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The Origin of Life
• Life on Earth began about 3.5 billion
years ago.
• The Earth was covered in a hot, thin
soup of water and organic materials.
• Over time, the molecules became
more complex
• This was explained by Miller and
Urey’s Experiment in the 1950s
The Origin of Life: The
Heterotroph Hypothesis
The Earth’s
atmosphere was
different.
Branching Tree Diagram for Evolution
FOSSILS
Fossils Form In Sedimentary Rock
-over time, pieces of
earth erode and are
worn away by wind and
water. Layers of
eroded earth are
deposited on top of
each layer. These
layers press down until
the bottom layers turn
into rock.
Preservation in Volcanic AshEruption of Vesuvius in 80 BC
Refrigeration of Soft Parts
This frozen baby wooly
mammoth probably lived
22,000 years ago. It was
found in Siberia in 1997.
Ice Man
(Austria)
Insects
in
Amber
Intermediate
Forms
vestigial leg bones
appendix
Vestigial Structures
Comparison of Proteins:
Hemoglobin Comparison
Species
Amino Acid Differences
Gorilla
1
Rhesus monkey
8
Mouse
27
Chicken
45
Frog
67
Lamprey
125
Evidence from Early Stages
of Development: Embryology
Lamarck:
Theory of Use and Disuse
The selective use or
disuse of organs leads to
acquiring or losing certain
traits during an organism’s
lifetime.
appendix
These traits can then be
passed onto offspring.
Over time, there is a
change in the species.
This theory is not true!
Voyage of the Beagle
1859- On the Origin
of Species by Means
of Natural Selection
is written.
Darwin
Marine Iguana
Darwin found
different
characteristics on
different islandseach well suited to
their environment.
Galapagos Tortoises
Flightless
Cormorant
Theory of Natural Selection
•Species are not perfect or unchanging.
•There are different traits among offspring
called variation. This variation is inherited.
•There is competition for resources•a struggle for existence.
• This leads to survival of the fittest.
Sources of Variations
•mutations
Changes in Species Resulting From:
•resistance (insects, bacteria)
•industrial melanism (peppered moths)
Industrial MelanismKettlewell’s moths
European
peppered moths
have 2 color
variations. The
darker moths
(with more
melanin) were
rare until
industrial
pollution in the
1850s, when
tree trunks
darkened due to
soot.
Species – a
group of
organisms that
can breed
together under
natural
conditions to
produce fertile
offspring.
X
Tiglon
Liger
Father =lion
Father = tiger
Mother =tiger
Mother = lion
sterile and do not mate under
natural conditions- not a species
Gradualism versus Punctualism
in Evolution
Most of the time evolution occurs over
many, many years. This is called Gradualism.
Sometimes it occurs very quickly over several
generations. This is called Punctualism.
When the peppered moths changed cover
over several generations, this was an example
of ???