Name: ___________________________________________
Period: ____
Evidence of Evolution- Homologous, Analogous, and Vestigial Structures
Objective: To compare homologous, analogous, and vestigial structures and analyze their
significance in evolutionary history.
Part I.
Carefully examine the drawings of the bones in the Figure on the next page. Look for
similarities among the various animals.
1. Color each bone of the human arm a different color. All bones of the wrist (carpals)
should be a single color, and the bone groups of the hand (metacarpals and phalanges)
should be another color. Then color the corresponding bones (containing the same
pattern) in each of the other animals the same color as the human bone (i.e. if you color
the humerus blue in the human, it should be blue in all the other animals).
2. Describe the function of each set of bones below in Table 1:
Table 1
Animal
Human
Whale
Cat
Bat
Bird
Crocodile
3.
Functions
Are the same bones present in each organism?______________________________
4. Are the bones arranged in a similar way in each animal? ______________________
5. What could account for the similarities?_____________________________________
6. What could account for the differences?_____________________________________
7. Explain the differences between the arm of a human and the foreleg of an alligator in
terms of natural selection.________________________________________________________
8. An anatomically similar structure inherited from a common ancestor, as in these
forelimbs, are examples of ____________________________________ structures.
9. Name another example of this type of structure. ____________________________________
Part II.
Examine the butterfly wing and the bird wing shown in Figure 2.
10. What function do these structures share?
____________________________________________
11. How do the structures differ?
______________________________________________________
___________________________________________________________________
___________________________________________________________________
________________________________
12. Do birds and insects share any structural similarities that would suggest
they are closely related? Explain.
___________________________________________________________________
_______________
13. Structures with similar functions, but different constructions, and were
not inherited from a common ancestor are
____________________________________________________ structures.
Part III.
Gradual changes have occurred through time that have, in some cases, reduced or removed
the function of some body structures and organs. The human appendix that is reduced and no longer
digests rough vegetation and pelvic bones of snakes that have no legs are examples of this
phenomenon.
The cave fish and minnow shown in Figure 3 are related, but the cave fish is blind.
14. Explain why eyesight is not an important adaptation to life in a cave.
____________________________________________________________
____________________________________________________________
15. Does the appearance of the cave fish and minnow suggest common
ancestry? Explain.
____________________________________________________________
___________________________________________________________________
16. Organs or structures that have lost their function in the organism and
become reduces in size are called________________________ Structures.
17. Humans also have these kinds of structures. On the table below suggest a
possible function for each structure and reason why it may have become
vestigial. Use the handout labeled CLASS COPY to complete the table.
Table 2
Structure
Appendix
Muscles that
make hair stand
up
Coccyx (tail
bone)
Muscles that
move ears
Wisdom teeth
Possible Function(s)
Why it is considered
vestigial