Why Can’t Humans Regrow Limbs? An Evolutionary Biologist Explains

InnovationScienceWhy Can’t Humans Regrow Limbs? An Evolutionary Biologist ExplainsByScott Travers,Contributor.Forbes contributors publish independent expert analyses and insights. I write about biodiversity and the hidden quirks of the natural world.Follow AuthorMay 09, 2026, 08:30am EDTSalamanders regrow entire limbs. We share their evolutionary blueprint. So why can’t humans do the same? The answer implicates our greatest biological achievement.gettyLet’s say a salamander, due to an environmental or attack-based injury, ends up losing its left foreleg. Three weeks later, a small, cone-shaped mound of new tissue will have emerged from the wound. If we give it another month, that mound will become a fully functional limb — bones, tendons, nerves, blood vessels, skin — indistinguishable from the one that was removed. Now imagine a human patient in the salamander’s place. Same injury. Same timeline. What they have three weeks later is a surgical closure, a course of antibiotics and the beginning of a prosthetic consultation.We share common ancestry with the salamander. Our limbs are built from the same basic evolutionary blueprint. So the question isn’t merely academic: What, exactly, did we lose? And more unnervingly — did we lose it at all, or did evolution simply bury it beneath layers of immunological armor and metabolic pragmatism?What Salamanders Have That Humans Don’tMost people think of regeneration as an exotic superpower. In reality, it exists on a continuous biological spectrum, and humans are not entirely outside of it.Planarian flatworms can be sliced into hundreds of fragments and each piece will grow into a complete organism. Salamanders can regenerate entire limbs, portions of their hearts and sections of their spinal cords, repeatedly throughout their adult lives. And human children, under approximately seven years of age, have also been documented regrowing cleanly amputated fingertips — skin, nail and all — provided the wound is left open and untrea...