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Interpreting Genetic Drift: A Challenge to the Analogy with Brownian Motion and a Case for a Way ForwardI claim that recent attempts to compare genetic drift to Brownian motion (a) fail to defend the traditional view of drift as a ‘force’ in evolution akin to Newtonian forces, and (b) inadvertently support the competing view that drift is merely a statistical aggregate of individual events. As proponents of the force interpretation for evolutionary theory continue to struggle to fit drift into their framework due to its lack of vector directionality, it is not clear why the issue should be pursued at all. I argue that little will be gained by seeking a more generous, less restrictive, or some alternative definition of ‘force’ capable of reconciling this problem. At the same time, resolving drift’s status as an evolutionary ‘force’ has no bearing on its status as a cause. Therefore, I suggest we abandon the more tenuous force question and instead elevate the priority of explaining drift’s causal status. If the claim that drift is a cause of evolution can be effectively argued for using a viable theory of causality, it would provide sufficient evidence for defending the traditional interpretation against its primary challengers.
University of Pennsylvania