Dawdling deep beneath eastern Africa is one of the quirkiest mammals alive: the naked mole rat. The oddball rodent is bald, basically blind, buck-toothed, cold-blooded, and – we now know – immune to the stinging pain of acids.

It could chow down on chili peppers or trot through acids without feeling any irritation.

This invulnerability comes from another biological eccentricity – naked mole rats lack a chemical called Substance P, which triggers the feeling of burning pain in other mammals.

"Their insensitivity to acid was very surprising," professor Thomas Park told LiveScience; he’s a neurobiologist from the University of Illinois at Chicago. "Every animal tested – from fish, frogs, reptiles, birds, and all other mammals – every animal is sensitive to acid."

(Credit: Rochelle Buffenstein, City College of New York)

Mole rats probably evolved this resistance after centuries of crawling through oxygen-starved tunnels. As the rodents exhale, these tight passages build up high levels of carbon dioxide, which can turn the air acidic.

Normal air is less than 0.1 percent carbon dioxide. At 5 percent, humans will “feel a sharp, burning, stinging sensation in our eyes and nose,” Park said. But naked mole rats “live in up to 10 percent carbon dioxide.”

Park hopes that by studying mole rats scientists can discover new ways to treat people with chronic pain. We need your help, little guy!