Lizards are known for their uncanny ability to regenerate lost body parts from a substance called nAG which stimulates stem cells. Studies discovered the process involved fooling the stem cells into believing the limb was in an "earlier state of time" thus requiring development and growth. People have tried to induce regeneration in humans for years with successful instances occurring under the most rare and unique conditions. For example, a man who severed his fingertip in the prop of a model airplane actually regrew the tip after wrapping it in a pig's bladder. Dr. Stephen Badylak, a regeneration expert at the University of Pittsburgh, indicates regrowth of fingertips is actually common in children under two years old. The Pentagon is sponsoring new research into the process to help wounded veterans. Current tests involve using "pixie dust," a pig extract, to stimulate the host's stem cells into growing the missing limb back over a scaffold. The process has worked before in regenerating animal organs.