The desert is famous for its creepy-crawlies. Snakes, scorpions, spiders and centipedes can all pack a venomous punch, and most of us keep our distance. It’s only sensible.
But don’t tell that to the grasshopper mouse.
They’re are only 6 inches long from nose to tail, and an ounce in weight. But these mice are pure carnivores. While grasshoppers and other insects are a mainstay, they’ll happily eat lizards and other rodents. And they’re utterly unfazed by creatures whose venom would have us writhing for hours.
And these remarkable rodents may have something profound to offer our species.
Scientists Ashlee and Matthew Rowe work in the desert borderlands.
“And you’re out at night,” Ashlee said. “It’s an adventure. It’s beautiful. You’re in the desert, lots of stars.”
“Scorpion collecting isn’t for everybody,” Matthew said, “so not everybody falls in love with it. But the students who did, fell in love with it big time."
The Rowes bonded collecting scorpion in the Southwest. Soon, they’d joined forces – in marriage, and in research.
One of their shared interests was the Arizona bark scorpion. This Sonoran Desert creature is the most dangerous scorpion in the U.S. Its sting can kill an infant, and for anyone, the pain is intense and long-lasting.
While Matt’s speciality is desert ecology, Ashlee’s is neurophysiology, and she became fascinated by the scorpion’s venom. That venom is incredibly complex, a “cocktail” of hundreds of component peptides, each of which targets victims in different ways.
Analysis of bark-scorpion venom revealed something surprising: it included components specifically targeting mammals. That suggested a defense against a mammalian predator.
Grasshopper mice were known to eat tarantulas, centipedes, and giant hairy scorpions. But scientists assumed they knew better than to mess with the fearsome Arizona bark scorpion.
In 2001, the Rowes captured a grasshopper mouse and an Arizona bark scorpion. They put the two in proximity. The grasshopper mouse went straight to work, shrugging off the stings, and dispatching its venomous prey.
“So as it turns out, grasshopper mice love bark scorpions,” Ashlee said, “and they had no problem, no hesitation, attacking them. They do get stung. And it was like, oh, they were totally unaffected.”
“It's a scorpion that can kill humans,” Matt said. “So for the mouse to be able to take it, there's got to be something really special going on.”
Through molecular and genetic analysis, Ashlee learned the mice have specific adaptations that make them resistant to both the lethality, and the pain, of the scorpion’s venom. In fact, through a chemical jiu-jitsu, the mice use the venom to shut down their pain pathways. They alchemize the venom into a painkiller.
The neurology of mice and humans is similar. By “reverse engineering” the mouse’s pain-killing chemistry, the Rowes’s research could lead to a new painkiller for humans.
“I think nature is worthy of our study and our admiration and our wonder by itself,” Matt said. “But there is a potential here for some great human benefit, because if Ashley can figure out the configuration, it could be a new kind of analgesic that has the benefits of opioids, but doesn't have the tragic consequences of addiction to opioids.”
West Texans are lucky – unlike the Arizona variety, our region’s bark scorpion is no medical threat. But the Rowes have studied grasshopper mice here, and they’ve found that they possess some of the venom-resistance of their Sonoran Desert kin.
When grasshopper mice set out on their nocturnal hunts, they emit a long cry – a high-frequency version of a wolf’s howl. Listen for it in the desert night. It’s the sound of a tiny apex predator whose evolutionary magic could transform medicine.
