Accessing the Debate of Modern Human Origins: Modeling the Mitochondrial Clock
Teacher Background Information:
The attached description for students should reasonably address the use of this particular activity in a human evolution class as the "Out of Africa" vs. "Multi-Regional Evolution" debate is addressed. It is genuinely difficult for students to understand the concept of molecular clocks, and how the accumulation of mutations reflect the length of time two populations (or two species) have been geographically or reproductively separated from one another.
The materials used may be any plastic tiles. (The 1"X 1" rainbow tiles used in mathematics work fine, but even cut file cards work well.) Thirty tiles are numbered 1-30 and are placed in an opaque container so the numbers may be drawn randomly. For each "population" you will ultimately isolate you will need an opaque "drawing" bag and four differently colored tiles, one each marked with the letters A, C, G, and T for the nucleotide base pairs. Make all A's the same color, all T's another color, etc.
Preparation of the materials, including photocopying of the activity sheet should take under an hour. The activity itself can be accomplished in one 45 minute period, including discussion of preliminary observations of the process of "mutation". Follow-up discussion takes a similar length of time.
Student Introduction | Student Worksheet