 Clearly, there must be explanations of why humans generally walk on two legs, speak and plan many of their actions in advance. Genealogical, or what have been called “ultimate” (Mayr) or “historical” (Kitcher) explanations can advert to the accumulation of coherence among entrenched, stable properties along a lineage. These may well have resulted from selection pressures shared by the relevant organisms (cf. Wimsatt 2003; Lewens 2009). The fact that there are exceptions to any generalisations concerning contemporary humans does not entail that there is no need for explanations of such exception-allowing generalisations. Plausibly, these general, though not universal truths will have “structural explanations”, that is, explanations in terms of underlying structures or mechanisms (Kitcher 1986: 320; Devitt 2008: 353). These structures, so seems, might to a significant degree be inscribed in humans’ DNA.