Scientists have long been stymied by human regenerative healing -- that is, wholesale regrowth of, say, a severed limb -- an ability inherent in some species but lost on humans. But new research suggests the ability to regenerate isn't based on something newts and flatworms have that we don't; rather, it's something we do have that's keeping us from regenerating tissues.
In one corner, we have the "hairy" frog, Trichobatrachus robustus, hailing from Cameroon.
In the other corner, meet the Spanish ribbed newt, Pleurodeles waltl, hailing from the Iberian peninsula.
Which skin-busting, bone-poking amphibian will win the PopSci deathmatch?