In this case study, students explore the story of the evolution of lactase persistence based on the short film Making of the Fittest: Got Lactase? The Co-evolution of Genes and Culture and makes connections between genotype, phenotype, and culture using graphical analysis skills.

Lactase persistence, the ability of some human adults to continue to produce the lactase enzyme and digest lactose, is an example of genetic change leading to recent human evolution. Students explore the evidence that demonstrates how mutations leading to lactase persistence have increased in frequency in different populations by natural selection over the last 10,000 years. The case study is designed for introductory biology classes, to engage students in analyzing and interpreting scientific data.

This four-part activity includes watching a film and pausing at specified points to analyze figures and answer questions about lactase persistence and evidence of selection, as well as a summary section to synthesize concepts.