 A closely related way to vindicate models of cultural evolution looks to the question of the general features of inheritance systems that make for evolvability in a lineage. This project has been pioneered in recent years by Kim Sterelny (e.g., 2001, 2003, 2006a, 2006b, 2007, 2012). Once again, let us illustrate the general nature of these issues by beginning in the organic realm. Darwin’s theory is intended to explain adaptation. The basic conditions for natural selection do not, in spite of appearances, suffice for the appearance of functional traits. A system in which offspring resemble parents with respect to fitness-enhancing traits may not develop complex adaptations. The environment needs to cooperate: if selective pressures change very quickly then there will be no sustained environmental demands of the sort that might build complex adaptations over time. Development also matters. If ontogeny is set up in such a way that changes to any one trait tend to be accompanied by changes to all other traits, then the chances are that cumulative adaptation will be particularly hard to come by. For even in those cases where a mutation contributes positively to the function of one trait, the chances are that it will contribute negatively to overall fitness in virtue of its disruption of the functioning of other traits. Development also needs to make a wide range of variation available. If it is highly constrained, so that only a small number of forms are possible, then selection is not presented with a broad enough range of raw materials from which to fashion complex traits. It also seems that cumulative adaptation relies on the suppression of ‘outlaws’ (Sterelny 2001, 2006b). We saw in the previous section that group selection is often held to be an ineffective agent of group-level adaptation, on the grounds that it is vulnerable to ‘subversion from within’. This occurs when individual organisms go it alone, sabotaging complex features of group organisation in favour of their own fitness. Individual-level selection, in contrast, can build individual-level adaptations. This is because, by and large, genes in a given human organism share a ‘common fate’—they do not behave as though they were in direct competition, struggling for representation in future generations. When genes genuinely ‘go it alone’, for example by sabotaging meiosis so that some have greater chances of appearing in future generations than others, then the overall integrity of the organism can be compromised, and individual-level adaptation is undermined.