Reisman and Forber's experiment may not demonstrate that drift is a cause, but only that population size is a causal factor of evolutionary change

This is because it’s a bit unclear if drift is actually what is being manipulated in Dobzhansky and Pavlovsky’s (1957) experiments, or if it is just population size—and population size does not seem to be a process. Perhaps Reisman and Forber have simply shown that population size is a causal factor of evolutionary change in populations undergoing drift. They also seem to be taking Woodward’s account very literally, in that they seem to think that the “variable” that has to be manipulated must b