Download Charles Darwin

The Evolution of
Evolution
Historic Ideas about Organism Change
Aristotle
(384 - 322 B.C.)
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“Ladder of life”
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Nature is ordered from
lower to higher
No vacant rungs
No movement up or
down the ladder
Included living and
non-living things
Jean-Baptiste Lamarck
(1744-1829)
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First scientist to propose
a mechanism for how
organisms change (1809)
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His idea: “Inheritance of
Acquired Traits”
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Greater use of a body part
would change it, and the
change would pass on to
the organism’s offspring.
Lamarck’s Assumptions
1.
Organisms have a
desire to change.
They have an
inborn urge to
better themselves
for their
environment.
Ex: Birds tried to fly and
eventually grew wings
because of their
efforts.
Lamarck’s Assumptions
2. Organisms can change
shape by using or not
using their bodies.
Ex: The wings of a bird that
does not fly would get
smaller from generation to
generation and the wings
would eventually
disappear.
Lamarck’s Assumptions
3. Organisms can pass
on acquired traits to
their offspring.
Ex: If an animal developed
muscles from lifting
weights during its lifetime,
it could pass those
muscles on to its
offspring.
Charles Darwin
(1809-1882)
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English naturalist
Traveled around the world on the
Beagle (1831); famously stopped
in the Galapagos Islands
Observed many species and
fossils
Particularly studied finches,
tortoises, blue-footed boobies
The Galapagos Islands (Ecuador)
“Darwin’s finches”
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Darwin noticed that
finches were different
on each Galapagos
Island.
He concluded that the
different finches had
descended from a
common ancestor and
had changed to be
able to do and eat
different things.
Examples of Natural Selection
B. Darwin’s Finches: Darwin noticed that
different species of finches on different
Galapagos Islands had differently shaped
beaks. There were also different types of
seeds found on each island.
WHY DO THE DIFFERENT SPECIES
HAVE DIFFERENT BEAK SHAPES?
Examples of Natural Selection
A. Peppered Moths: (Discuss with a
neighbor) – There are two forms of
peppered moth, light and dark. Before the
Industrial Revolution, light moths survived
and reproduced more effectively. After the
Industrial Revolution, dark moths survived
and reproduced more effectively.
WHY WAS THIS THE CASE?
2 Forms of Moth:
Light and Dark
Before
Industrialization
After
Industrialization
Darwin’s “Descent with Modification”
After his studies, Darwin came up with 4 main ideas…
1.
2.
3.
4.
Individuals differ, and some of
this variation can be inherited.
Organisms produce more
offspring than can survive; thus
they have to compete for
resources, and only the most fit
will survive and reproduce.
The most fit organisms pass on
their heritable traits to their
offspring.
Species alive today are
descended with modification
(change) from their ancestors.
“Descent with modification” definitions
“Descent with modification” means…
…change in organisms over time (many generations)
“Natural Selection” means…
… “pressure” the environment puts on the specific traits
that affects their ability to survive
Hey! I thought this unit was about evolution??
“Evolution” means…
… change over time
Therefore we now call Darwin’s idea “biological evolution.”
Lamarck’s explanation for
the giraffe’s long neck:
Darwin’s explanation for the
giraffe’s long neck:
Darwin was influenced by the work
of others…
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Thomas Malthus – Populations
James Hutton and Charles Lyell – Geological
Record
Farmers – Breeding
Thomas Malthus
(1766-1834) British clergyman
and scholar
His prediction:
 the human population
would grow faster than
the space and food
supplies needed to
sustain it.
 The only checks on the
human population would
be war, famine, and
disease.
Influence of Malthus on Darwin
Malthus’ theory of population growth was observed
by Darwin in other animal populations as well.
In nature, Darwin saw many organisms that
produced many offspring. Most died.
Darwin wondered, what determines which
individuals survive and reproduce?
James Hutton, Charles Lyell &
Georges Cuvier
British Geologists
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Hutton is considered the “father of
modern geology”
Based on layers found in rock
structures, Lyell proposed that
Earth is millions of years old
Lyell proposed that geological
features could be built up or torn
down over long periods of time =
uniformitarianism
Cuvier Summarized that layers
were different due to catastrophes
= catastrophism
Grand Canyon, Arizona
Influence of Geology on Darwin
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After reading Lyell’s book, Darwin was
convinced that Earth was old.
Darwin reasoned that if geological phenomena
could change the earth, then life on Earth
could change as well.
Farmers
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Farmers recognize
that within a
population, there is
natural variation.
Farmers improve their
plants and animals
through selective
breeding.
Influence of Farmers on Darwin
Farmers bred the plants or animals with the most
desired traits.
This process of humans allowing only the best
organisms to reproduce is called artificial
selection.
Adaptation vs. Acclimatization
⦿ Adaptation
– Change in a population
over time.
› Example – whales loosing walking limbs
⦿ Acclimatization
– Change in an
individual in its lifetime.
› Example: 40° in the Fall and 40° in the Spring
⦿ Everyday
vs. Scientific Theories
Everyday – an opinion
“My theory is that gas prices are going
up because the gas stations are trying
to make more money.”
Scientific - An extensively tested, well
supported explanation.
“The theory of evolution states that over loooong
periods of time, organisms change to fit their
environment.”