Human organs and tissues have varied capacities for regeneration. Those with the least regenerative capacity—including the brain, spinal cord, heart, and joints—are subject to diseases that are partly the result of the body’s inability to replace damaged cells or tissues in these areas. Learning more about the regenerative processes in other organisms could give clues to repairing damaged organs or even, someday, replacing lost limbs in humans.

Most research organisms used to study regeneration can regrow body parts that humans can’t. These organisms are useful for studying the possibilities of regeneration because humans have similar genes to these animals. However, scientists don’t yet fully understand how to turn on such processes in humans.