Sixteen common misconceptions about the evolution of cooperation in humans  Stuart A. West, Claire El Mouden, Andy Gardner  Evolution and Human Behavior  Volume 32, Issue 4, Pages 231-262 (July 2011) DOI: 10.1016/j.evolhumbehav.2010.08.001 Copyright © 2011 Elsevier Inc. Terms and Conditions

Fig. 1 Inclusive fitness is the sum of direct and indirect fitness (Hamilton, 1964). Social behaviours affect the reproductive success of self and others. The impact of the actor's behaviour (yellow hands) on its reproductive success (yellow offspring) is the direct fitness effect. The impact of the actor's behaviour (yellow hands) on the reproductive success of social partners (blue offspring), weighted by the relatedness of the actor to the recipient, is the indirect fitness effect. In particular, inclusive fitness does not include all of the reproductive success of relatives (blue offspring), only that which is due to the behaviour of the actor (yellow hands). Also, inclusive fitness does not include all of the reproductive success of the actor (yellow offspring), only that which is due to its own behaviour (yellow hands; adapted from West et al., 2007a). A key feature of inclusive fitness is that, as defined, it describes the components of reproductive success which an actor can influence, and therefore which they could be appearing to maximise. Evolution and Human Behavior 2011 32, 231-262DOI: (10.1016/j.evolhumbehav.2010.08.001) Copyright © 2011 Elsevier Inc. Terms and Conditions

Fig. 2 A classification of the explanations for cooperation. Direct benefits explain mutually beneficial cooperation, whereas indirect benefits explain altruistic cooperation (Hamilton, 1964). Within these two fundamental categories, the different mechanisms can be classified in various ways (Bergmüller et al., 2007; Frank, 2003; Lehmann & Keller, 2006; Sachs et al., 2004; West et al., 2007a). These possibilities are not mutually exclusive—for example, a single act of cooperation could have both direct and indirect fitness benefits, or interactions with relatives could be maintained by both limited dispersal and kin discrimination. Our dividing up of conditional enforcement strategies is for illustration only, as a detailed discussion is beyond the scope of this paper, and provided elsewhere (Bergmüller et al., 2007) (adapted from West et al., 2007a). Evolution and Human Behavior 2011 32, 231-262DOI: (10.1016/j.evolhumbehav.2010.08.001) Copyright © 2011 Elsevier Inc. Terms and Conditions

Fig. 3 The different types of group selection. The white circles represent cooperators, whereas the grey circles represent relatively selfish individuals who do not cooperate. Panel A shows the “old” group selection, with well-defined groups with little gene flow between them (solid outline). Competition and reproduction is between groups. The groups with more cooperators do better, but selfish individuals can spread within groups. Panel B shows the “new” group selection, with arbitrarily defined groups (dashed lines), and the potential for more gene flow between them. The different groups make different contributions to the same reproductive pool (although there is also the possibility of factors such as limited dispersal leading to more structuring), from which new groups are formed. Panel C shows the “newer” group selection, which emphasises the more proximate mechanism of inter-group competition as a factor shaping the evolution of social behaviours. Panel D shows cultural group selection, in which social behaviours can be horizontally transmitted between group mates, for example with all individuals in the group imitating the behaviour of one “teacher” (T). Evolution and Human Behavior 2011 32, 231-262DOI: (10.1016/j.evolhumbehav.2010.08.001) Copyright © 2011 Elsevier Inc. Terms and Conditions

Fig. 4 The scope of inclusive fitness theory and group adaptation. Irrespective of the extent to which selection is within or between groups, natural selection will lead to organisms that appear to be maximising their inclusive fitness (Frank, 1986; Grafen, 2006a; Hamilton, 1975). In contrast, individuals will only be selected to maximise group fitness in the extreme scenario where there is negligible within group selection (Gardner & Grafen, 2009). Evolution and Human Behavior 2011 32, 231-262DOI: (10.1016/j.evolhumbehav.2010.08.001) Copyright © 2011 Elsevier Inc. Terms and Conditions