PBS Evolution A Critical Review
Viewers Guide

Activity 2: Darwin and His Finches

Accompanies the Viewer’s Guide, Chapter 1-C, “The Legend of ‘Darwin’s Finches'”


The process of discovery in science is seldom ever neat. Sometimes an idea comes in a sudden flash of insight. Other times it may develop over a long time. Still other times, a scientist may miss an insight because he was looking in the wrong places or because there was a flaw in the way he gathered his data. Unfortunately, popular accounts of science tend to overlook the very human way that even great scientists went about their work. In the pursuit of a compelling story, the storytellers often sweep away all the messiness that can go with real science. Instead of scientists, we are shown heroes and legends.

This is no less true of Darwin than anyone else. It is commonly believed that Darwin’s insight about evolution was sparked by the finches of the Galápagos Islands. But is this how it happened? In this activity, students will read through relevant chapters of The Voyage of the Beagle and The Origin of Species by Charles Darwin, and Darwin: The Life of a Tormented Evolutionist, by science historians Adrian Desmond and James Moore, to determine what helped give Darwin his idea.

Note: This activity has been structured as a research project. If you wish to adapt it to a single class session, you can provide excerpts from Darwin’s work and brief quotes from Desmond’s and Moore’s book.

Learning Objectives

  • Students will understand that scientific discovery is sometimes a messy process.
  • Students will understand that popular accounts of history and science may conflict with scholarly accounts and with the evidence.
  • Students will synthesize material from various sources to determine what factors may have inspired Darwin’s theory of evolution.
  • Students will be aware of the importance of using scholarly sources and original material for verifying popular accounts of history.


Introduce the activity by summarizing the first two paragraphs of the overview. Distribute the readings and worksheet to students and have them work individually or in small groups. After they’ve had time to finish the worksheet, have the class discuss what conclusions they came to.


  • Charles Darwin. On the Origin of Species. 6th ed. (1872). Chapter 13.
  • Charles Darwin. The Voyage of the Beagle. 2nd ed. (1845). Chapter 17.
  • Adrian Desmond and James Moore. Darwin: The Life of a Tormented Evolutionist. New York: W.W. Norton & Company, 1991. Chapters 14-15.
  • Frank J. Sulloway. “Darwin’s Conversion: The Beagle Voyage and Its Aftermath,” Journal of the History of Biology 15 (1982), 1-53.
  • Frank J. Sulloway. “The Legend of Darwin’s Finches.” Nature 303 (1983), 372.
  • Frank J. Sulloway, “Darwin and the Galapagos,” Biological Journal of the Linnean Society 21 (1984), 29-59.

Darwin and His Finches

It is widely believed that Darwin’s theory of evolution was at least partly inspired by the finches he collected while he visited the Galápagos Islands, off the coast of Ecuador. This is the story told in the first episode of the Evolution video series. But is this what really happened?


Using the three books listed at the bottom of this worksheet, try to piece together a picture of what it was that helped inspire Darwin’s theory of evolution. Then answer the two questions below.

  1. What are some of the things that may have helped inspire Darwin’s theory of evolution?
  2. What are the reasons for your conclusions?