Download Evolution

Evolution
a change in a species over time
There are many types of evidence that
support the theory of evolution
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1. Anatomical Evidence:
2. Fossil Evidence:
3. Radioactive dating:
4. Relative Dating:
5. The Fossil Record
6. Embryological Evidence:
7. Chemical Evidence:
8. The Molecular Clock:
1. Anatomical Evidence:
• The French biologist Lamarck began to
look at similar structures in different
species.
• body parts
• Organs
• EX: bat’s wing, dolphin’s
• flipper,
Theory of Use and Disuse
• Lamarck
• that individuals would acquire or lose
structures through their use or disuse.
• EX: giraffe
Problems
• tailbone
• Appendix
• Ex: Another scientist tested this by cutting
the tails off mice.
2. Fossil Evidence:
• Fossils- the imprints or remains of plants or
animals that existed in the past
Carbon-14 is the radioactive form
of carbon
• half-life of 5,770 years
• All living things have
carbon-14
• when the organism
dies its C-14 starts to
decay.
• By measuring how
much C-14 is left
• tell how old the fossil
is.
3. Radioactive dating:
• elements that give off radiation as they
decay
• not all elements decay at the same rate
• half-life- measuring the decay rate
• non-radioactive element- the time it takes
for ½ of the element to break down
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Example:
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Carbon-14 is the radioactive form of carbon
half-life of 5,770 years.
when the organism dies, it decay.
By measuring how much C-14 is left in a
fossil, you can tell how old the fossil is.
A sample had 100 grams of C-14
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50 grams after 5770 years
25 grams = 11,540 years
12.5 grams =17,310 years
6.25 grams = 23,080 years
Theory of evolution so far
• 1. Anatomical
Evidence:
• 2. Fossil Evidence:
• 3. Radioactive dating:
• 4. Relative Dating:
• 5. The Fossil Record
5. The Fossil Record
• This includes ALL of the fossil evidence
scientists have collected
Example
• Some fossil bones of a leg and a foot were found in
sedimentary rock in the Mississippi River valley.
• Could tell from the
bones:
• 4 toes on each front
foot
• toes were spread apart.
Fossils found in the
same layers helped them
figure out it was
probably the size of a
cat, but had other traits of
a horse.
They named it
Eohippus = early horse.
They used radioactive dating
• To determine the age to be about 50 million
years.
Other fossils in those layers :
•climate was warm and wet
•possibly a tropical climate
surrounded by swamps and
mud
spread-apart toes would
help it to walk on mud
Scientists put all of this
information together to help form
a better idea
of what an organism looked like,
how it lived and how it changed
over time
mutations
• Changes of what organism looked like
ADAPTATION.
• a change that makes it easier for an
organism to survive is
• animals that could not adapt became extinct.
6. Embryological Evidence:
• Embryos are developing organisms.
• Scientists compare the embryos of different
species to see how closely related they are.
7. Chemical Evidence:
• Chemical similarities in the DNA of
different species = shows us how they might
be related.
• Ex: The DNA of a zebra and a quagga
8. The Molecular Clock:
• The more similar the structure of protein
molecules between 2 organisms, the more recent
their common ancestor.
• Scientists developed a time scale
• how long it takes proteins to change over time
• They use this to figure out how long ago a protein
changed.
http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage5.html
http://www.ucmp.berkeley.edu/education/explorations/tours/geo
time/clonus/transparent.gif
Now let's make a
similar timeline for
some of the major
events during the
history of life on
Earth.
Here are pictures of
some fossils. Your
goal is to put them
into the correct
order of when they
first appeared on
Earth.
Just click on the
fossils in order, from
the earliest to the
most recent.
http://www.ucmp.berkeley.edu/education/explorations/tours/geot
ime/clonus/transparent.gif
Theory of evolution
• 1. Anatomical
Evidence:
• 2. Fossil Evidence:
• 3. Radioactive dating:
• 4. Relative Dating:
• 5. The Fossil Record
• 6. Embryological
Evidence:
• 7. Chemical
Evidence:
• 8. The Molecular
Clock: