How do salamanders regenerate lost limbs?

Question

Is it something in their genes, like a nutrient or protien that makes this possible?

I have not a clue and I'm curious.

Answer 1

Amphibians evolved from fish and their limbs grew out of the fins of the fish. The pelvic fins formed the hind legs and the pectoral fins formed the forelimbs.
It has been proposed that the homeotic transformation in the expression of a Hox gene accounted for the evolutionary transition. Some fish have the ability to regenerate fins, and more importantly, amputated fins respond the same way to retonic acid, a molecular signal in regeneration, as amphibian limbs. This suggests that both limb structures have common mechanisms that were preserved during evolution and supports the theory that regeneration has a developmental and evolutionary origin as opposed to adaptive.

Answer 2

Saaay, that natural regeneration of lost body parts is pretty neat. Crabs do it too. So how come everybody can't do it ? Well, children, since we higher life forms have evolved to the point that we just don't do that any more so that we can, er, survive better, maybe we will just have to go backwards and devolve before we can figure it all out.
You are not the only one who does not have a clue.
Keep your curiosity.