Academic journal article The American Biology Teacher

Darwin's Error: Using the Story of Pangenesis to Illustrate Aspects of Nature of Science in the Classroom

Academic journal article The American Biology Teacher

Darwin's Error: Using the Story of Pangenesis to Illustrate Aspects of Nature of Science in the Classroom

Article excerpt

Accusing Charles Darwin of making an error is a dangerous strategy for those of us who support natural explanations for change through time. On the one hand, using the work "error" might be seen as heralding an attack on one of the great heroes of biology On the other, there is the strong possibility that those who oppose Darwin and his ideas will read anxiously, looking for support in their ongoing battle with evolution. However, neither alternative will be supported here. While it is true that Darwin made a mistake when proposing a mechanism of inheritance, he remains one of the most productive scientists of all time. So, the purpose of this account is not to criticize Charles Darwin simply for having erred, as if to suggest that truly great scientists never make mistakes. Likewise, those who oppose evolution will find no solace in this account, because the "error" mentioned in the title has nothing to do with Darwin's major contribution of an account for evolution by natural selection. Darwin's many accomplishments--including natural selection--stand as testament to what the human mind can accomplish when inspired by mountains of questions surrounded by a sea of facts.

This article provides a wonderful illustration, rarely included in textbooks, of Darwin working as a scientist to solve a specific problem and interacting with colleagues. As the great evolutionarily biologist and essayist Steven Jay Gould was fond of saying, sometimes errors and mistakes are more revealing than another example of something expected. I began this story in the previous issue of ABT, in which I recounted the fascinating story of Charles Darwin and his invention of a mechanism of inheritance called "pangenesis" (McComas, 2012). Although this story is well known to historians of biology (Geison, 1969; Winther, 2000; Endersby, 2009), it is likely unknown to biology teachers and their students, but it has much to offer because of the lessons it can teach.

Of course, textbooks are not designed primarily as historical accounts but are more like encyclopedias focusing on providing conclusions rather than processes. This leaves naive readers to think that science must be a linear pursuit of the truth without dead ends, conflicts, and the impact of personalities. Such an approach in communicating science is justifiable if the goal is to present as much information as possible while preparing students for the end-of-course exams that focus only on facts and principles. Unfortunately, this picture of science inevitably dehumanizes it while making science less interesting and less accurate if the goal is to present process and product. Rarely do teachers and textbooks show how facts and principles are established by those whose work in the field and laboratory makes its way into the classroom. Here, rather than dwell on the fact of a Darwinian error, I will focus on why the error was made, the reactions of Darwin and his colleagues to pangenesis, and what it can teach us about how science functions. Helping students understand how science is done may open a new avenue of science instruction that communicates the facts while immersing students in the rich historical accounts of the people and processes of science.

Darwin's Hypothesis of Pangenesis

As discussed in more detail previously (McComas, 2012), Darwin recognized two major problems that, if solved, could make his evolutionary mechanism much stronger. These problems were related to the source of new variation and an explanation of the rules of inheritance. Although Darwin was a contemporary of Gregor Mendel, his pea plant experiments were not well known, leaving Darwin with no alternative but to develop his own explanation for inheritance. Furthermore, the production and transmission of new traits--the raw material of natural selection--was a mystery to Victorian naturalists. It is worth pointing out that the twin puzzles of variation and inheritance dogged Darwin throughout his professional life; he was not reluctant to share his frustration with his many correspondents and with his readers. …

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