Why We Get Sick Card Sort

Activity: Why We Get Sick Card Sort

Activity explanation: In this lesson, students gain an introduction to evolutionary applications in health and disease. Specifically, this lesson focuses on 1) the difference between proximate and ultimate explanations, and 2) six common ultimate explanations for disease, including evolutionary mismatch, coevolution, constraints on natural selection, trade-offs, evolved defenses, and antagonistic pleiotropy.

Learning objectives:

At the end of this activity:

● Students will appreciate the value of an evolutionary perspective in thinking about health and disease.
● Students will be familiar with the breadth of evolutionary questions that exist pertaining to health and disease.

Background information:

The main goal of this lesson is to introduce the idea that evolution can be used to increase our understanding of health and disease, not necessarily to teach evolutionary theory. For this reason, students should come into the lesson with an introductory level background in evolution before this lesson; this lesson is not designed to eliminate common evolutionary misconceptions. A working knowledge of natural selection, mutation, genetic drift, coevolution, and evolutionary trade-offs will be helpful for students.

Implicit in this lesson is that humans are an evolved species. While this lesson does not require knowing details of hominin evolution or the emergence of modern humans, a general understanding of human evolution and human biology, including how modern human environments differ from past evolutionary environments.

Lesson overview:

Activity Description Estimated Time Notes
Preparation for Class
Prepare cards to hand out in class 1. Make one copy of Cards.docx for each group of 3-4 students

2. Cut along dotted lines to create cards

3. Place one set of cards into an envelope that is large enough to hold the cards without folding

4. Add a roll of removable scotch tape to the envelope

About 15 minutes to prepare 10 sets ·  Cards.docx is provided in Supporting File S3.

·  Using a large paper cutter to cut multiple sheets at once saves time, but the cards are narrow and can easily slip.

·  If you have time, students can cut the cards themselves in class; add a small scissors to the envelope.

·  Make sure to tell students to return the tape (and scissors if used) in the envelope at the end of class.

·  Tyvek envelopes are nearly indestructible and can be reused dozens of times.

Class Session
Initial card sort Students sort cards into categories ~15 minutes
  1. Instruct students to open envelope and read through the different cards.
  2. The instructions to students should be actively vague. Tell students to form groups of cards. Each group must have at least two cards in it. Since there are 12 cards, that means that there can be anywhere between 2 and 6 groups they should form. Tell students to create a name for each group.
Lecture with clicker questions Short lecture with clicker questions on proximate vs. ultimate causation, and reasons why we get sick. Suggested slides are available in CardSortSlides.pptx ~15 minutes
  1. Lecture slides for use are included as part of supplemental material.
  2. Lecture slides include notes with suggested material to cover.


Second card sort Students sort cards into categories ~10 minutes
  1. Give students same instructions as initial card sort.
Go over answers Go over suggested groups ~10 minutes
  1. Show students correct sorting according to features based on ‘why we get sick’.
  2. Give time to allow students to compare their groups to the correct groups.
  3. Allow questions and provide an elaboration on each category.
Think-pair-share hypothesis generation Have students work in their groups to generate evolutionary hypotheses and discuss based on slide #X in cardSortSlides.pptx ~5 minutes
  1. Do this as a think-pair-share
  2. Stress to students afterwards that evolutionary hypotheses are hard to test, especially about humans. This is an opportunity to discuss what a “just-so” story is.
Lesson summary Go over what was covered and wrap up main learning goals ~3 minutes


Initial card sort

The goal of the initial card sort is to engage students, not to help them get the correct answer. Card sorting activities, including this one, are designed so the cards themselves have shared surface level features as well as shared deeper level features. This initial card sort should be thought of as an engaging pre-test for students.

Hand out an envelope for every three or so students who will work on this activity as a group. Once students all have their envelope of cards, instruct them to open the cards. Explain to them that their task is to sort these cards into distinct groups. The only rule they have is that each group must have at least two cards (that is, no card can be in a group by itself), and that once they have determined their groups, they should give their group a name.

Once the students start working, circulate the room and ask students about their thought process for making groups. This will give you an idea whether students see the deeper level features (the reasons why we get sick), or if they are instead sorting on surface features of the cards. Give them about 10 minutes to work on this task.

Lecture with clicker questions

After students have completed their card sort, you will go through a short lecture with clicker questions to teach students the difference between ultimate and proximate causation, as well as six common reasons why we get sick. This part of the lesson should allow students to practice identifying proximate and ultimate reasoning for traits, and then instruct them on the common reasons ‘why we get sick.’

Second card sort

Students should be instructed to sort the same cards again with their group. The rules for this second card sort will be the same as the first card sort – each group must have at least two cards (no card can be alone in its own group), and each grouping needs a name. Do not prompt them to look for the deeper connection in the cards, as they should hopefully be able to start seeing this connection on their own.

Go over answers

Take time to go through the expert-level categories and the connections between the cards. This is a great opportunity for students to ask questions and challenge the answer key. This time can be used productively by talking through potentially different ways of sorting, and how ultimate explanations do not have to be mutually exclusive from one another.

Think-pair-share hypothesis generation

The last part of this activity is to allow students to generate their own evolutionary hypotheses for several traits. Have them do this as a think-pair-share activity. First have them think to themselves for about a minute and generate their own ultimate hypothesis. Then have them share their thoughts with their neighbor and discuss their hypotheses. Lastly, have them share out their thoughts.

This will offer an opportunity to discuss aspects of the nature of science, including what is a hypothesis. As the instructor, you should have students think about whether or not they can know if their hypothesis is correct. Prompt the students to discuss with their neighbors whether their hypotheses are correct or not, and ask them to start discussing how they could potentially test them. End this section by discussing some of the difficulties in testing evolutionary hypotheses, which is a large part of what occurs in evolutionary medicine research.

Lesson summary

Go over the last slide that summarizes the goals of this lesson.