Experimentally evolving exercise endurance: one step at a time.

The author reflects on a paper that study the genetic basis for inherent exercise endurance observed in the rat. He stresses that there is a plethora of evidence that increased exercise endurance or maximal aerobic capacity is linked with several positive health outcomes. In addition, the implication of these findings is that as an organism is selectively bred for a certain phenotype, the different mechanisms that control the phenotype evolve at differing rates.