"There's this interesting thing called regeneration... Take, for example, a salamander, which can regrow, say, its tail. Well, first of all—how is that even possible? And secondly—why can a salamander do it, but we can't?" asks the host, slightly hesitating, wearing a stylish shirt and square glasses. The invited guest, seemingly a biologist with a flowing, shaggy mane resembling an old lion, squints slyly, smiling beneath thick mustache and beard.
"It is possible. That's an easy answer. You simply recall the embryonic program for tail development and activate it at the spot where you cut it off. The cells stop thinking they're adult salamander cells; they start thinking they're embryonic salamander cells, and not just any embryonic cells, but those located in the area where the tail should grow; and the tail grows back. You're essentially restarting the tail growth program. In this sense, it already exists—it just needs to be restarted. But why some can do it and others can't... That's a good question... Well, never mind!"
The host laughs cheerfully. It seems he collects such answers from his guests. The scientist thoughtfully raises his eyes toward the ceiling.
"There are people who actually study this... Belarusian colleagues at the Institute of Bioorganic Chemistry, I think... They've tried to understand what differences exist in the genomes of organisms capable of regeneration versus those incapable of it. By the way, I don't know if salamanders can regrow their tails. Axolotls can—they're larvae, after all. That's more for embryologists. But, you see, here's the problem... This isn't actually harmless. Because the ability of cells to revert to an embryonic program—that ability exists in us as well—is cancerous tumors. And our attempt to regrow a new arm instead of the one we've lost would result in something terrible growing out instead of an arm... Well, beyond that, I don't know. Maybe it could be useful to someone... I don't know. After that, it's just speculation."