From what I’ve read, Salamanders of all kind retain their stem-cell embryonic growth capabilities in their early life (after birth). But once they become adults, they become more mortal like the rest of us. But Axolotls for some reason never lose their ability.

An axolotl is a salamander that remains in its larval form throughout its life, while most salamanders go through a metamorphosis during sexual maturity, so it’s not surprising it retains embryonic growth capabilities.

There’s actually a theory that hominid ancestors at some point split off from other great apes by also not going through the typical great ape sexual maturity. For examples humans look a lot more like juvenile chimps that we do sexually mature chimps.

My theory would be that neoteny goes hand-in-hand with the traits of domestication (social friendliness, high tolerance of strangers, etc), and that humans are effectively self-domesticated.

Some of this is alluded to in https://en.wikipedia.org/wiki/Neoteny_in_humans which is a fascinating read, as is this very thread. Thanks for the food for thought!

I believe there's also a hypothesis that our ancestry back to the Devonian or Cambrian was based on neoteny/paedomorphism where a particular creature living on the sea floor, when in the infant stage, has a limb for propulsion which it loses when it finds a nice spot to settle. Our very distant ancestors didn't lose those limbs and evolved into the distant precursors to placaderms, bony fish, and, well, terrestrial fauna.

Isn’t the whole body growing from the same point at the same pace in a lot of instances when someone is in the womb (except when something like thalidomide is introduced)? It would seem a big challenge would be to have a part of a human body, at any number of stages after birth, maybe especially after full development, regrow from nothing, and excluding, at the very least, the areas of the body in proximity to it.

I’m obviously not an expert.