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Keeping the Peace

Chimp Manners

Monkey See, Monkey Do?

Chimps Count

Finger Food

The Mating Game
in the classroom

PRIME-TIME PRIMATES: Keeping the Peace

Do primates share? Is aggression a natural tendency, determined by our genes? Primatologists Frans de Waal and Peter Judge are challenging many assumptions in their work with chimpanzees and capuchin monkeys at the Yerkes Primate Center at Emory University in Atlanta. De Waal sees evidence for cooperation and peacemaking among nonhuman primates, and Judge is finding that, contrary to earlier studies with rats, overcrowding produces coping behaviors.

Curriculum Links
Activity 1: Impact of Overcrowding
Activity 2: Cooperative Games
Think About It!



ethology, Rh factor

brain chemistry,



animal kingdom,
experimental method

adaptation, genetics

probability, statistics

coping skills,
social behavior


When a species loses its natural space, how does it affect the individual? Primates from humans to aye-ayes are feeling the pinch of overcrowding. Yet while humans sometimes elect to live in a crowded situation, animals suffering from habitat loss or other events do not usually choose to be placed in that environment. This game demonstrates what happens as a population loses its space. To play, you need a 100-foot-long rope and an open space. Any number of people can play.

  1. Make a circle on the ground with the rope.

  2. With your classmates, pretend you are rhesus macaques (or rabbits or another animal).

  3. Stand inside the rope circle. This is the total area you have for your living space. You cannot live outside of the rope.

  4. One at a time, your teacher or a designated class leader will announce an event that impacts the living space (events are listed below). With each event, you should make the rope circle half the size that it was.

  5. Allow a minute to get used to your new living situation, as the area shrinks each time.

  6. Depending on the number of players, you may not be able to introduce all five changes before the monkeys run out of room and begin to fall out of the circle.

  7. As soon as monkeys start to fall out of the circle, stop the activity and discuss what happened.

  • Fire destroys half of the living area.
  • New houses are built, covering half of the living area.
  • A heavy storm floods half of the living area.
  • A new road is built that covers half of the living area.
  • Forests are razed and removed from half of the living area.

  1. How did you feel as the space became more limited?

  2. Do you think this happens in real life? Give an example.

  3. What could be changed to make the outcome different?


Social groups, whether composed of human or nonhuman primates, develop cooperative systems to share resources. Sometimes the systems are successful, and everyone has enough. Sometimes the systems fail, and some members will not have enough. How do groups develop systems of cooperation and reciprocity? What happens when there's not enough to go around? Through these games, you will explore the benefits of sharing food and find out what happens when the system breaks down. Then you will figure out how to fix it -- and apply your solutions to problems in the real world.


  1. Each student needs two pieces of paper. For the first round of the game, students should write the letter "R" or "G" on one piece of paper (no one should see the letter).

  2. The teacher or designated activity leader should understand the scoring system, but should not share it with the class. The system works like this: if a student writes "R," s/he gets two food points; no one else gets any points. If a student writes "G," everyone except that student receives one point; s/he gets none.

  3. After students write their letter, the teacher or activity leader should go around the class and ask each student which letter s/he chose. The leader will announce the letter and award points according to the scoring system. Students should keep a running tally of their points as results are announced.

  4. What happens? Discuss the results.

  5. Try the game a second time; this time, the leader should tell students that "R" stands for receive and "G" for give.

  6. What happens this time? Does anyone choose different letters? Discuss the results.

TE Note: Students should discover that if they all write "G," they will actually receive more food points than if they all write "R."


  • 10 poker chips or bingo markers for each student
  • bag of candy, enough for two pieces each

  1. Divide the class into groups of 8 to 10 students.

  2. Groups should sit in a circle in which each student is at least three feet from the center.

  3. Multiply the number of students in your group by ten and then divide that number by four. Place that number of chips in the center of the circle. (For example, if there are 10 students in the group: 10 students times 10 chips equals 100 chips divided by 4 equals 25 chips.)

  4. Make sure everyone understands the rules of the game (see rules below).

  5. Repeat several rounds. The center pool of chips will probably be depleted the first time you try the activity. See if you can figure out how sharing will enable the resources in the center pool to go further, then try the game again.

  1. Is there a way that everyone can get a piece of candy? How?

  2. Can you give an example of this kind of sharing in the real world?

  3. Can you give an example of food transfers among people similar to those practiced by the monkeys seen on Frontiers?

  • The chips belong to the entire group.

  • When the teacher or class leader says "go," everyone may take chips out of the pool in the center.

  • You may trade in ten chips for a piece of candy.

  • When the leader says "stop," everyone stops and sits still.

  • The leader then doubles the number of chips left in the center pool, but never increases the number of chips to more than the original amount in the center pool.

  • After chips have been added to the center pool, begin another round.

  • You may not talk to anyone during the game.

These cooperative games activities were adapted by permission from "For Earth's Sake - Lessons in Population and the Environment," by Zero Population Growth, 1400 16th St. NW, Suite 320, Washington, DC 20036.

  • Would you agree with primatologist Frans de Waal that peacemaking and cooperation are instinctive behaviors among primates? Do you think his theories apply to all primates?

  • How do you account for the rise of violence and aggression in society? Do you think the causes lie in our genes, pressures from the environment, or a combination of both?

  • What kinds of "coping strategies and behaviors" do you observe among people in modern society?

  • Do you think the monkeys seen on Frontiers share food because they are naturally generous, or because they've developed a system of mutual cooperation from which they all will benefit?

  • Can you find parallels in human society to monkey society? For example, what are some ways a leader or dominant personality maintains a hierarchy? How do people share food (or other resources) and what do they expect to gain from sharing?


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.