[MUSIC PLAYING]
PETER KLOPFER: I would guess that people
think of lemurs as cuddly little animals,
but we don't know a lot about them.
Lemurs are limited to this one island.
They're very hard to maintain.
So there's not a long history of study.
But because they are such a diverse and yet closely related
group of species, they're a very promising source
of information.
I'm Peter Klopfer, and I'm a biologist whose principal focus
is on lemur biology and, in particular,
hibernation in the fat-tailed dwarf lemur.
They are primates.
Indeed, if you look at their genome,
they are almost as closely related to us
as are chimpanzees, which is one of the reasons
that studying hibernation in these animals
is a little more relevant to the human condition
than studying other hibernators, such as the ground squirrel,
for example.
They offer us an enormous bed of riches.
The dwarf lemurs are found naturally
only on the island of Madagascar.
They're nocturnal.
They're generally solitary.
And they're called fat-tailed lemurs because they store fat,
prior to entering hibernation, in their tails.
They live in an area where there's a prolonged dry period,
so you either shut off your metabolic rate or starve.
And so the question that suddenly popped up in my mind
was, how do these animals manage to hibernate
for six to seven months at temperatures
well below that needed for brain activity
when prolonged sleep deprivation is fatal?
Well, the Duke Lemur Center is dedicated
to this kind of research.
We really have the only captive colony of dwarf lemurs outside
of Madagascar.
And so we have a small facility that's
designated as a hibernaculum.
And they usually go into these PVC pipes.
And it gives me a clear view of the animal.
And they feel safe and comfortable inside them.
They just curl up inside and go into torpor.
Torpor means the animal's thermostat is disabled,
and they become as cold-blooded as a snake.
It's the only primate that we know that has that capacity.
Needle electrodes placed under the scalp
allow us to continuously record brain activity.
We have temperature loggers, which
are chips that are attached to collars that the animals wear.
After lots of trial and error, we
discovered that they periodically
warm up just enough for the brain to become active enough
so they can sleep.
Sleep is an active brain state.
There is electrical activity there
in a very distinct pattern.
That sleep phase persists for a few hours.
And then they go back into torpor,
and the brain becomes inactive again.
Now, most of the energy these animals expend
during their six-month period of hibernation
is devoted to firing up the metabolic system
during the arousals.
So that points to the importance of the arousal,
and in turn, that points to the importance of sleep.
But all kinds of other things are happening as well.
These animals, when they emerge from torpor,
within minutes are as agile as they
are at any time in their lives.
How do the muscles maintain that capacity?
How does the kidney manage to stay alive?
We haven't a clue.
These are all questions which, given our present technology,
require invasive techniques.
We can't employ these.
First of all, the Duke Lemur Center
prohibits any kind of invasive procedure.
Secondly, these are endangered species.
And indeed, we needed to get exceptions
from the various agencies that govern animal care in order
to induce hibernation to the degree that we do,
which is far less prolonged than in nature.
We humans possess the same genes that
are activated in the dwarf lemur when they initiate torpor.
What we lack is the switch that turns them on.
So if we could identify that switch,
there's very real possibility that we could induce
prolonged torpor in humans.
That would be a great asset.
If you're needing heart surgery, slow the heartbeat down.
Slow the circulation down.
And of course, my friends in NASA
have cottoned on to the idea to have a long space
travel without the need for food or exercise.
I started studying lemurs in mid-1960s.
I never really thought about how long the lemurs
would continue to engage me.
We've hardly scratched the beginning of understanding
lemur physiology in general and the physiology of hibernation,
in particular--
just beginning to get a picture of what's
going on in these little bodies.
LUKE GROSKIN: Hey there.
This is Luke Groskin, video producer for Science Friday.
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