Lactase Persistence and Human Migration
How can genetics help us to understand human migration? In this collection, students will use maps, articles, and videos to analyze genetics research about lactase persistence before building their own maps to understand the co-evolution of genes and culture.
This collection can be used in a Biology classroom with units on enzymes, genetics and/or human evolution, in an interdisciplinary unit to link Math with Biology (students to use ratios, statistics, and data to build a map) or in a Geography course.
Students should be either given a color copy of the lactase persistence map or it could be projected. Once students have been given the time and opportunity to look at the map, the following questions should be asked.
- What do you notice about this map?
- What questions do you have about this map?
- What can this map show us about human migration?
Next, ask students to work in groups, each choose one of the following three articles to read, then share a brief summary of their article with those in their group. These articles are excellent resources that provide different perspectives on lactase persistence and evolution. The first article (the source of the lactase persistence map) provides a clear explanation of what we can learn from milk fats found on ancient pottery shards and the link between lactase persistence and migration. The second article focuses on animal domestication and the third on the nutritional benefits of being able to digest lactase as a selective advantage.
The third article also connects lactase persistence, the shift to agricultural communities, and human migration with the genetics of human skin color. This could provide an opportunity for students to discuss the inheritance of skin color and perhaps skin color and race. A separate collection has been made to help discuss this and can be found here.
In the activity section, the Howard Hughes Medical Institute BioInteractive (HHMI) video summarizes some key aspects about the genetics of lactase persistence as well as some of the history. If students have already read and shared out to show understanding, the video could be used to meet the needs of students who tend to be more auditory learners. The activity “Patterns in the Distribution of Lactase Persistence,” also from HHMI, guides students though an understanding of the co-evolution of genes and culture. “Students analyze data obtained from published lactase-persistence studies involving many populations sampled around the world. The activity involves calculating percentages, drawing pie charts, plotting the pie charts on a world map, and analyzing the data. This lesson provides an interdisciplinary approach to studying lactase persistence, connecting biological concepts and data analysis to world geography and culture”. (https://www.biointeractive.org/sites/default/files/Patterns-in-the-Distribution-of-Lactase-Persistence-Educator.pdf)
The map the students create can be compared to the initial image provided (a map of lactase persistence) as well as the information provided by the Smithsonian Magazine articles to predict the path of human migration. Based on the initial map, reading and activity, students can show their understanding of the connection between genetics and human migration by using the Project Zero thinking routine ‘Claim, Support, Question’. Claims can be made based on their new knowledge and then supported with evidence from the map, reading or activity. Then, students can pose questions for further research or discussion.
In the additional resource section, a YouTube clip has been provided to further extend the conversation. Sarah Tishkoff, from the earlier HHMI video, does an excellent job explaining the co-evolution of culture and the gene for lactase persistence.Read More »