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SCIENCE SAFARI TEACHING GUIDE:
The First People

Most scientists believe that modern humans originated in Africa. For decades scientists have discovered incredible finds from different areas of Africa; fragments of bone and human-like fossil remains are giving us tantalizing clues to our past. Ancient rock art created by people who inhabited this land thousands of years ago provides another window into the past. In this episode, Frontiers visits Hilary Deacon and other archaeologists working in South Africa to solve the riddles of human evolution.

 AFRICAN HISTORY & CULTURE ARCHAEOLOGYPALEONTOLOGY ART BIOLOGY evolution natural selection population genetics GENERAL SCIENCE fossils geological time scale prehistoric man MATH ratios SOCIAL STUDIES

Much of our knowledge about early humans is based on inferences. Inferences are "best guesses" that connect an observation with an established fact or association.

Behavioral and anatomical features of early humans are often inferred from partial skeletons or scattered bone fragments. Rarely is an entire skeleton ever discovered by a paleontologist. Sometimes a single bone can be used to uncover a person's or animal's complex biological and social characteristics.

In the following activity, you'll infer a person's height from the length of one bone. By applying a simple calculation to the observed length, you'll develop a "best guess" for body height.

OBJECTIVE

Evaluate mathematical relationships.

MATERIALS

meter stick

PROCEDURE

1. The formulas below illustrate the relationships between bone lengths and a person's height.

MALES (height in inches)

• Height equals (length of radius x 3.3) plus 34
• Height equals (length of humerus x 2.9) plus 27.8

FEMALES (height in inches)

• Height equals (length of radius x 3.3) plus 32
• Height equals (length of humerus x 2.8) plus 28.1

2. Work with a partner. Identify the radius. It is one of the two bones found in the forearm and extends from the base of the wrist to just beneath the elbow hinge. Use a meter stick to measure the length of your partner's radius. Record this length in the table below.

3. Use the formulas to calculate height based on radius length. Record your calculated height in the table below.

4. Now identify the humerus in the upper arm. This bone extends from the shoulder socket to just above the elbow hinge. Use a meter stick to measure the length of your partner's humerus. Record this length in the table below.

5. Use the formulas to calculate height based on humerus length. Record your calculated height in the table below.

6. Use the meter stick to measure your partner's actual height. Record the measured height.

 Bone Length Calculated Height Measured Height RADIUS ` ` ` ` ` ` HUMERUS ` ` ` ` ` `

ANALYSIS

2. Which was a more accurate bone length to base your inference upon? (Answers will vary; however, many students will find it easier to measure the length of the humerus.)

3. Measure the length of your foot. Is this length closer to the length of your radius or humerus? (In most, it will be surprisingly close to the length of the radius.)

EXTENSIONS

• Pool and average the class data collected above. Graph the relationship between radius length and height. Use separate curves for males and females.

• Work with a partner to determine if you can find a correlation between height and the length of a person's tibia, or shinbone. Can you find a correlation between height and the length of a person's femur (thighbone)? Once you arrive at the relationship, have other student groups test out your calculation method.

What are the rituals in your daily life? Do your evening rituals depend on the lineup of sky objects or the lineup of nightly television shows? What can someone learn about you and your society by studying rituals?

OBJECTIVE

Identify and communicate present-day rituals through ancient art techniques.

MATERIALS

• non-toxic finger paints
• paper

PROCEDURE

1. Identify three ritual activities you share with members of your family. Identify three different rituals you share with friends.

2. Obtain a set of non-toxic finger paints from your instructor. Fingerpaint each of the rituals identified above. Use straight lines and the fewest strokes possible to simulate schematic images or the "stick figures" typical of some ancient art.

For more about the South African rock art, see "Rock Art in Southern Africa" in the November 1996 issue of Scientific American magazine.

• In Activity 1, why do the formulas contain different calculations for determining male and female heights? (Skeletons of males and females have different proportions.)

• Do you think archaeologists of the future might interpret the graffiti of today similarly to the way we interpret ancient rock paintings or petroglyphs?

• Much rock art in Paleolithic times in various areas of the world was painted in red or yellow ochre. What is this pigment and why was it used by so many different cultures?

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