Download Comparative Anatomy

Name: _____________________________________________________ Per. _____ Date__________________________________
Evidence of Evolution Activity
Fossil Record
Paleontologist: A scientist studies fossils for clues of biological change as it relates to geological
change in the Earth’s history.
Strata: layers of the Earth’s crust
Observe the diagram of strata below.
1. What is the relationship between the depth of Earth’s strata and how much time has
passed?
2. What would this mean if we were examining fossils from different rock layers?
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This is a series of skulls and front leg fossils of organisms believed to be ancestors of the modernday horse.
2. Give two similarities between each of the skulls that might lead to the conclusion that these
are all related species.
3. What is the most significant change in skull anatomy (form) that occurred from the dawn
horse to the modern horse?
4. What is the most significant change in leg anatomy (form) that occurred from the dawn
horse to the modern horse?
5. In the diagram below, put the names of horse in order that you would expect to find them:
Check one: This layer is the: _____ oldest
_____ youngest
Check one: This layer is the: _____ oldest
_____ youngest
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Embryology
Developmental biologist: A scientist that studies how the processes of growth and development
occur and change over time.
Embryo: Earliest stage of development for an unborn eukaryote.
Organisms that are closely related may also have physical similarities before they are even born!
Take a look at the six different embryos below:
Use the chart to hypothesize which embryo is from each of the above organisms by matching the
letter of the embryo with the species:
Species
Embryo
(letter)
Human
Chicken
Rabbit
Species
Embryo
(letter)
Tortoise
Salamander
Fish
These are older, more developed embryos from the same organisms.
Use the chart to hypothesize which embryo is from each of the above organisms by matching the
letter of the embryo with the species.
Species
Human
Chicken
Rabbit
Embryo
(letter)
Species
Embryo
(letter)
Tortoise
Salamander
Fish
These are embryos at their most advanced stage, shortly before birth.
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Describe this change by answering the questions.
1. Look again at the six embryos in their earliest stages. Describe the patterns you see. What
physical similarities exist between each of the embryos? (name at least 3)
2. The human embryo was letter F. Which organism’s embryo became different from the
human embryo the earliest on in development?
3.
4.
What does this say about the relatedness of this organism and humans?
Which organism’s embryo was the same as the human embryo for the longest period
during development?
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Comparative Anatomy
Evolutionary biologist: A scientist that studies the origins and relatedness of living organisms.
They look at homologous and vestigial structures.
Shown below are images of the skeletal structure of the front limbs of 6 animals: human, crocodile,
whale, cat, bird, and bat. Each animal has a similar set of bones. Color code each of the bones and
mark them in this key:
Humerus [ ]
Carpals
[ ]
Ulna
[ ]
Metacarpals
[
]
Radius
[
Phalanges
[
]
]
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For each animal, indicate what type of movement this front limb is responsible for.
Animal
Human
Whale
Primary Functions
Using tools, picking up and holding objects
Cat
Bat
Bird
Crocodile
Compare the skeletal (bone) structure of each limb to the human arm. Relate the
differences you see in form to the differences in function.
Animal
Comparison to Human Arm in Form
Comparison to Human Arm in Function
Whale
Whale has a much shorter and thicker
humerus, radius, and ulna. Much
longer metacarpals. Thumb has been
shortened to a stub.
The whale fin needs to be longer to help in
movement through water. Thumbs are not
necessary, as the fins are not used for
grasping.
Cat
Bat
Bird
Crocodile
Homologous structures: Similar structures that perform different functions. These are seen in
organisms that are closely related.
1. Give an example of a homologous structure from this activity:
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Vestigial structures:
remnant structures that
once important in the
organism’s ancestors, but
no longer used in the
way.
were
are
same
The diagram to the right,
table below are vestigial
structures found in
humans.
and
For each, hypothesize
its function may have
what
been.
2. How do homologous and vestigial structures suggest an evolutionary relationship between
species?
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Molecular (DNA) Biology
Molecular (DNA) biologist: A scientist that studies the molecular basis of biological activity,
particularly DNA sequences and biochemistry.
Below are sequences of letters that stand for portions of the genes that code for α and β
hemoglobin (blood) proteins in different primates.
Compare the DNA sequences from the α hemoglobin for the thick-tailed bushed baby and
humans. Circle any differences in base pairs from the human sequence and record the total
differences in the data table on this page.
Primate Animal
Number of base pair differences for α
hemoglobin compared to humans
Number of base pair differences for β
hemoglobin compared to humans
Human
Thick-tailed
bush baby
Chimpanzee
Gorilla
Orangutan
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Compare the DNA sequences for β hemoglobin for the chimpanzee, gorilla, human, and orangutan.
Circle any differences in base pairs from the human sequence and record total differences in the
data table on the last page.
1. Based on the α hemoglobin and β hemoglobin data, which organism is most closely related to
humans?
2. Do any of the organisms have the same number of differences from human α hemoglobin or β
hemoglobin? In situations like this, how might you decide which is more closely related to
humans?
3. How does a similar DNA sequence suggest an evolutionary relationship between species?
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Synthesizing the multiple lines of evidence
Below is a real news article about human fossils. Now that you are an expert in evidence for
evolution, read the scenario and answer the prompts.
Baffling 400,000-Year-Old Clue to Human Origins
By CARL ZIMMER, New York Times Published: December 4, 2013
Scientists have found the oldest DNA evidence yet of
humans’ biological history. But instead of neatly clarifying
human evolution, the finding is adding new mysteries.
In a paper in the journal Nature,
scientists reported Wednesday that they had retrieved
ancient human DNA from a fossil dating back about 400,000
years, shattering the previous record of 100,000 years.
The fossil, a thigh bone found in Spain, had previously
seemed to many experts to belong to a forerunner of
Neanderthals.
But its DNA tells a very different story. It most closely
resembles DNA from an enigmatic lineage of humans known
as Denisovans. Until now, Denisovans were known only
from DNA retrieved from 80,000-year-old remains in Siberia,
4,000 miles east of where the new DNA was found.
The mismatch between the anatomical and genetic
evidence surprised the scientists, who are now rethinking
human evolution over the past few hundred thousand years.
It is possible, for example, that there are many extinct
human populations that scientists have yet to discover. They
might have interbred, swapping DNA. Scientists hope that
further studies of extremely ancient human DNA will clarify
the mystery.
Based on the anatomy of the fossils, Dr. Arsuaga has argued
that they belonged to ancestors of Neanderthals, which
lived in western Asia and Europe from about 200,000 to
30,000 years ago.
When Dr. Meyer and his colleagues drilled into the femur,
they found ancient human DNA inside, just as they had
hoped. “Our expectation was that it would be a very early
Neanderthal,” Dr. Meyer said.
But the DNA did not match that of Neanderthals. Dr. Meyer
then compared it to the DNA of the Denisovans, the ancient
human lineage that he and his colleagues had discovered in
Siberia in 2010. He was shocked to find that it was similar.
Does this information give you
evidence from (circle all that apply):
a)
b)
c)
d)
The Fossil Record
Embryology
Comparative Anatomy
Molecular or DNA
Highlight one statement that gives you
evidence.
Does this information give you
evidence from (circle all that apply):
a)
b)
c)
d)
The Fossil Record
Embryology
Comparative Anatomy
Molecular or DNA
Highlight one statement that gives you
evidence.
What type of evidence made the
scientists rethink human evolution?
What could have increased genetic
variation in the population?
What additional evidence would you
want to know in order to understand
the connection between these fossils?
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