- Putting humans in a hibernation state
to make interplanetary journeys has been a staple
of science fiction films like "Aliens," and "Passengers."
But some people think it might one day become a reality,
and even a solution to get people to Mars.
The only problem?
Humans don't hibernate.
But bears do in ways that we might one day emulate.
- It's not unique to one particular class of mammals.
And I think as long as those pieces are there in humans,
then we could translate that into situation
where hibernation could be induced.
- That's Heiko Jansen.
He studies hibernation in bears.
We talked to him about what human hibernation might
be like and the ways it could help us hurtle
through space or cure our illnesses.
So, tell us a little bit about
what's interesting physiologically
about bears and hibernation.
- Wow, where to start. [laughs]
Everything.
No, it's really quite an amazing physiological state
where the bears can survive for months
without eating or drinking.
Their body temperature,
when they're hibernating, doesn't go that low.
It only drops to about 30 to 34 degrees centigrade
versus 37, but if you compared that to a ground squirrel,
they may drop their temperature to 0,
or sometimes even below zero.
They still reduce their metabolic rate,
how much oxygen they consume,
how much energy they actually consume,
by 75%, which is very similar
to what's happening in a rodent.
They have normal sleep-wake cycles,
they're much less active,
but they still do stand up,
and they may move around their den.
So, they're actually,
some of us in the bear world think that bears
are actually the most advanced hibernator based
on all of those abilities.
- When you're studying hibernation in bears,
what does that actually look like?
- So, I'm fortunate that I belong to a group
at Washington State University.
We have an actual facility with the sole purpose of trying
to understand everything about bear physiology,
bear ecology, and wildlife preservation.
We have these captive animals,
some which were raised in captivity,
others which came from the wild as problem bears.
And so those animals are hibernating right now,
and what we can do is we can go into those dens,
and we can sedate them them,
and we can take blood samples, for example.
We can take a small tissue biopsy to gather the cells
that we need for some of our cell culture work.
We can do a variety of physiological measurements
that we want.
- Is there also a world in which we learn how
to hibernate as humans?
- Because we know that hibernation evolved
in different species over different periods of time,
it's not unique to one particular class of mammals.
And I think humans potentially have some
of the building blocks that
we could use to induce hibernation.
Because of our body mass,
we could not lower our body temperature
to the point that a rodent does and be able to rewarm.
At this point, I see the bear
as being much more closely related
to a human type of hibernation.
- Is there something we can learn about human physiology
by studying bear hibernation?
- Well, I think so.
We've picked a couple of topics to focus
on in our bear work,
and one of them is what's known as insulin resistance.
It's something that diabetics will experience when
their bodies no longer respond to insulin,
and so the tissues can't take up
the glucose in the bloodstream.
Well, bears undergo this process normally
when they enter hibernation.
And so if we understood the mechanisms whereby
they can reverse that insulin resistance once
they come out of hibernation,
we might be able to apply that to a human situation.
The other thing that I think is very interesting
is this ability to lower the metabolic rate even though
the bears are at a relatively high body temperature.
And cancer cells are very active metabolically,
and so ways in which we could turn down
their sort of energetic usage might be a way
to limit some of the problems associated with cancer.
Heart rates decrease tremendously during hibernation,
but the bears don't suffer any cardiovascular problems.
They have no loss of bone density.
They don't lose any muscle mass in hibernation,
so there's a lot of interest in trying to understand,
in terms of people that are bedridden or in space travel,
the loss of muscle mass is considerable,
but bears seem to not succumb to that,
even though they're laying around for about 98% of the day.
- You mentioned just there the prospect of learning
to hibernate as a way to get to Mars.
And I think this is one
of the sort of interesting applications
of hacking human physiology.
How would hibernation help with that effort?
And how do you see that playing out?
- Yeah, the primary benefit there is
that it allows us to be able to use a spacecraft
that doesn't require carrying all the food
that's necessary to bring someone to Mars.
The passengers on the spacecrafts could actually enter
that state of hibernation and so be transported
for who knows how long,
maybe a couple of months even,
without having to eat anything.
You'd require less oxygen,
so you probably wouldn't need as much oxygen on board.
Of course oxygen is light, so that's not as big an issue.
And if we could lower our temperatures,
we would save even more energy.
- What would human hibernation look like,
and why can't we hibernate already?
- You would essentially be asleep.
Your brain activity would be sleep-like,
your blood pressure would be lowered,
and your use of energy,
much like what happens during sleep,
would also be greatly reduced.
Now, when we go to sleep our metabolic rate drops
by about 6% or so, plus or minus.
But hibernation is a much deeper level
of metabolic suppression, and those are the targets
and the pathways that we want to try to identify.
What makes it possible to go from a 6% reduction
in metabolic rate to 75% reduction of metabolic rate.
It may involve some lowering of body temperature,
and that's fine.
Those kinds of temperatures are actually used now
in humans for surgeries
and for doing organ preservation
and transplantation.
We know that by storing something
at a colder temperature actually allows it
to actually survive for a prolonged period of time.
There are of course limits to that,
but I think that the principle there
is gonna be very similar.
- So is this feasible?
- I think once we have a mechanistic picture
of what's going on,
and the genes and the proteins
that we identify are there in humans,
then I think it is feasible.
We don't have a lot of evidence to suggest
that hibernation is induced by one particular thing, right?
It's not there's this factor that appears suddenly,
the animal goes into hibernation.
It's malleable, it's flexible,
and it relies on multiple types of events occurring.
And I think as long as those pieces are there in humans,
then we could translate that into a situation
where hibernation could be induced.
Now, the question is would anyone,
would we want to hibernate for six months
if we weren't going somewhere, right?
And I think the answer is no,
unless it has some obvious benefit.
And I could envision, for example,
maybe someday being able to put someone
into a state of hibernation that has a terminal disease,
and maybe halting the spread of that disease,
or the development of that disease
until a cure is found.
These are all more or less science fiction things
at this point in time, but I think having
that ability would get us one step closer
to being able to do those sorts of things.
Now whether all the organs
would survive something like that,
these are all the questions that remain unanswered.
- Thinking about humans hibernating
seems super science fiction-y.
Is this a new idea because of sort of ambition
to go to space, or is this something
that people have been thinking about for a long time?
- This idea has been around for a really long time.
You see it in movies going back to the '50s. [laughs]
But what's changed over time is the development
of molecular, genetic, and other tools that allow us,
or potentially could allow us, to modulate
or modify our own physiology.
And those kind of things back
in the day were all science fiction,
and now they're science fact.
And it's wrapped up in a lot of ethical issues,
rightfully so, and so we need to be careful.
But I think the basic premise has been there
for a long time, and I think we've just,
we're getting closer and closer
with the development of these tools.
And I think by incorporating what we learn from animals,
as we've done so often,
we can apply that to humans to great benefit.
Who knows where this is going to lead us?
We're still at a very basic stage of trying
to understand, at the very molecular level,
what is really going on,
and what allows these transitions to occur.
And so taking that information into the next level
is gonna be a very difficult process.
- Well, thank you so much for joining us.
- Well, thank you for having me.