Why Some Animals Can Regrow Their Limbs But Humans Cannot

A regenerative Ted-Ed lesson written by Jessica Whited and animated by Anton Bogaty explains why certain animals, such as salamanders, can regrow their limbs but others, including humans, cannot.

For some animals, losing a limb is a decidedly permanent affair. But for salamanders, particularly axolotls, amputation is just a temporary affliction. Not only can they grow back entire limbs in as little as six weeks, they can also regenerate heart and even brain tissue.

While humans can’t regrow entire limbs, we can heal cuts to our skin using the same cluster of regenerating cells known as a blastema, which salamanders use to regrow limbs. A connection is there, albeit the source is still unclear.

But one of regenerations essential ingredients doesn’t belong solely to salamanders: the blastema. Deer antlers use a similar healing tissue to regenerate each year, even though their skin scars like ours. …And even humans can regenerate the tips of our fingers and toes in a surprisingly similar manner. We still don’t know whether this ability is tied to our shared ancestry with salamanders or fueled by distinct biological mechanisms.