Individuals and groups in evolution: Darwinian pluralism and the multilevel selection debate.

Outlined here is an updated review of the long-standing 'kin selection vs group selection' debate. Group selection is a highly contentious concept, scientifically and philosophically. In 2012, Dawkins' attack against Wilson's latest book about eusociality concentrated all the attention on group selection and its mutual exclusivity with respect to inclusive fitness theory. Both opponents seem to be wrong, facing the general consensus in the field, which favours a pluralistic approach. Historically, despite some misunderstandings in current literature, such a perspective is clearly rooted in Darwin's writings, which suggested a plurality of levels of selection and a general view that we propose to call 'imperfect selfishness'. Today, the mathematically updated hypothesis of group selection has little to do with earlier versions of 'group selection'. It does not imply ontologically unmanageable notions of 'groups'. We propose here population structure as the main criterion of compatibility between kin selection and group selection. The latter is now evidently a pattern among others within a more general 'multilevel selection' theory. Different explanations and patterns are not mutually exclusive. Such a Darwinian pluralism is not a piece of the past, but a path into the future. A challenge in philosophy of biology will be to figure out the logical structure of this emerging pluralistic theory of evolution in such contentious debates.