Naked Mole Rats Seem More Alien Than Mammal. What Explains Their Weirdness?
Beady eyes, protruding fangs, wrinkly pores and skin — the bare mole rat appears like it could have dropped all the way down to Earth from one other planet. In actuality, the small mammals are very a lot at residence on our planet, spending a lot of their lives underground in tight-knit societies centered round a dominant queen.
Odd look apart, the bare mole rat is a marvel of unusual talents and diversifications. For starters, they’re cold-blooded mammals — certainly one of few in existence. That trait, like many others they possess, might be because of their subterranean life-style. Life is simply totally different underground.
But it will get weirder. Naked mole rats dwell in societies with insect-like social constructions, have abnormally lengthy life spans and eat one another’s poop. Oh, they usually cannot actually really feel ache.
The rodents, native to East Africa, dwell in dense warrens honeycombed by means of the earth, the place oxygen ranges are low. So researchers from the University of Illinois at Chicago hypothesized in a 2017 examine that bare mole rats wouldn’t want as a lot oxygen as people to outlive. And it seems they want far, far much less — the researchers discovered that the rodents might survive for as much as 18 minutes with none oxygen in any respect, and for hours at very low ranges of oxygen.
When researchers positioned bare mole rats right into a zero-oxygen chamber, their coronary heart charges dropped drastically they usually laid completely nonetheless, showing nearly useless. But as soon as oxygen was restored the rodents grew to become animated as soon as once more, with no lingering unwell results.
How do they do it? Normally, the rodents want oxygen to activate glucose reserves that retailer vitality, identical to people do. But when confronted with oxygen-sparse situations, researchers discovered that bare mole rats can depend on a second system: one which faucets into fructose, one other form of sugar. Though they will’t function at their regular metabolic charges with little oxygen, the rodents can survive situations that might usually kill different small mammals and people alike.
Naked mole rats even have one other superpower: they cannot really feel ache on their pores and skin. The rodents do not reply to warmth or acid burns, and lose two-thirds of their ache receptors by the point they’re adults.
They additionally not often, if ever, get most cancers. Unlike in people, bare mole rats’ cells cease rising earlier than they will type tumors. Researchers noticed in a 2009 examine that their cells stop dividing when a sure density threshold is crossed — a mechanism known as early contact inhibition that stops tumors from ever forming.
This might be a part of the explanation why bare mole rats outlive their rodent counterparts by a number of many years. Where mice and guinea pigs dwell anyplace from two to eight years, bare mole rats can survive for 30 years or longer. But regardless of their death-defying diversifications, the species additionally faces just a few challenges because of their subterranean life-style.
Chief among the many bare mole rats’ issues is inbreeding. This results in, amongst different issues, an elevated susceptibility to illness.
In 2007 researchers examined bare mole rats’ means to battle off a deadly coronavirus, and located their genetic similarities led to extraordinarily excessive mortality charges. In that examine, the inbred bare mole rats have been over 300 p.c extra more likely to die than outbred ones.
And relating to breeding, the bare mole rats’ sperm comprises every kind of abnormalities that stunt its means to fertilize eggs. The males’ swimmers are abnormally formed, with squished heads and odd bulbs typically rising off of them. Plus, they swim a lot slower than different mammalian sperm, because of a scarcity of the mitochondrial rings that sometimes circle sperm tails. Researchers estimate that solely certainly one of each 15 of a unadorned mole rat’s sperm can really swim.
A unadorned mole rat (left) and bare mole rat sperm (proper). (Credit: Roman Klementschitz (mole rat) and Liana Maree (sperm))
The spermatic points they face might be because of the distinctive means a unadorned mole rat colony is organized. Most males by no means breed, which might clarify the stunted sperm. And it’s of their social group that we discover a number of the most peculiar bare mole rat conduct of all.
Naked mole rat society bears extra similarities in some ways to bugs than to their fellow mammals. The rodents dwell in tightly packed burrows, very similar to ants or termites. Their society is hierarchical, with nearly all of bare mole rats functioning as employees. These members do the majority of the day-to-day work of the colony, foraging for roots and tubers, combating off predators and caring for pups.
Like bees, bare mole rat colonies are dominated by a single, domineering queen who produces all of the offspring. She breeds solely with a choose male, producing a brand new litter each 80 days.
Females aren’t born into queendom, although — they need to battle their solution to the highest. This typically ends in vicious battles between females as they vie for the crown.
And that fortunate queen and her mate are likely to dwell longer than the remainder of the pack. A 2018 examine discovered that intercourse appears to gradual getting older in bare mole rats. But even when they don’t seem to be procreating, the rodents appear to stay fertile all through their total lives. Females present no signal of menopause, that means that an older queen might nonetheless start a litter of pups as she nears the tip of her life.
Female employee bare mole rats are tasked with caring for the queen’s offspring. And the queen has a peculiar methodology of passing alongside the message that she’s about to ship a brand new litter: she sends hormonal messages by means of her poop.
Though bare mole rats have sense of odor, their noses can’t choose up on being pregnant hormones that sign a brand new litter is close to. So, the employees eat the queen’s poop as a substitute.
The conduct was found in a 2018 examine the place researchers fed poop pellets from pregnant and non-pregnant queens to employees. They noticed that employees have been extra aware of pups’ cries once they had consumed pellets from pregnant queens.
Naked mole rat pups being tended by employees. (Credit: Neil Bromhall/Shutterstock)
Then, they added the being pregnant hormone progesterone to a non-pregnant queen’s poop and fed it to the employees. The bare mole rats have been nonetheless attentive to the pup’s cries — signaling to researchers that they might choose up on hormonal fluctuations by feasting on feces.
Eating poop not solely passes alongside hormonal messages, it additionally helps bare mole rats digest their meals. The rodents don’t have highly effective abdomen enzymes to interrupt down the robust roots and tubers they eat — so just a few further passes by means of their digestive system will get the job finished as a substitute.
Lessons From Naked Mole Rats
Sure, bare mole rats are odd, however why accomplish that many researchers examine them? Despite their death-defying traits, muddled DNA and unusual social norms, the wrinkled wonders are nonetheless mammals.
Much like how researchers use mice within the lab to grasp how sure processes may work in people, finding out the bare mole rats’ peculiar traits may enable us to translate these talents to people.
Cancer immunity, ache resistance and tolerance to zero-oxygen situations, for instance, aren’t commonplace in people. But finding out these traits in one other mammal might assist us break down the mechanisms behind them — and someday develop therapies for our personal species.
While the analysis continues, our fascination with these unknown creatures stays regular. Several museums throughout the nation have mole rat cams the place you possibly can watch colonies dwell out their lives on-line. And perhaps, for those who’re fortunate, you possibly can see some in individual at your native zoo — and even within the wild.