Subtitles section Play video Print subtitles Hey there! Welcome to Life Noggin! Have you ever wondered if it was possible for humans to regrow body parts? Why is it that when a person loses an arm, only the wound is healed rather than the body regrowing their lost limb? In the spirit of Dr. Connors, let's find out. I just hope we don't all turn into Spider-Man villains. So humans can't regrow their own limbs, correct? Well, that might not be entirely true. As an embryo, long before your birth, you may have had the ability to replace your developing limbs. Through scientific surgery, researchers have shown that at the embryonic stage of development, frogs can regenerate their developing limbs. This has even been shown in mice, which like humans, are mammals. It is yet to be proven the same with human embryos, but with this evidence, the theory is that vertebrate embryos, including humans, can regenerate their limbs if they are damaged or amputated. However, other than a few special and small cases like the regeneration of fingertips, humans don't really have this ability after birth. But do any other animals? It just so happens that salamanders have this super awesome superpower! They are the only vertebrate that can regrow their limbs and many other body parts throughout their lifetime. In fact, the axolotl, a Mexican salamander, can regenerate almost anything, from their eyes, to their spinal cord, to even parts of their brain. These adorable little guys are amazing! And I want 20 of them. So how do salamanders do it? Well, when a human loses a limb, their cells close the wound and a blood clot forms. This leads to a scab over the wound and an eventual scar in the place of where the limb was. But for a salamander, scar tissue never forms— a striking difference between their regeneration and a human wound healing. A salamander's wound closes more rapidly and cells rush to the amputation site. These cells revert back to a less specialized state and begin creating the blastema, which is the bud of a new limb. As the blastema grows, it begins to form the outline of a new limb and the foot. The cells begin creating new tissue by proliferating and differentiating into things like muscle and bone. The new leg lengthens, filling out the missing segments between the amputation site and the toes. The whole process usually lasts around two months, and then the salamander has a fully regenerated limb. It's perfect for a cute little high five! Go science! But in humans, the blastema never grows. Some scientists think that's because humans don't have all the genes necessary to facilitate such a level of regeneration. But others think that humans don't have this regenerative ability because it might make them more likely to develop cancers. But even if humans could regrow their limbs, there still might be an issue. Let's take a look back at that adorable little axolotl with the findings of two recent studies. The researchers found that, like biological wrecking balls, certain jumping genes need to be shackled in the axolotl's cells or they might disrupt their process of regeneration. They discovered that proteins found within the little water monsters allow them to prevent these jumping genes from causing havoc. So, regeneration is really complicated and maybe for right now, humans can't regrow their limbs. But these studies at least give scientists hope that we could learn better methods for treating human conditions, like wound healing and regenerating simple tissues. Hey, even becoming just a little bit more like Wolverine would be awesome! I'm Blocko, and I'm the best at science communication. And I have claws. Eat your heart out, Hugh Jackman! So what do you think? What limitations of humanity would you like science to be able to overcome? Let me know in the comment section below! Have you ever wondered why winter doesn't kill all the plants and fish? Check it out here! Lucky for our aquatic friends, when the temperature outside falls below the freezing point of the water only the top layer of lakes or river typicallys freeze. As always, I'm Blocko and this has been Life Noggin. Don't forget to keep on thinking!