A major focus of evolutionary medicine is trying to understand why natural selection has left the body vulnerable to disease.  This month’s Evolution lead article by Douglas J. Futuyma offers a major and long-needed review.  The focus is more on on species and the limits of their adaptation to new environments, than bodies and traits that seem suboptimal, but the article is nonetheless a valuable contribution to evolutionary medicine.

EVOLUTIONARY CONSTRAINT AND ECOLOGICAL CONSEQUENCES

by Douglas Futuyma
Evolution Volume 64 Issue 7, Pages 1865 – 1884

Abstract

One of the most important shifts in evolutionary biology in the past 50 years is an increased recognition of sluggish evolution and failures to adapt, which seem paradoxical in view of abundant genetic variation and many instances of rapid local adaptation. I review hypotheses of evolutionary constraint (or restraint), and suggest that although constraints on individual characters or character complexes may often reside in the structure or paucity of genetic variation, organism-wide stasis, as described by paleontologists, might better be explained by a hypothesis of ephemeral divergence, according to which the spatial or temporal divergence of populations is often short-lived because of interbreeding with nondivergent populations. Among the many consequences of acknowledging evolutionary constraints, community ecology is being transformed as it takes into account phylogenetic niche conservatism and the strong imprint of deep history.