Evolution of the relative marginal value of health qh/a(t) with age due to variation in A0. The solid thick line, labelled “Unperturbed”, represents the unperturbed path. The perturbed paths are shown for the T fixed case (dotted line, labelled “T fixed”), scenario I, associated with small life extension TI (dotted line, labelled “I”), and scenario II, associated with large life extension TII (dotted line labelled “II”).