Name Class Date Activity: Comparison of Primates Background Information: In the 19th century, English naturalist Charles Darwin startled the scientific community by announcing his hypothesis: Humans and primates, such as the apes, evolved from a common ancestor. In Darwin’s time, many people criticized his ideas about evolution. Today, scientists know that primates and humans share many identical amino acids in their DNA sequence, supporting Darwin. In this activity you will measure and analyze structural differences between humans and their relatives. Darwin observed that traits among human beings and other primates differ in many ways. These differences include cranium size (skull), skeletal structure and hand movement. Objectives: To observe, compare and measure several characteristics of primates. To infer the identity of primates based on observations and comparisons. Materials: Masking tape, ruler. Procedure: Part A 1. First carry out every activity in Data Table 1 using your thumb. For example, as your partner observes, write your name, class period and date in the space provided. Write a check mark in the “Using Thumb” column. Do the same for each activity you complete. 2. Ask your partner to tape the thumb of your writing hand securely to your index finger and repeat the activities. Your partner will place a zero (0) in the “Without Thumb” column if you have difficulty with the task. 3. Remove the tape from your thumb and trade places with your partner and repeat steps 1 and 2. Data Table1: Observations of Simple Activities Activity Using Thumb Without Using Thumb Write name Tie shoelace Remove and replace watch “check” = easily completed “0” = done with difficulty Work Space: Part B: 1. Look at the illustrations in Figure 1 of the hands of some primates. Write your observations as to the type of thumb, palms, and fingers in Data Table 2. Then describe some possible adaptations suited for each type of hand. 2. Examine the illustrations of the skulls in Figure 2. Note the relative sizes of the jaw and the degree each one juts forward away from the face. Record your observations in Data Table 3. 1 3. Note the relative sizes of the skulls in Figure 2. Measure the length and width of the rectangle in millimeters and calculate the area (A = L x W). 4. Examine the illustrations of skeletons in Figure 3. The primates are shown from the front and the side. Write your observations in Data Table 4. Data Table 2: Observation of Primate Hands Primate Unique Feature Tarsier Large pads Baboon Orangutan Gorilla Human Data Table 3: Comparison of Primate Skulls Feature Skull A Size of Jaw Largest Angle of Jaw Large, greater than 90 Calculated Area: for brain (A=LxW) Possible Adaptation To climb on tree trunks Skull B Skull C Data Table 4: Comparison of Primate Skeletons (choose from words in italics) Feature Skeleton A Skeleton B Vertebral Column (spine) -curved/ straight Shape of Pelvis -bowl shaped/narrow Relative length of arms to legs -arms shorter than legs - arms equal to legs Bipedal (uses two feet to walk) or Quadriped (uses arms and legs to walk) Position of Skull - over spine/not over spine Applying Your Knowledge: 1. Explain the advantage of having a thumb. 2. Place the three primate skulls in order from the smallest jaw to the largest. Explain how you can infer the identity of the primate with the largest jaw. 2 3. Make a statement comparing the size of the brain (area) and jaws for the three primate skulls. Explain how you think this fits into the evolutionary scheme of primates. Summary: Write a three paragraph summary using our standard format (what you were doing in this activity and why, what you found out by doing this activity, and how this information relates to your life). 3