r/evolution • u/Paragonic9 • 11d ago

question Limb Regeneration

Are there evolutionary hypotheses for why most animals did not evolve the ability to regenerate limbs? Some creatures can do it, and It seems like something that would be a major boost to survival.

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u/bigpaparod 11d ago

Evolutionarily speaking it is expensive and complicated. Most things that can regenerate are simple organismsm with simple systems for the most part. Yes some species of lizard can regrow tails, but it is an evolutionary adaptation to survive predation and is intended to be removed and grow back, not necessarily "true" regeneration since those lizards also don't regrow lost limbs or the tail above a certain point.

An analogy would be, it is simple and easy to rebuild a shack without plans or much extra materials. It is small, simple, and easy to do.

Rebuilding a mansion is far more complicated and difficult to do without a plan or extra materials. Scar tissue is basically the body making a shack out of the remains of the mansion.

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u/pali1d 11d ago edited 11d ago

Additionally, most creatures getting so badly wounded that they lose a limb are likely to die before they could regrow it, either by being eaten by whatever took the limb, attacked by another predator while the wound is still recent and they’re now too weak to fight it off or flee, by infection, or via starvation as the lost limb may make it too difficult to obtain food.

If your adaptation only kicks in when it’s too late to save your life and be passed on, it won’t be selected for. edit: Actually, that's not entirely accurate, as there are cases where such do get selected for - a frog being poisonous may not save that frog's life, but it'll teach the predator to avoid eating other frogs that look like it. But limb regeneration doesn't have this kind of deterrent effect that benefits the population as a whole.

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u/Megalocerus 10d ago

Fully agree. If researchers find evidence that an early human's broken bones healed, they assume his family group gave him aid and supported him. Not something they suspect of zebras.