Our study of evolution turns to an investigation of the enzyme lactase, which converts lactose (a sugar found in milk) into the sugars glucose and galactose. While lactase is found in the digestive system of infants, many adults no longer express the enzyme and thus suffer from lactose intolerance. However, there are populations of people in the world who continue to express lactase as adults. Such people are called lactase persistent. People who no longer produce lactase are called lactase nonpersistent (or more commonly, lactose intolerant). Today and tomorrow, students will investigate which populations of people around the world have developed lactase persistence, and they will analyze data and use their analysis to write a conclusion based on the Cultural-Historical Hypothesis. We will make use of a set of materials collected from a much larger body of work published by BSCS. We will also use the Complete Map of Test Results to complement the mapping work students will do using data from 70 different test subjects.
Note: the conclusion writing assignment is due Monday, March 5.
We will begin the lesson by watching the HHMI video Got Lactase? The Co-Evolution of Genes and Culture provided below: