Why Can’t Humans Regrow Limbs? An Evolutionary Biologist Explains

Humans likely cannot regrow limbs because our immune system prioritizes rapid wound closure over regeneration.

Unlike salamanders, which form a blastema and rebuild missing parts, human cells quickly seal injuries instead of reverting to a regenerative state.

The tradeoff may come from adaptive immunity and wound-healing cells like macrophages and neutrophils, which help protect us but limit limb regrowth.

The finding helps explain a major barrier in regenerative medicine and why restoring human limb regeneration is so difficult.