Social systems: demographic and genetic issues

International audienceAnimal societies certainly count among the most complex structures that emerged on earth, the latest of the 'major transitions' in evolution. Their study necessarily involves a wide panel of disciplines and a large diversity of approaches. The field is expanding at a rapid pace, which, however, is not going without some turbulence, as testified by recent fierce controversies regarding the concept of inclusive fitness. These battles elicited appeals for 'more cooperation among altruism researchers' (Okasha 2010). In this spirit, we recently organized at the University of Rennes (10-15 October 2010) a workshop on mammalian social systems. The idea was to bring together 'social scientists' working on a diversity of animal models (from bats to elephants and from hyenas to whales) and using a diversity of approaches (from demography to population genetics and from game-theoretical models to behavioural experiments), with the aim of evaluating how key processes (e.g. inclusive fitness and kin selection, versus cooperation and reciprocity, or the interplay between inbreeding, kin competition and kin recognition) might differently affect the emergence and evolution of social systems in a diversity of mammalian lineages, depending on ecological settings or other constraints. This diversity of complementary approaches explains why the several contributions to the workshop collected in the present Special Issue are not all 'pure' molecular ecology