Thanks to evolution, the grasshopper mouse doesn't feel the intense burning or throbbing that humans or other animals feel when stung by a venomous scorpion.

Although the bark scorpion has one of the most painful and lethal stings in the animal kingdom, the grasshopper mouse fearlessly snacks.

Researchers wanted to know what makes this mouse able to tolerate the pain, and why the venom of the scorpion doesn't kill the mouse. 

They found that the mouse has a modification to the pain receptors that make the toxic venom into a pain reliever instead of stimulant. However, they were unable to find a reason for why the venom failed to kill the mice.