In the regeneration game, mammals pale before such creatures as salamanders. Humans barely avert complete disappointment, regrowing digit tips if they are severed past the last joint, while salamanders are superheroes, regrowing any structure that can be cut off without killing them. Though the salamander is a stalwart regeneration model, research is expanding into model organisms such as the zebrafish and mouse, which offer broader tools and possibly better translation to clinical medicine. "We want to take advantage of the strength of genetics," says Ken Muneoka of Tulane University in New Orleans, who switched from working on salamanders to digit-tip regeneration in the mouse.