This activity explores the content and research presented in the short film The Making of the Fittest: Got Lactase? The Co-evolution of Genes and Culture, which describes a case of recent human evolution influenced by cultural factors.

Babies can easily digest milk, the food especially provided for them by their mothers. Later in life, most of us lose this ability because we stop producing lactase, the enzyme that helps us digest the sugar in milk. But about one-third of adults worldwide continue to produce the enzyme, a phenomenon known as lactase persistence. This film explores the genetics behind lactase persistence and discusses research that traces the origin of this trait to less than 10,000 years ago. The origin of lactase persistence coincides with a cultural shift in human populations who began to use the milk of other mammals as food. Combining genetics, chemistry, and anthropology, this story provides a compelling example of the coevolution of human gene regulation and human culture.

The “Student Handout” probes students’ understanding of the key concepts addressed in the film. The “Educator Materials” document provides suggested pause points in the film with questions for students, background information, and detailed discussion points; a list of related resources and references; and an answer key for the “Student Handout.”