Fish and some amphibians regenerate their spinal cords after injury. But this ability was lost as higher animals evolved. So, in humans after spinal cord injury, the stem-like cells in the adult spinal cord just start to divide, then stop without repairing the spinal cord. Dr. Michel Rathbone explains why this happens, and some exciting new research findings. It may be possible for humans, like fish and amphibians, to regenerate nerves in the spinal cord using the stem cells already present in their own bodies.