Kinematic and Dynamical Aspects of the Price Equation
Lorenzo Baravalle, Victor J. Luque
Königlicher Pferdestall, Hannover
16 / 03 / 2023

In a previous article (Luque and Baravalle 2021), we argued for an analogy between (genetic) evolutionary theory and Newtonian mechanics. In this talk, we aim to make this analogy clearer. We think that many disagreements about the empirical content of the Price equation are, to a greater or lesser extent, related to the fact that a certain description that Price provided of evolutionary processes is incorrectly taken as an explanation of such processes. By reconstructing and analysing the phenomenological framework from which the Price equation is derived, we shall argue that this framework supplies the kinematic of evolution. We shall suggest that we can think of this framework – which we call the “Pricean framework” – in analogy to Galilean kinematics. This has two consequences. The first is that the Price equation is not trivial. On the very contrary, the analogy with Galilean kinematics entails that the Price equation identifies an empirical relation between magnitudes, which any evolutionary theory is called on to explain. The second consequence, however, is that the Pricean framework, by itself, lacks of dynamical features; it needs to be complemented by further theoretical assumptions. These assumptions, intended to make explicit the causes of evolutionary change, are not included in the original Pricean framework. Nevertheless, different dynamical laws (e.g., Hamilton’s rule) can be derived from the Pricean formalism, plus additional assumptions, with relative ease. These dynamical laws explain the behaviour described by the Pricean kinematics in specific contexts. Thus, differently from Newtonian mechanics, in evolutionary biology we do not have just one fundamental law of motion (i.e., Newton’s second law), but rather a constellation of laws, grounded on a common framework.

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