The historical transformation of individual concepts into populational ones: an explanatory shift in the gestation of the modern synthesis.

Abstract

In this paper, I will conduct three interrelated analyses. First, I will develop an analysis of various concepts in the history of biology that used to refer to individual-level phenomena but were then reinterpreted by the Modern Synthesis in terms of populations. Second, a similar situation can be found in contemporary evolutionary theory. While different approaches reflect on the causal role of developing organisms in evolution, proponents of the Modern Synthesis refrain from any substantial change by reinterpreting and explaining individual-level phenomena from a population perspective. Finally, I will approach these historical and contemporary debates by arguing for the statistical reading of natural selection, which holds that explanations by natural selection are statistical. My main conclusion is that the historical conceptual reinterpretations belong to a new explanatory strategy developed by the Modern Synthesis based on population thinking. Adopting the statistical point of view has three advantages for the issues discussed in this paper. First, understanding historical conceptual change as part of an explanatory shift fits with the emergence of population biology as a discipline that employs statistical methods. Second, concerning current debates in evolutionary biology, the statisticalist reading can validate the goal of both sides of the dispute. It ascribes an invaluable role to the population statistical explanation of the MS and also commends the study of developmental and organismal causes of adaptive evolution. Finally, the division of explanatory roles in evolutionary biology, embarrassed by statisticalism, can be related to the different interpretations that important biological concepts have undergone throughout history and contemporary biology, i.e., that the division of explanatory roles allows for a division of conceptual interpretations.