Possible mechanisms for a multiple-level model of evolution

Abstract

Many of the commentaries cohere around two major points of criticism. The first is that we have omitted discussion of the mechanisms that are assumed to operate at levels 2, 3, and 4.Campbell, Cloak, Dewsbury, Eckberg, Mundinger, Pulliam, Richerson & Boyd, Slobodkin, Simon, Williams, andWahlstenall make comments that bear on this point. The second point is that we have omitted discussion of the fact that "organisms change the environment by their activities" (Lewontin) and thereby modify the selection pressures that act on them. Apart from Lewontin, this point has been raised in different forms byBarkow, Chase, Hull, Perzigian, Ruyle, and less directly bySlobodkin. Stemming from these two basic omissions there is a third general criticism. Numerous commentators have pointed out that we have failed to discuss sufficiently either the extent or nature of the constraints that may or may not be operating on supraordinate evolutionary processes as a function of their nested relationships to subordinate evolutionary processes within our scheme (Barkow, Campbell, Cloak, Chase, Lenington, Lewontin, Perzigian, Peterson, Pulliam, Richerson & Boyd, Simon, Slobodkin, andWilliams). We start by acknowledging these three basic omissions. We agree that they exist and that they are serious.