Answer: Tree Shrew

For the longest time, it was believed that humans were the only mammals that liked spicy food. Mammals, universally, have abundant receptors for capsaicin—the compound in peppers that creates the spicy “burn”—and, as a rule, don’t enjoy eating it. Dusting the bird seed you place outside with pepper powder, for example, is a great way to keep the squirrels away, but the birds won’t mind. Birds don’t have receptors for capsaicin and, in fact, there’s an evolutionary argument to be made that pepper plants evolved to harbor a compound that drove mammals away while still attracting birds in order to more successfully spread their seeds.

With that in mind, it was understood only humans enjoyed torturing themselves with the dubious pleasure of lighting their mouths on fire with increasingly spicier peppers. But it turns out we’re not alone in the mammal family when it comes to avid pepper consumption though. The humble little tree shrew loves chowing down on peppers and spicy plants too.

Interestingly enough, however, the tree shrew doesn’t eat peppers for the thrill of it, but solely for the nutrition. In fact, they don’t seem to feel the burn at all. Researchers at the Kunming Institute of Zoology found that a single genetic mutation in tree shrews radically dampens their perception of capsaicin. They believe the shrews originally adapted in order to eat Piper boehmeriaefolium, a spicy plant with leaves that produce capsaicin—their ability to eat hot peppers with immunity is just a side effect of their original adaption.