Drift as Constitutive: Conclusions from a Formal Reconstruction of Population Genetics

ROFFÉ, ARIEL

HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES

STAZIONE ZOOLOGICA ANTON DOHRN

Lugar: Nápoles; Año: 2019

0391-9714

This article elaborates on McShea and Brandon?sidea that drift is unlike the rest of the evolutionary factors because it isconstitutive rather than imposed on the evolutionary process. I show that theway they spelled out this idea renders it inadequate and is the reason why itreceived some (good) objections. I propose a different way in which their pointcould be understood, that rests on two general distinctions. The first is adistinction between the underlying mathematical apparatus used to formulate atheory and a concept proposed by that theory. With the aid of a formalreconstruction of a population genetic model, I show that drift belongs to thefirst category. That is, that drift is constitutive of population genetics inthe same sense that multiplication is constitutive in classical mechanics, orthat circle is constitutive in Ptolemaic astronomy.  The second distinction is between eliminatinga concept from a theory and setting its value to zero. I will show that eventhough drift can be set to zero just like the rest of the evolutionary factors(as others have noted in their criticism of McShea and Brandon), eliminatingdrift is much harder than eliminating those other factors, since it wouldrequire changing the entire mathematical apparatus of standard populationgenetic theory. I conclude by drawing some other implications from the proposedformal reconstruction.