 First, why suppose that the relevant concept of function is an adaptive one, and that dysfunction is a failure of a biological system to fulfill its adaptive function? This analysis of function is often termed the etiological account, and although it is widespread in philosophy of biology it seems to be conceptually tied to fitness rather than health (Méthot 2011). Advocates of a thoroughgoing evolutionary approach to medicine (such as Gluckman, Beedle and Hanson 2009) can be read as providing a framework within which we can make sense of a number of processes that have an effect on health and disease, but not as offering analyses of health and disease that are tied to fitness. Gluckman et al. (p.5) consider the difference between lactose intolerance, which develops after weaning and is normal for most human populations, and congenital hypolactasia, a condition in which newborns cannot digest maternal milk. The former is a consequence of the absence of pastoralism in most historical human populations and does not affect fitness in those populations, whereas the latter would have been fatal in the past and thus was selected against. However, they do not define disease in terms of fitness-lowering: they note rather that an evolutionary perspective can make us sensitive to hitherto neglected causes of pathology and also sensitive to over-hasty judgments of pathology in cases where the condition is normal among populations with a given evolutionary trajectory.