Biology 12

Chapter 15 Human Ecology • MHR 531

as desired. The number of red pebbles drawn does

not matter.

6.After all members of the community have drawn

once, the number of white pebbles remaining in the

bag are counted. Add the same number of white

pebbles to the existing pebbles and place all of

them back into the bag (that is, double the number

of white pebbles in the bag). Leave all existing red

pebbles in the bag.

7.Repeat steps 1 through 6. The completion of two

rounds represents the first generation.

8.Repeat steps 1 through 6 for two more rounds.

During these rounds, three red pebbles must be

placed in the bag for each white pebble drawn.

Rounds 3 and 4 represent the next generation —

the children of those community members who

started sharing the original land (white pebble)

parcels.

9.Repeat steps 1 through 6 for two more rounds.

Place three red pebbles in the bag for each white

one drawn during this round as well. Rounds 5

and 6 represent the third generation — the

grandchildren of the original community members.

Post-lab Questions

1.How many members of the community were forced

out of the game during the first generation? in the

second and third generations?

2.Why did each community member take as many

pebbles as he or she did? (Each member should

explain his/her reasoning to the other community

members.)

3.Did any member of the community have an

advantage over others? Explain your answer.

Conclude and Apply

4.How did the actions of the first generation affect the

third generation? Do you consider this fair? Explain

your answer.

5.Why did players increase the number of red pebbles

added during Rounds 2 and 3? Is this a reasonable

representation of what might take place in nature?

Exploring Further

6.Play the game again, this time without using the

bags so that members of the community can

monitor the condition of the shared resource and

the amount of pollution being added. Does this

change the length of survival time for all members of

the community? Was it possible for any community

to sustain the resource so the pollution levels were

the same in the third generation as in the first? How

much communication among community members

was necessary to sustain the resource?

health, especially if they affect sources of drinking
water. This is also true of disease-causing organisms,
which can be considered another form of pollution.
These can include the bacteria, protists, or viruses
that cause a diverse array of illnesses such as
typhoid fever, cholera, and hepatitis. For example,
Escherichia coli(various forms of which cause
diverse illnesses), Giardia, and Cryptosporidumare
organisms that commonly pollute water in areas
where sewage treatment is inadequate or animal
wastes can infect water supplies.
The following investigation will give you a
chance to learn how resources can be adversely
affected if not managed in a sustainable way.

Figure 15.21Although there is a lot of biological activity

going on in this pond, it is not a healthy place for animals.