General Knowledge

Are naked mole rats the strangest mammals?

What mammal has the social life of an insect, the cold-bloodedness of a reptile, and the metabolism of a plant? Bald and buck-toothed, naked mole rats may not be pretty, but they’re extraordinary. With a lifespan of 30 years, their peculiar traits have evolved over millions of years to make them uniquely suited to survive harsh conditions, especially long periods without oxygen.

In the deserts of East Africa, naked mole rats feed on root vegetables. They dig for the roots with teeth that can move independently, like chopsticks. But even with these special teeth, a single naked mole rat doesn’t stand a chance of finding enough food; the roots are large and nutritious, but scattered far and wide.

A large workforce has a much better chance, so naked mole rats live in colonies. Similar to ants, bees, and termites, they build giant nests. Housing up to 300 mole rats, these colonies feature complex underground tunnel systems, nest chambers, and community bathrooms. Also like insects, naked mole rats have a rigid social structure.

The dominant female, the queen, and two to three males that she chooses, are the only naked mole rats in the colony who have babies. All the other naked mole rats, male and female, are either soldiers, who defend the colony from possible invaders, or workers. Teams of workers are dispatched to hunt for roots, and their harvest feeds the whole colony.

Living in a colony helps naked mole rats find enough food, but when so many animals live in the same underground space, oxygen quickly runs out. Mammals need a lot of oxygen; we use it to make the energy that fuels everything from maintaining our body temperatures to our heartbeats to voluntary movements.

Without oxygen, we quickly die. In fact, no other mammal could survive the oxygen depletion experienced in a naked mole rat colony. Naked mole rats can thrive in low oxygen in part because they’ve abandoned one of the body functions that requires the most oxygen: thermoregulation.

Most mammals are warm-blooded, meaning they have to keep their body temperature consistent. Naked mole rats don’t get enough oxygen to do this. Instead, they’re the only mammals whose body temperature fluctuates with their environment, making them cold-blooded, like reptiles.

They also have a special type of hemoglobin, the molecule in the blood that transports oxygen. Their hemoglobin is much stickier for oxygen than ours and can pick oxygen up even when it’s scarce. In response to a real oxygen emergency, naked mole rats enter a state of suspended animation.

They stop moving, slow their breathing, and dramatically lower their heart rate. This greatly reduces the amount of energy, and therefore oxygen, they need. At the same time, they begin to metabolize fructose, like a plant. Fructose is a sugar that can be used to make energy without burning oxygen.

Usually, mammals metabolize a different sugar called glucose that makes more energy than fructose, but glucose only works when oxygen’s available. Human brain and heart cells have some cellular machinery to use fructose, but not nearly as much as naked mole rats. Naked mole rats are, in fact, the only mammals known to have this ability.

While we can hope humans won’t ever need to exclusively live in underground tunnels, there are many situations where we would benefit from needing less oxygen. During heart attacks and other medical emergencies, people often die or sustain debilitating organ damage from oxygen deprivation.

Could we replicate the naked mole rat’s use of the fructose pathway for human health? It took millions of years of evolution to bring the behavior of an insect, the temperature regulation of a reptile, and the energy production of a plant together in one little mammal, but maybe, with enough study, we can replicate just a few of their wild adaptations.

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