Why Can’t We Regrow Limbs?

Salamanders and crabs can do it, why can’t humans? And could we do it in the future?

Man, I bet this bird wishes that it was a salamander, so it could grow another leg. But do salamanders wish that they were birds so they could fly? Oh wow, crazy thoughts. Photo by Timothée Mägli.

As I sit at my computer, wiggling my fingers to create these words, I occasionally have a fear about losing one or more of these attached digits.

In recent decades, humans have made huge strides in creating prosthetic limbs. We have artificial legs that are able to adaptively support our weight and adjust to match our speed, enabling athletes with artificial limbs to run practically as fast as any other runner.

(For consideration: Oscar Pistorius, the Paralympic athlete who is a double amputee, can run around 25 miles per hour on a treadmill. Usain Bolt, on the other hand, clocks in with a top speed of 27 miles per hour.)

We’ve also created artificial hands that can grasp, twist, and flex, capable of far more than just a pirate’s hook. Researchers today are even working on limbs that respond to neural signals, allowing an amputee to control an artificial hand through thought, just like how you can control your hands in front of you now.

Despite these advances, however, we’re still firmly in the real of robotics. We can’t currently compete with members of the animal kingdom, like salamanders and crabs.

These animals aren’t unduly bothered by the loss of a limb. They simply regrow it.