Several species of African rodent display remarkable insensitivity to pain, hinting at new ways to manage it in humans.

Scientists have discovered that a half-blind African mole-rat can take about as much wasabi as you can throw at it, for reasons that could lead to new painkillers in humans.

The team, led by Gary Lewin at the Max Delbrück Centre for Molecular Medicine in Berlin, Germany, and including colleagues in South Africa and Tanzania, co-opted nine species of mole-rat, from three families in a test of culinary-oriented pain sensitivity.

The burrowing, buck-toothed natives of East Africa were given paw injections of capsaicin, the compound responsible for the burning sensation of chillies, and allyl isothiocyanate (AITC), which delivers the eye-watering hit of wasabi, the Japanese condiment often eaten with sushi.

For good measure the animals also got a dose of hydrochloric acid.

To see if the critters felt any pain, the team measured how long they spent lifting and licking the affected limb.

Two species were insensitive to the acid, one to capsaicin, and a fourth, the unfortunate-looking naked mole rat (Heterocephalus glaber), displayed a distinct lack of pain to both. Only one rat, however, could hack AITC which, it is worth noting, also gives mustard and horseradish their distinctive punch.

The animal in question was the highveld mole-rat (Cryptomys hottentotus pretoriae) which, the researchers report, was “completely insensitive to AITC”.

A big question is why.

Read the full article at Cosmos magazine here