Conventional scientific wisdom has long held that higher metabolic rates lead to shorter life spans. This makes perfect sense, but - like many theories that make perfect sense - turns out to be absolutely wrong. ScienceBlog reports that researchers have determined the most metabolically active 25% of mice in fact live 36% longer than the least active, despite their less efficient and overactive metabolisms. This work raises a number of interesting questions, and demonstrates the necessity of carefully testing what is "common wisdom." Scientists suspect that this extension of life span is due to a lower rate of free radical creation in a less efficient metabolism.