Laboratory 12 Evidences of Evolution (lm pages 125–141) Fourth Edition

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Evidences of Evolution

(LM pages 125–141)
Fourth Edition

Section 12.2 now includes an Observation in which hominid skulls are compared. New illustrations have been added.

New or Revised Tables: 12.8 Other Hominid Craniums Compared to Human Cranium; 12.9 Other Hominid Faces Compared to Human Face; 12.10 Other Hominid Dentition Compared to Human Dentition


Instructions are grouped by exercise. Some materials may be used in more than one exercise.
12.1 Evidence from the Fossil Record (LM pages 126–130)

_____ Fossil collections are available from various supply houses and prices are variable.

12.2 Evidence from Comparative Anatomy (LM pages 131-138)

Skeletons or mounted forelimbs (LM pages 131-132)

_____ lizard

_____ bird (pigeon)

_____ bat

_____ bat skeleton plastomount

_____ cat

_____ human, adult (see Carolina’s “Skeletons: Human” section)

_____ chimpanzee

Comparison of Vertebrate Embryos (LM page132-133)

_____ slides, prepared: chick, reptile, fish embryos

_____ microscope, stereomicroscope

_____ lens paper

Comparison of Chimpanzee and Human Skeletons (LM page 133-136

_____ Complete chimpanzee and human skeletons

Comparison of Extinct Hominid skulls (LM page 136-138)

These skulls are available:

_____ Australopithecus afarensis skull

_____ Australopithecus aethiopicus cranium

_____ Australopithecus boisei cranium

_____ Homo erectus skull

_____ Homo heidelbergensis cranium

_____ Homo neanderthalensis skull

_____ Cro-Magnon cranium

12.3 Molecular Evidence (LM pages 138–140)

_____ Immunology and Evolution Experiment kit (Lab-Aids, Inc. 92)

_____ Immunology and Evolution Experiment replacement kit (Lab-Aids, Inc


_____ stirring rod, plastic; or toothpicks


12.1 Evidence from the Fossil Record (LM pages 126–30)

Geologic Timescale (LM pages 126–28)

Divisions of the Timescale (LM page126)

List the four eras in the timescale, starting with Precambrian time: Precambrian, Paleozoic, Mesozoic, Cenozoic

1. Why do you read the timescale starting at the bottom? The earliest dates are at the bottom.

2. During the Mesozoic era and the Jurassic period, the first flowering plants appear. How many million years ago was this? 199.6125.5

3. How do you know that the plants in this forest were not flowering trees as most of our trees are today? Flowering trees had not evolved yet. What type animal was diversifying at this time? amphibians

4. During what period and epoch did primates appear? Tertiary, Paleocene During what period and epoch did hominins appear? Tertiary, Pliocene What period and epoch is the age of Homo sapiens? Quaternary, Holocene
Dating Within the Timescale (LM page 128)

Why wouldn’t you expect to find human fossils and dinosaur fossils together in rocks dated similarly? Humans had not evolved yet.

Limitations of the Timescale (LM page 128)

Which of the animals shown in Figure 12.1 suffered the most during the P-T (Permian-Triassic) extinction? poriferans (sponges)

Which of the animals shown in Figure 12.1 became extinct during the K-T extinction? dinosaurs

Fill in the eras on the lines provided in Figure 12.1. Paleozoic, Mesozoic, Cenozoic

Fossils (LM pages 129-30)

The fossil record relies heavily on anatomical data. Why would that be? Because the anatomy of the organism is preserved as a fossil.

Observation Invertebrate Fossils (LM page 129)

1. One possible reason the Cambrian might be rich in fossils is that organisms now had shells and bones.

Table 12.2 Invertebrate Fossils Answers will vary according to the fossils in the kit.
Observation Vertebrate Fossils (LM pages 129-30)

Table 12.3 Vertebrate Fossils Answers will vary according to the fossils in the kit.
Observation Plants Fossils (LM pages 130)

Table 12.4 Plant Fossils Answers will vary according to the fossils in the kit.
Summary of Evidence from Fossil Record (LM page 130)

1. Fossils are past evidence of organisms preserved in the Earth's crust.

2. Younger fossils and not older fossils are more like living organisms.

3. In short, the fossil record shows that life has a history.

12.2 Evidence from Comparative Anatomy (LM pages 131-–38)

Observation: Vertebrate Forelimbs (LM page 131)

2. Label in Figure 12.3 the corresponding forelimb bones of the frog, the lizard, the bird, the bat, the cat, and the human. Follow the color coding to correctly label the bones.

3. Fill in Table 12.5 to compare bones in vertebrate forelimbs to ancestral condition.

Table 12.5 Comparison of Vertebrate Forelimbs*

Animal Bones That Resemble Bones That Differ from

Common Ancestor Common Ancestor

Frog h, m u, r, c, p

Lizard h, u, r, c, m p

Bird h, u, r c, m, p

Bat h u, r, c, m, p

Cat h, c, m, p u, r

Human u, r, c, m, p h

*Note: This comparison is relative, and student answers will vary.
4. Relate the change in bone structure to mode of locomotion in two examples.

Example 1: Bat: the radius is long, relative to the humerus. The phalanges are extremely long, and the bat’s skin is stretched out over the forelimb forming a wing for flying.

Example 2: Humans: Because humans walk upright, their forelimbs are no longer used to bear weight. Their long upper limbs have carpals, metacarpals, and phalanges that are modified for object manipulation. The shape and angle of articulation of the first digit (the thumb) are particularly noteworthy. This opposable thumb allows for maximum manipulation. These capabilities could not be so specialized if humans were quadrapeds.
Conclusion: Vertebrate Forelimbs (LM page 132)

Vertebrates are descended from a common ancestor, but they are adapted to various ways of life.

Comparison of Vertebrate Embryo (LM pages 132-33)

What does this tell you about their evolutionary relationship? Reptiles are more closely related to birds than fish.
Observation: Vertebrate Embryos (LM page 133)

2. List five similarities of the embryos.

a. General shape of presumptive head

b. Shape and orientation of limb buds

c. Presence and shape of the tail

d. Presence of pharyngeal pouches

e. Placement of the eyes in relationship to the rest of the head

f. Presence and position of yolk stalk
Conclusion: Vertebrate Embryos (LM page 133)

Vertebrate embryos resemble one another because they are related through evolution.
Observation: Chimpanzee and Human Skeletons (LM pages 133–36)

Posture (LM page 133-35)

Table 12.6 Comparison of Chimpanzee and Human Postures

Skeletal Part Chimpanzee Human

1. Head and spine Thrust forward over hips and legs Balanced over hips and legs

2. Spine Short and stiff Long and curved

3. Pelvis Long and narrow Broad and short

4. Femur Straight, no angle Angled between articulations

5. Knee joint Femur about the same size top and Femur larger at bottom

bottom, tibia about the same size Tibia larger at top top and bottom

6. Foot

Opposable toe Yes No

Arch No Yes
2. (Referring to comparison of spines in Table 12.6)): How does this contribute to an erect posture in humans? allows the weight to be balanced above the pelvis

6. (Referring to comparison of foot in Table 12.6): In which animal is the big toe opposable? Chimpanzee How does an opposable toe assist chimpanzees? allows them to grasp tree limbs with feet Which foot has an arch? Human foot How does an arch assist humans? helps them walk erect

7. How does the difference in the position of the foramen magnum, a large opening in the base of the skull for the spinal cord, correlate with the posture and stance of the two organisms? In the human, the foramen magnum is placed almost in the bottom center of the skull; in the chimpanzee, the opening is well to the rear. Humans walk upright, and chimpanzees use all four limbs for walking.
Skull Features (LM page 135)
Table 12.7 Facial Features of Chimpanzees and Humans

Feature Chimpanzee Human

1. Supraorbital ridge More thick Not as thick

2. Saggital crest yes no

3. Slope of frontal bone Slope No slope

4. Teeth Incisors angled, Incisors vertical

canines overlap, canines overlap

molars massive molars smaller

5. Chin Projects Does not project
Conclusion: Chimpanzee and Human Skeletons (LM page 136)

Do your observations show that the skeletal differences between chimpanzees and humans can be related to posture? yes Explain. All changes noted in human skeleton assist in walking erect.

Do your observations show that diet can be related to the facial features of chimpanzees and humans? yes Explain. Chimpanzees eat more plant material than humans, and humans eat more meat than chimpanzees.
Comparison of Extinct Hominid Skulls (LM page 136-38)

Observation: Extinct Hominid Skulls

Tables 12.8, 9, 10 Data will vary according to skulls available and chosen by students.

Conclusions: Extinct Hominid Skulls (page 138)

  • Answers will vary dependent on student observations

12.3 Molecular Evidence (LM pages 138-140)

Why can comparing amino acid data lead to the same conclusions as comparing DNA data? The sequence of bases in DNA determines the sequence of bases in a protein.
Protein Similarity Evidence (LM pages 167–69)

Experimental Procedure: Protein Similarity Evidence

5. Describe what you see. A distinct cloudiness or precipitate forms.

7. At the end of 10 and 20 minutes, record the amount of precipitate in each of the six wells in Figure 12.10.

Conclusions: Protein Similarity Evidence (LM page 169)

The last row of Figure 12.12 tells you that the test serum in well 3 is from a human. How do your test results confirm this? It has the same amount of precipitate as well 6.

Aside from humans, the test sera (supposedly) came from a pig, a monkey, an orangutan, and a chimpanzee. Which is most closely related to humans—the pig or the chimpanzee? chimpanzee

Judging by the amount of precipitate, complete the last row in Figure 12.8 by indicating which serum you believe came from which animal. See above. On what do you base your conclusions? The greater the degree of precipitation, the more similar the animal’s blood serum antigens are to those in human blood serum.

Molecular evidence shows us that of the vertebrates studied, chimpanzees and humans are most closely related.

1. List three types of evidence that various types of organisms are related through common descent. fossil record, comparative anatomy, molecular evidence

2. Why would you not expect a fossil buried millions of years ago to look exactly like a modern-day organism? Evolution has occurred.
3. A horseshoe crab has changed little in approximately 200 million years of existence. Would you expect to find that the environment of the horseshoe crab has changed minimally? Yes. Natural selection of certain changes explains adaptations to new environment.
4. If a characteristic is found in bacteria, fungi, pine trees, snakes, and humans, when did it most likely evolve? In Precambrian time. Why? Each organism inherited the characteristic from a preexisting one.
5. What are homologous structures, and what do they show about relatedness? Homologous structures have similar anatomy because they are derived from a common ancestor. Organisms are related when they have a common ancestor.
6. Why do humans and chicks develop similarly to reptiles? They are related through a common ancestor.
7. What do DNA mutations have to do with amino acid changes in a protein? Mutations are changes in DNA nucleotide base sequences and this sequence determines the sequence of amino acids in a protein.
8. How can antigen-antibody reactions help determine the degree of relatedness between species in this laboratory?. The relatedness of an animal to humans was judged by the degree to which they shared the same antigen-antibody reaction.
9. Using plus (+) symbols, show the amount of reaction you would expect when a pig, monkey, and chimpanzee are tested for the same human antibody-antigen reaction. pig +, monkey ++, chimpanzee +++
10. Define the following types of evidence for evolution:

Fossil: Any past evidence of an organism that has been preserved in the Earth’s crust. Fossils show that organisms have changed (evolved) over time.

Common descent: Descent from a common ancestor. The concept of evolution is based on common descent.

Adaptation: An organism’s modification in structure, function, or behavior suitable to the environment. Differences in adaptations support evolution.

Molecular evidence: Molecules found in organisms such as DNA and ATP. Similarity of these molecules supports evolution.




(LM pages 143–61)

Fourth Edition

No significant changes have been made to this laboratory.

New Figures 13.6 Major Groups of Protists; 13.12 Protozoan diversity

Directory: biosci

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