Who were your ancestors? Genealogy is a fascinating hobby for many people. Perhaps you heard your grandmother talk about her grandparents. If so, you may know more about your great great grandparents than most people. Sometimes family bibles will take records back a century or two - a few names, birth and death dates, and place of birth. That’s not much but you can be pretty sure the people mentioned had arms, walked upright, and breathed air. You would be hard pressed to find out hair color, eye color, intelligence, height, weight, and personalities of your ancestors only a few generations back. Alex Haley's hit book and TV series Roots traced an African-American family back 10 generations to Africa. This case study asks you to think of your ancestors in some cases more than a hundred million generations ago!
How much of your genealogy can you fill in? Can you trace the source of your mitochondria?
A.
The table that
follows lists 13 anatomical, behavioral, or physiological
characteristics of
different groups of living organisms that are not characteristics of
humans.
However, they are characteristics that may have been possessed by
distant human
ancestors. Examine the list and individually
without discussion consider
each characteristic as a separate hypothesis about your own distant
ancestry.
B.
Without worrying
about evidence for the moment, fill in your position on each hypothesis
-
agree, disagree, or uncertain. In the final column, write a brief
justification
for your position. If you are uncertain of the meaning of a word, look
it up in
the dictionary available in the classroom.
C.
In the final column,
write a brief justification for your position. When you are done, raise
your
hand to be put in a group. Note: This will be a temporary group for
today and
next period.
Non-human Characteristic (Hypothesis) |
Results from initial responses |
|
||
|
|
|
||
1. Unicellular | ||||
2. Aquatic | ||||
3. Had a prehensile tail | ||||
4. Had scales | ||||
5. Photosynthetic | ||||
6. Anaerobic | ||||
7. Knuckle walker | ||||
8. Egg laying | ||||
9. Asexual | ||||
10. Winged | ||||
11. Had a chitinous exoskeleton | ||||
12. Arboreal | ||||
13. Fossorial |
A.
When the group
first forms and before it has any discussion on human ancestry,
summarize the
initial positions of all group members by entering the totals in each
category.
Do not try to reach consensus or argue your
position at this point.
B.
Discuss those hypotheses
that lack group consensus or show the greatest amount of uncertainty.
See if
the group can reach consensus, agree or disagree, on each hypothesis.
C.
At the end of
class,
turn in the group's table. Indicate whether the discussion
moved the
group toward consensus on the hypotheses having initial disagreement or
uncertainty. Also indicate in the
margin, who will be investigating
each disputed or unresolved hypothesis and reporting on it next period. (One hypothesis per student.)
A. At the end of class (2/6), identify
those
hypotheses that lack consensus and distribute them among the group
members
trying to match hypotheses with individual interests. Using resources
available
in the Morris Library and on the Internet, find out as much as you can
about your hypothesis and be prepared to present a logical argument
based
on data supporting or refuting it.
B. Each group will present
what they found out about possible characteristics of distant human
ancestry.
Based on your discussions in class and further research as necessary, write a ~1-2 page argument based on evidence (provide references) that agrees, disagrees, or confirms uncertainty. Your findings will contribute to class discussion.