O

ur bodies can heal themselves — at least up to a point. We can fuse bones back together again. We can clot a bleeding wound and close it with new skin.

But the human body’s powers of regeneration have their limits. If you lose an arm in a car accident, you won’t grow it back in the days that follow.

There are other species, however, that can regenerate an entire limb. Scientists have long marveled at the ability of salamanders to grow back a new leg that’s no different than the one they were born with. They can rebuild bones, muscles, nerves, and blood vessels, guiding them all into the correct position.

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Today, scientists are studying these salamanders — especially a Mexican species called the axolotl — with the tools of 21st-century biology. They can track the cells that produce new limbs, watching them perform their astonishing developmental dance.

Jessica Whited, a faculty member of the orthopedic surgery department at Brigham and Women’s Hospital in Boston, is doing some of the most important research on the mysterious powers of axolotls. She and her colleagues are discovering key genes that axolotls switch on in order to create a limb from scratch.

Her research may help solve the evolutionary puzzle of why axolotls can regenerate so much more of their own bodies than we can. That puzzle is all the more intriguing because axolotls and we are kin. We share a common four-legged ancestor that crawled around on land around 350 million years ago.

That shared history also means we inherited many of the same genes from that common ancestor. We just use them differently. Someday, scientists like Whited hope, axolotls may help us unlock our hidden healing powers.

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