A feature story in a recent issue of the journal Nature described four solar system bodies that are puzzling to evolutionary scientists.¹ Specifically, the article discussed the rings of Saturn, two of Saturn's moons (Enceladus and Titan), and Jupiter's moon Io. These four bodies all exhibit properties that cannot persist for billions of years.

People often take for granted every muscle-based movement our bodies make. But the structure and function of muscle movement is as complicated as any biological task in humans or animals.