To read about the naked mole rat is to come across information that you wish you never knew – and then to look for more.
The first thing to know about this tunnelling creature is that some people call them sand puppies. The next is that they are “eusocial” mammals. What could that mean, you wonder, and you look it up: as it is with termites, so it is with naked mole rats.
Hundreds of sterile mole rats serve one endlessly pregnant queen. She is around 10cm long, and weighs less than 100g. I Googled a picture: short legs and two rows of nipples, like the capitoline she-wolf but so ugly you could cry. Like the capitoline she-wolf if the capitoline she-wolf was a phallus with teeth. She stops other females reproducing by bullying them: pushing and shoving them, walking on top of them.
When she first becomes the queen, by fighting another NMR (the loser goes off into a faraway chamber to die alone), she will undergo “significant vertebral growth”, stretching until the spaces between her back bones widen. Then she initiates courtship by “thrusting her rear end into the face of the male”.
“When she becomes pregnant, the teats of every colony member, male and female, enlarge, reach their peak at the birth, and then shrink. Just before birth, the female runs wildly through the tunnels,” the essayist Eliot Weinberger writes in a piece so powerful it has eclipsed all of his others. People ask him to read it again and again.
Because that is the thing about NMRs: each piece of information is worse than the last, but you cannot stop reading. The queen’s pups – she’ll give birth to more than 1,000 over her lifetime – will beg other NMRs for their faeces. The females she bullied are waiting: they’re likeliest to try to kill and replace her while she is giving birth. NMRs eat their young dead and alive – leaving only the heads and teeth. The teeth, of which there are four, can move individually, “like a pair of chopsticks”, according to the Smithsonian’s National Zoo. When they eat, they hold a piece of food in their front paws and bite into it. They chew with their mouths open.
NMRs look exactly like they were sewn together from the hand skin of a very old person. “The eyes are tiny with thickened eyelids and minute eyelashes,” reads one description. They are almost entirely bald, but they have hair between their toes.
They live longer than any other rodent. Joe, the oldest we know of, turned 39 two years ago. They defy the law of ageing that applies to the rest of us: Gompertz’s mortality law says that your mortality rate increases exponentially with age. But Joe’s owner found no change in his cells from one decade to the next. The queen stays fertile for decades: “For a human that would equate to having babies at 300 years old,” according to Wired. They don’t feel chemical or inflammatory pain, though they do react if pinched. In fact, just about the only thing that does kill naked mole rats is getting beaten up by other naked mole rats. That and herpes.
Almost without exception, they cannot get cancer. Scientists trying to find out why tried to make naked mole rats grow and divide in a nutrient-rich liquid – instead of the liquid acting on the cells, the cells changed the liquid to syrup. The key, they discovered, might be something called hyaluronan. It is also the thing that makes their skin – oh God – especially stretchy. “If you grab an animal, it feels like you’re removing their skin,” according to one of the scientists.
You want more? When fighting snakes, they might climb on top of each other to block the way. “And all the predator sees is many sets of gnashing teeth,” according to the San Diego zoo. The tunnels and chambers of a single colony can extend more than a kilometre wide. They have a chamber for storing bulbs and roots, and another that is the toilet. It doubles as a place where they roll around so that they can all smell the same as each other, because they are also extremely xenophobic. When attacking, and usually killing, foreign NMRs, they release an “obnoxious odour”.
What are you still doing here? Why can’t you stop reading? I’ve asked myself the same thing. I am ending this column precisely so that I can keep reading about naked mole rats. I hope to find something comforting. There’s this I suppose: even though their burrows and tunnels and nests are steaming hot, they like to sleep all huddled together, for warmth. Aw.
Helen Sullivan is a Guardian journalist. She is writing a memoir for Scribner Australia
Do you have an animal, insect or other subject you’d like to see profiled by this columnist? Email helen.sullivan@theguardian.com
• This article was amended on 6 August 2024 to clarify that naked mole rats are not the world’s only eusocial mammal.
