   While this controversy has been divisive (Schwartz 2002), there are prospects for a synthesis. First, Eshel and Feldman (2001) distinguished between “short-term evolution”, the evolutionary dynamics of a fixed set of genotypes, and “long-term evolution”, bouts of short-term evolution interspersed with introductions of new genetic variation. They noted (page 162) that “long-term evolution proceeds by an infinite sequence of transitions from one fixed set of genotypes to another fixed set of genotypes, with each of these sets subject to short-term evolution…” Optima are often not accessible in the short-term due to constraints on available variation. However, genetic variation may be introduced over the long term so that the population eventually reaches an optimum. The substantive point is that we now understand how apparent short-term impediments to optimality can be resolved over the long term. Mutations must appear at the right time and the ecology must remain stable over the long term; whether these conditions are met frequently enough in nature to justify the optimality approach is an empirical issue (see also Hammerstein 1996). The second prospect for synthesis is Wilkins and Godfrey Smith's (2009) proposal that the truth of empirical adaptationism, and the concomitant application of optimality models, depends on the intended “grain” of resolution of the evolutionary analysis. At a fine grain of resolution, when there are few peaks in the adaptive landscape, most observed populations may be on or near these peaks. Adaptationism is appropriate at this resolution. If we “zoom out” and look at a grand landscape over large regions of morphospace, the situation changes. At a very coarse grain of resolution, much of morphospace is empty and constraints often explain why certain regions remain unexplored by biological evolution. Adaptationism is inappropriate at this resolution.