Establish Prior Knowledge
Call on students to share what they know about the classification of living things. Point out that, in the snapshot students are about to see, organisms are grouped according to cladistics. Cladistics is a system of organizing living things into groups based on shared features also called characteristics. In cladistics, scientists use characteristics to infer an organism’s ancestry. Have students research cladistics at this website and discuss their findings:http://admin.dt-www.amnh.org/amnh2/explore/ology/biodiversity/tree-of-life2
Have students view the snapshot and read the synopsis. Have them pay special attention to the cladogram displayed in the snapshot. Use the following questions to stimulate class discussion:
- What characteristic does this snapshot focus on?
- What areas of the human brain's cortex control this characteristic?
- What other animals have this characteristic and similar areas of the brain?
- Is the Cebus monkey closely related to the Macaque?
- What monkeys are more closely related to the Cebus monkey?
- Do they share the opposable thumb and precision grip characteristic?
Since the Cebus monkey and the Macaque are not closely related, what conclusions can you draw about the evolution of the precision grip and opposable thumb?