I remember the conversation like it was yesterday. "So let me get this straight," I asked my dad, "your skin can grow back after you cut it, but your arm can't?"
"Nope, never," he said. "But they can give one that's kind of like a robot arm."
I grappled with this information for a solid week before it properly massaged itself into my grey matter. Once you lose a limb, it's gone. As a kid who loved drawing, I quickly uncovered a new phobia in minutes. I'd like to tell you that I've since conquered that fear, but it still lingers in the back of my mind like a haggard squatter in a ransacked flophouse.
My phobia eventually helped me empathize with Spider-Man's foe, the Lizard, more than any other ne'er do well in Spidey's rogue's gallery. For those who don't know, in an attempt to regrow his amputated arm, the Lizard, also known as Curt Conners, spliced his DNA with a reptile's. Since it's a Marvel comic, the experiment went awry and turned him into a monster- yada, yada, yada.
Even though I saw the fictitious experiment go south, a part of my seven-year-old brain was like, "well, hang on, let's just get this guy better funding. He's on the right track. I'm sure Reed Richards could give him some guidance."
As it turns out, Conners was in the wrong class of the animal kingdom. Deers were the correct answer all along. Apparently, the cells in antlers resemble those found in cancer, which is why deers have extremely low cancer rates. Basically, deer genetics have found a way to channel cancer into the thorny protrusion that grows from their heads.
How does this relate to regrowing limbs? The video above explains how understanding the similarities between these cells could potentially help humans transform cancer into helpful cells.