms
from the past, usually found in sedimentary
rock, which appears in layers or strata
Fig. 22-3
Layers of deposited
sediment
Younger stratum
with more recent
fossils
Older stratum
with older fossils
Charles Lyell
• 1797 - 1875.
• Incorporated
Hutton’s
gradualism into a
theory called
Uniformitarianism.
Uniformitarianism
• Geological processes have operated
at the same rate over the Earth’s
history.
• Result - The Earth must be VERY
old. (much older than 6000 years of
the fixed species concept).
• Idea that slow and subtle processes
can cause substantial change.
Pre-Darwinian Views
1.
2.
3.
4.
Greeks
Fixed Species
Catastophism
Hutton and Lyell
5. Lamarck
Jean Baptiste Lamarck
• Published
theory in 1809.
• Theory - Life
changed from
simple to
complex over
time.
Lamark
• Fossils were the
remains of past
life forms.
• Evolution did
occur.
Lamarck’s Hypothesis of Evolution
• Lamarck hypothesized that species evolve through
use and disuse of body parts and the inheritance of
acquired characteristics
• The mechanisms he proposed are unsupported by
evidence
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Lamark Mechanisms
1. Use and Disuse – Body parts used to survive become larger
and stronger.
– Body parts not used to survive deteriorate.
2. Acquired Characteristics
– Modifications acquired by use/disuse were
passed on to offspring.
Problem
• No knowledge of genetics.
• Acquired traits are not transmitted
offspring.
Lamarck’s Credits
• Did suggest correctly the role of
fossils in evolution.
• Did suggest that adaptation to the
environment is a primary product of
evolution.
• Another important figure
Thomas Malthus
• Essay on human population growth
in 1798.
• Disease, famine, homelessness,
and war are inescapable because
human populations grow faster
than food supplies.
• Darwin read Malthus.
Next time….
Charles Darwin and Natural
Selection