Spanish versions of these resources are also available for download (en Español).
Skin color is a polygenic trait. In Part 1 of this activity, a simple mathematical model illustrates an idealized relationship between the number of genes involved in a trait and the number of phenotypes derived from the combination of alleles. In Part 2, students learn about the methods by which geneticists identify skin-color genes and estimate heritability. Finally, in Part 3, students learn how geneticists analyze genetic variations to trace an individual’s ancestry. Students draw conclusions about the predominant ancestry of two different individuals by comparing their genetic profiles against real allele frequency data.
This activity was designed to be completed after watching The Biology of Skin Color. It should be able to be completed within a single 50-minute class period but may take longer depending on the amount of class discussion. This timing does not include the 20 minutes necessary to watch the short film.