Starfish, salamanders, and planarian flatworms share a seemingly magical trait: the ability to regenerate body parts they've lost. While humans may never boast quite the same ability, scientists are perfecting ways to create different types of replacement tissue using stem cells or techniques that kick-start regrowth and development. Thanks to their efforts, the fabled "human spare-parts kit" may become a reality sooner than you think.
By Elizabeth Svoboda



