An introduction to EvMed

Activity: An Introduction to EvMed

Aim: Understanding the basic principles of evolutionary medicine

Level: This lesson could be used in introductory college biology or evolution classes

Prerequisite knowledge for students: Basic understanding of evolution

Time: This lesson is intended to take approximately 50 minutes

Guiding Questions:
• How can evolutionary medicine be used to understand medical conditions?

Learning Objectives:
After completing the lesson, students will be able to:
• Understand the difference between a proximate and ultimate cause of disease
• Understand the six reasons for vulnerabilities to disease

Background information:
Evolutionary medicine is a growing field that aims to apply evolutionary principles to the progress of medicine. Medical research traditionally offers proximate or mechanistic explanations of disease, explaining how we get sick. In contrast, evolutionary medicine seeks ultimate explanations, or seeks answers to why we are vulnerable to different disease in the first place.

This lesson is designed to introduce students to basic principles of evolutionary medicine, and apply these to clinically relevant examples.

This lesson first focuses on teaching the difference between proximate and ultimate explanations. The other principles introduced in this activity are six commonly cited ultimate explanations for disease, which can be explained by evolution. These are:

1. Pathogens coevolve with hosts.
2. Evolutionary mismatch with modern environments.
3. Constraints on what evolution can do.
4. Trade-offs between traits.
5. The fact that evolution selects for reproduction, sometimes at the expense of health.
6. Many evolved traits that are helpful result in some amount of pain or suffering (e.g. fevers).

Suggested Outline:

  • Before class
    • Prereading (15 minutes)
  • In class
    • Introductory lecture (15 minutes)
    • Activity and jigsaw (25 minutes)
    • Debrief lecture (10 minutes)
  • After class
    • Post-quiz (10 minutes)

Materials:
Prereading – Nesse and Dawkins
Slideshow (Contains both introduction and debrief)
Worksheet for student (1 per student in the class)
Clinical Briefs (Print enough briefs so each student has 2 and an equal number of each brief)
• Lower Back Pain, Eric R. Castillo and Daniel E. Lieberman
EMPH 2015: 2-3 doi:10.1093/emph/eou034
• Fever, Elspeth V. Best and Mark D. Schwartz
EMPH 2014: 92 doi:10.1093/emph/eou014
• SIDS and Infant Sleep Ecology, Helen L. Ball and Charlotte K. Russell
EMPH 2014: 146 doi:10.1093/emph/eou023
• Inflammatory Bowel Disease, Shona J. Lee and Rick M. Maizels
EMPH 2014: 95 doi:10.1093/emph/eou017
• Gastrointestinal Dysbiosis, Daniel T. Blumstein, Karen Levy, Emeran Mayer, and John Harte
EMPH 2014: 163 doi:10.1093/emph/eou029
Post-quiz

Prereading
The prereading should be completed by students prior to the in-class activity. This is a short excerpt from the Oxford Textbook of Medicine, 5th edition that nicely summarizes the relevance of evolution to medicine. It also covers the six kinds of evolutionary explanations for vulnerability, a key concept in this lesson. The writing level is appropriate for a college student and it should take approximately 15 minutes to read.

Introductory slideshow
The provided PowerPoint slideshow is intended both to go over material from the prereading, including two key concepts in evolutionary medicine: the difference between proximate and ultimate explanations and the six reasons for vulnerabilities to disease. Students will be prepared to complete the jigsaw activity after completion of the introductory slideshow.

The slideshow includes clicker questions. We highly recommend that instructors follow the structure of peer instruction (cit Mazur – other guides that may be local to our webpage) when asking clicker questions:
1) Initially read out the clicker question, and offer students the chance to think and answer individually.
2) Allow students to talk in pairs or small groups and answer the clicker question again.
3) After revealing the answer, explain why the correct answer is correct and why incorrect answers are incorrect.

See the slideshow notes for notes on clicker questions.

Activity

The activity consists of the students reading and answering questions about two clinical briefs in pairs. These questions walk the students through thinking about the proximate and ultimate causes of the conditions discussed in the brief and ask them to critically analyze claims made in the briefs. The students are also asked to consider the six evolutionary explanations for vulnerability to disease.

Jigsaw

After completing the activity, the students will “jigsaw” and share their findings with another group of students who completed the activity with a different set of briefs. There is a set of guiding questions to complete to ensure that the students are discussing proximate and ultimate causes.

Debrief

The debrief slides offers a set of deeper questions for students to consider in small groups or as a class. Notes about discussion can be found in the slideshow notes.

Post-quiz

This is a short, 6-question quiz meant to re-emphasize points brought up in the lesson.

Answer key:
1. D
2. A
3. B
4. D
5. B
6. D