I recently completed reading one of the most stimulating books (1) on the conceptual aspects of evolution that I have read in many years. The author, Peter Godfrey-Smith is a philosopher of biology at Harvard. He has written widely on topics in the philosophy of science and is the author previously of an exceptionally thoughtful introduction (2) to that field.
The new book is intended both to clarify philosophical thinking about concepts central to evolutionary theory and to advance biological understanding of the processes of evolution. Godfrey-Smith also proposes as an objective of the book, if I can do his precise wording justice in abbreviated form, the implications of evolutionary science for broader questions of interest to philosophers, scientists, and perhaps others.
In the course of his disquisition, which I found fair-minded and often incisive, Godfrey-Smith addresses numerous topics that should be of interest to evolutionists and to devotees of evolutionary medicine. I hope a small sampling of subjects and associated insights should provide a sense of the depth of his discussion.
The author explores (in Chapter 2) the various proposed formulations that have been used to encapsulate the essence of the mechanism of evolution (e.g., heritable variation that influences reproductive output leads to evolutionary change). He shows why most such formulations are flawed and how they would need to be amended. Throughout, he is explicit about the trade-offs between concision and accuracy and the different imperatives for one versus the other. Among the key points that Godfrey-Smith makes is that evolution and selection are not synonymous and that there are conditions where each can occur without the other. He also offers a pointed critique of the gene-centric approach to evolution.
In Chapter 3, Godfrey-Smith also methodically demonstrates the importance of recognizing that in any exploration of key evolutionary concepts that it can be important to take note of both paradigmatic and more marginal cases. So, for instance, in discussing what he refers to as Darwinian processes, he analyzes examples that vary in a multi-dimensional space created by permitting variation in the fidelity of heredity, the dependence of realized fitness differences on intrinsic properties, and the continuity (or smoothness) of the fitness landscape (i.e., the dependence of realized fitness on organismal attributes). Other population-related characteristics that are included in his overall discussion are the abundance of variation and the nature of the influence of competitive interactions on the magnitude of reproduction. Although this entire discussion is abstract and may be challenging, it addresses important issues that are bound to arise in the efforts to understand phenomena associated with real populations.
Godfrey Smith discusses, in Chapter 4, nuances and complexities of the evolutionarily pivotal concept of reproduction. He addresses such issues as the sometimes fuzzy boundary between reproduction and growth, the appearance of new, or apparently new, individuals without it being obvious that one can identify specific parental organisms, the distinction between the “evolutionary individual” and the “physiological individual,” and the semantic and conceptual difficulties likely to be encountered in trying to clearly describe reproduction of collective entities such as herds or “colonial” organisms (e.g., some green algae or corals).
The remaining chapters (of eight total) examine some of the topics already mentioned (i.e., reproduction and the gene-centered view of evolution) in greater depth or from a slightly different angle. In addition, new topics (individual versus group selection and cultural evolution) are carefully dissected.
Although Godfrey Smith’s new monograph is not explicitly focused on evolutionary medicine, it seems likely that some of his insights will have significant implications for that sub-domain of evolutionary science. To take but one example, his critique of the notion of “selfish genes” is bound to have relevance to future debates about genetic contributions to human disease.
Godfrey-Smith, Peter. Darwinian Populations and Natural Selection. Oxford University Press, Oxford, 2009.
Godfrey-Smith, Peter. Theory and Reality. An Introduction to the Philosophy of Science. University of Chicago Press, Chicago, 2003.