Darwin's description of his epochal work as “one long argument” in the opening line of the book's final chapter has long served as a general guide to the way in which Darwin conceptualized his theory, but the fuller picture of Darwin's creative process was possible only as his correspondence, notebooks, and other private writings became available for study (Eldredge 2005).Considered from our vantage point 150 years after the 's publication in 1859, telescoped by time, it is often unappreciated that key elements of Darwin's thinking unfolded over a dozen or more years—with even his central mechanism of species sersification, his “principle of sergence,” not coming to him until well into the 1850s.Darwin scholars have long appreciated this, of course (e.g., Hodge 1977, 1992, Kohn 1980, Mayr 1991, Browne 1995, Waters 2003), just as they have seen Darwin's post- in the form of explorations and applications of his theory.
As with Darwin's breeders, it is instructive for the rest of us to analyze how he got there to better appreciate the process.Students of evolutionary biology at all levels would profit from better understanding Darwin's intellectual odyssey and mode of investigation, with its interplay of the inductive and deductive, and historical methodology.The double Darwin anniversary of 2009 thus presents an opportunity not only to celebrate Darwin's achievements but also, in appreciating the development of these ideas, to consider how we might learn from his approach in the way we teach evolution today.Darwin may have believed in species fixity throughout the voyage (Sulloway 1982a, 1982b), but during this period he reflected on the nature of species and the meaning of their geographical distributions, particularly in the voyage's final year.The idea of evolution by natural selection formulated by Charles Darwin and Alfred Russel Wallace is a cornerstone of modern biology, yet few biology students or professionals are familiar with the processes of discovery behind the idea.
Focusing on Darwin, I draw on letters, notebooks, and other resources to trace key insights and put them into historical context, illustrating how major elements of Darwin's theory came to him over many years.
I further consider how Darwin came to formulate the logical argument structure of hisdiscussing the philosophical arguments inherent in the book's structure and how this and Darwin's other works can be seen as part of a larger argument and way of looking at the world.
I suggest that in teaching evolution today, educators could profitably draw on both Darwin's personal intellectual journey in coming to his ideas, and the compelling argument structure he devised in presenting his theory Deep in the opening chapter of On the Origin of Species is a passage that has always struck me as having a slightly exasperated tone: Seemingly frustrated with animal breeders' unwillingness or inability to see that they create their remarkably sergent breeds gradually through a process of selection, Darwin laments that breeders “refuse to sum up in their minds slight differences accumulated through many generations” (Darwin CR 1859, p. Appreciating the slow and stepwise nature of change under domestication is central to understanding the natural process of species change, Darwin argues.
A focus on the end product by these breeders is understandable, given the slow process of change.
There is a similar tendency to focus on the end product in the realm of ideas, including the fruitful products of Darwin's own thinking.
The idea of evolution by natural selection, a central pillar of the biological sciences, might be too easily perceived by modern readers as a monolithic idea grasped more or less at once by Darwin.