Are naked mole rats the strangest mammals? - Thomas Park

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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 are extraordinary. Thomas Park explains how mole rats' peculiar traits have evolved over millions of years to make them uniquely suited to survive harsh conditions - especially long periods without oxygen.

Lesson by Thomas Park, animation by Chintis Lundgren.

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.