As humans, our bodies have the ability to naturally regenerate both skin and hair, but we only get two sets of teeth, and that's one set more than many other mammals. Reptiles and fish, on the other hand, have the ability to regrow teeth throughout their lifetime. Though we have guessed that specialized stem cells are involved, the cellular and molecular mechanisms behind tooth renewal in these animals have not been well understood until now. A research team at the University of Southern California's Keck School of Medicine, led by Dr. Cheng-Ming Chuong, has recently published an article in PNAS detailing their study into the regrowth of alligator teeth. They chose a crocodilian model because the dentition is well-organized and implanted in sockets of the dental bone, similar to that of mammals (if more extensive) yet with the capacity for renewal. Contributors to the research included colleagues in Georgia, China, and the Louisiana Department of Wildlife and Fisheries, who presumably provided the live research subjects.