PBS Evolution A Critical Review
Viewers Guide

Activity 4: The Centrality of Evolution

Accompanies the Viewer’s Guide, Conclusion, Section D, “Is Evolution Indispensable to Medicine, Agriculture, and Choice of Mate?”


In a 1973 article in The American Biology Teacher, geneticist Theodosius Dobzhansky made the now-famous statement that “nothing in biology makes sense except in the light of evolution.” This theme appears throughout the Evolution video series, which portrays Darwin’s theory of evolution as central to both medicine and agriculture.

Yet even some scientists friendly to this message think Dobzhansky may have overstated his case. Molecular biologist Bruce R. Levin, for example, has noted, “While evolution may well be the thread that ties all of biology together, concern about the fabric of the subject seems to have had little play in much of modern biology. There are professional biologists who would be indifferent to the . . substance of Theodosius Dobzhansky’s 1973 essay. . . . Indeed, as I found the other day, when speaking with a bright, and not-that-young, molecular geneticist, there are biologists out there who have never heard of Professor Dobzhansky. One can be a successful practitioner of many areas of contemporary biology without considering how organisms, molecules or phenomena came to be or their descent relationships. A relative absence of interest in evolution prevails in a number of areas of biology, with high-tech molecular biology being the most prominent among them.”1

In a similar vein, Peter Grant, whose landmark work on the Galápagos finches was featured in Jonathan Weiner’s Pulitzer Prize-winning book, The Beak of the Finch, stated in his 1999 presidential address to the American Society of Naturalists, “Not all biologists who would call themselves naturalists pay attention to [Dobzhansky’s maxim] or even feel the need to. For example, an ecologist’s world can make perfect sense, in the short term at least, in the absence of evolutionary considerations.”2

Just how important is Darwin’s theory of evolution to such areas as agriculture and medicine? One way to find out is to ask practitioners in each field what they think. In this activity, students will interview farmers or physicians to discover their views on how important Darwin’s theory is to their work.

Note: In this activity students will be constructing and administering a questionnaire. Make sure students understand that they are not conducting a scientific survey. Although the survey may tell students what their respondents think about evolution’s centrality, it won’t necessarily tell them what doctors and farmers as a whole think.

Learning Objective

  • Students will know how some farmers or doctors in their community view the importance of evolution to their work.

Directions (will require multiple class sessions)

Introduce this activity by referring to those segments of the series that talk about the importance of evolution for agriculture and medicine. (Those segments include Episode One on HIV; Episode Three on leafy spurge; Episode Four on tuberculosis and cholera; and Episode Six on diabetes — though you may only want to refer to those segments that they have already seen.) Tell the class that they are going to investigate what doctors or farmers think about the importance of evolution to their work. They are going to do this by creating a brief, informal questionnaire and then using it to interview the doctors or farmers.

Take the students through the following steps (spread these steps over as many class periods as you need):

  1. Decide with the class whether they will interview doctors or farmers or both. (To keep the task of designing a questionnaire as simple as possible, it is recommended that you choose either doctors or farmers rather than both.) When you pick a group, make sure that there are enough so that each student can interview one person.
  2. Brainstorm some questions for the questionnaire. A good questionnaire will take “multiple routes” to get to the same information. Try to come up with three to five different questions that get at the information you need. Below are some sample questions for doctors that ask about the importance of evolution in different ways:
    • In medical school, how many classes did you take on evolution?
    • In medical school, how much was evolution integrated into your classes?
    • How would your practice of medicine be different if you were unaware of Darwin’s theory of evolution?
    • How much of a role does Darwin’s theory of evolution play in your work?
    • On a scale of 1 to 5, with 1 being unimportant, 3 being moderately important, and 5 being extremely important, rate the importance of evolution to your practice of medicine.
UnimportantModerately ImportantExtremely Important
  1. Agree on single set of procedures for administering the questionnaire. Will you administer the questionnaire by phone or in person? How will the students introduce themselves and explain what they’re doing? Should students formulate a script to read?
  2. Assign a student to assemble the questions and procedural instructions into a single form.
  3. Decide with the class how they will identify and select people to interview. Make sure that whatever procedure you choose guarantees that no respondent will be approached by more than one student. Since this isn’t a scientific survey, don’t worry about trying to obtain a random survey. Also, be sure to assign each student more than one person to interview, because not all respondents will be willing or able to be interviewed.
  4. Assign one or more students to compile a list of respondents who will be interviewed by students.
  5. When the questionnaire form and respondent list are completed, pass out the forms and assign each student some people to interview.
  6. After the students have had time to complete their interviews, tally the responses to each question in class and discuss the class’s findings. Possible questions to ask include:
    • What do the results of the interviews say about the importance of evolution for medicine/agriculture? Explain your answer.
    • For those who said that evolution is unimportant, is it likely that they were simply unaware of how evolution affects their work? Why or why not?
    • If we can look in such fields as medicine or agriculture and find examples of natural selection, does that mean evolution is vital to that field? Why or why not?


  1. Bruce R. Levin, “Science as a Way of Knowing — Molecular Evolution.” American Zoologist 24 (1984), 541-464.
  2. Peter R. Grant, “What Does It Mean to Be a Naturalist at the End of the Twentieth Century?” The American Naturalist 155 (2000), 1-12.