NAME__________________________________DATE_________________PERIOD____________
Comparing Primates
Background:
In The Descent of Man, the English naturalist Charles Darwin formulated the hypothesis that human beings
and other primates have a common ancestor. A hypothesis is a suggested explanation for observed facts.
All scientific hypotheses, including that of Darwin, are based on observations.
Darwin observed that human beings and other primates differ in many important ways. Although all
primates have opposable thumbs, the human hand is capable of more refined and exact movements than
those of other primates. The human braincase, or cranium, has more volume and more mass than those of
other primates. In addition, human beings are bipedal, or able to walk on two limbs. Other primates use all
four limbs for locomotion. Being bipedal frees the arms and hands for other tasks, such as toolmaking.
Darwin regarded these human traits as adaptations, resulting from natural selection. The adaptations of
other primates, he suggested, evolved differently.
More recently, biochemists have determined that certain proteins found in different primates contain many
of the same amino acid sequences. Scientists reason that because proteins are produced by DNA, human
beings and other primates must have a similar genetic makeup. Paleontologists have also found fossil
remains that provide evidence that all primates came from a common ancestor. These and other
observations lend support to Darwin’s hypothesis of human origins.
Objectives:
Create a cladogram that depicts the evolutionary relationships between different primate
species by analyzing a variety of data.
Materials: Metric ruler
Pencil
Protractor
Procedure:
Part A-Comparing Amino Acid Sequences in Vertebrate Proteins:
1. Figure1 shows the amino acids found in selected sites in the hemoglobin of different vertebrates.
2. Count the number of molecules of each amino acid in human hemoglobin. Record the total in
Data Table 1.
3. Repeat step 2 for each of the other vertebrates.
4. Going from left to right, note the position of each amino acid.
5. Count the number of similarities in the amino acid positions between humans as compared with
each of the other vertebrates.
6. Record your observations in Data Table 2.
7. Repeat step 5 only this time count the number of differences.
8. Record your observations in Data Table 2
Part B-Comparing Primate Features:
1. Determine the relative size of the lower jaw of each primate by measuring the length in
millimeters of lines ab and bc in Figure 2.
2. Record the lengths in Data Table 3.
3. Record the product of these lengths in Data Table 3.
4. Determine the angle of the jaw by using a protractor to measure the angle xy in each primate skull
in Figure 2.
5. Record your observations in Data Table 3.
6. Examine the teeth of each of the three primates in Figure 3.
7. Count the number of incisors, canines, premolars, and molars of each primate in Figure 3.
8. Record your observations in Data Table 4.
9. Examine the two skeletons in Figure 4.
10. Compare both views of skeleton A with those of skeleton B.
11. Answer Questions 1 and 2 in the Data and Observation section
NAME__________________________________DATE_________________PERIOD____________
Data and Observations:
Figure 1.
Amino Acid Positions in the Hemoglobin of Some Vertebrates
PRIMATES
Human Beings
SER
THR
ALA
GLY
ASP
GLU
VAL
GLU
ASP
THR
PRO
GLY
GLY
ALA
ASN
ALA
THR
ARG
HIS
Chimpanzee
SER
THR
ALA
GLY
ASP
GLU
VAL
GLU
ASP
THR
PRO
GLY
GLY
ALA
ASN
ALA
THR
ARG
HIS
Gorilla
SER
THR
ALA
GLY
ASP
GLU
VAL
GLU
ASP
THR
PRO
GLY
GLY
ALA
ASN
ALA
THR
LYS
HIS
Baboon
ASN
THR
THR
GLY
ASP
GLU
VAL
ASP
ASP
SER
PRO
GLY
GLY
ASN
ASN
ALA
GLN
LYS
HIS
Lemur
ALA
THR
SER
GLY
GLU
LYS
VAL
GLU
ASP
SER
PRO
GLY
SER
HIS
ASN
ALA
GLN
LYS
HIS
NONPRIMATES
Dog
SER
SER
GLY
GLY
ASP
GLU
ILU
ASP
ASP
THR
PRO
SER
ASN
LYS
ASN
ALA
ALA
LYS
LYS
Chicken
GLN
THR
GLY
GLY
ALA
GLU
ILU
ALA
ASN
SER
PRO
GLU
THR
LYS
ASN
SER
GLN
ARG
ALA
Frog
ASP
SER
GLY
GLY
LYS
HIS
VAL
THR
ASN
SER
ALA
HIS
ALA
LYS
ASN
ALA
LYS
ARG
ARG
Data Table 1.
Number of Molecules of Different Amino Acids in Some Vertebrates
Amino
Acid
Abbreviation
Alanine
ALA
Arginine
ARG
Asparagine
ASN
Aspartic
Acid
ASP
Glutamine
GLN
Glutamic
Acid
GLU
Glycine
GLY
Histidine
HIS
Isoleucine
ILU
Lysine
LYS
Proline
PRO
Serine
SER
Threonine
THR
Valine
VAL
Human
Chimp
Gorilla
Baboon
Lemur
Dog
Chicken
Frog
NAME__________________________________DATE_________________PERIOD____________
Data Table 2.
Similarities and Differences in Amino Acid Positions in Hemoglobin
Number of Amino Acid
Number of Amino Acid
Position Similarities
Position Differences
Human and Chimpanzees
Organisms
Human and Gorillas
Human and Baboon
Human and Lemur
Human and Dog
Human and Chicken
Human and Frog
Figure 2.
Primate Skulls
Data Table 3.
Skull
A: Gorilla
B: Chimpanzee
C: Human
Comparison of Three Primate Skulls
Length of Lower
Depth of Lower
Area of Lower Jaw
Jaw (mm) (ab)
Jaw (mm) (bc)
(mm2) (ab X bc)
Angle of Jaw
NAME__________________________________DATE_________________PERIOD____________
Figure 3.
Teeth of Three Primates
Data Table 4.
Jaw
Number of
Incisors
Comparison of Primate Teeth
Number of
Number of
Canines
Premolars
A: Gorilla
B: Chimpanzee
C: Human
Figure 4.
Two Primate Skeletons
Human
Gorilla
Number of
Molars
NAME__________________________________DATE_________________PERIOD____________
Skeleton Analysis
1.
Describe three differences between the human and the gorilla.
Questions.
1. From your observations in Data Table 2, which primate is most closely related to the human
being?
2.
Which non-primate vertebrate listed in Data Table 2 is most closely related to the human
being?
3.
Which non-primate vertebrate is least closely related to the human being?
4.
Which of the three primates shown in Figure 2 has the largest brain? What do you think is the
name of this primate?
5.
What is the relationship between jaw size and brain size in these three primates?
6.
From your observations in Data Table 4, what dental characteristics do the primates have in
common?
7.
Reexamine Figure 3. How would the diet of primate A differ from the diet of primate C?
8.
What is an advantage of being bipedal?
9.
Certain fossil evidence indicates that the primate ancestors of humans lived in areas where
trees were scattered instead of clustered together. How might this type of environment have
affected the development of bipedalism in humans?
Cladogram
Construct a cladogram that depicts the evolutionary relationships between the following
organisms. Use data from this activity to assist you. Include all the organisms listed and
include their shared derived characteristics on the main line.
Characteristic Chart
Human
Chimpanzee
Frog
Dog
Chicken
Gorilla