Original subtitles

WILLIAM SHATNER: A fatal plague

that ravaged the Byzantine Empire.

A bizarre affliction of biblical proportions.

And a disturbing disorder

where people dance themselves to death.

Plague,

smallpox,

tuberculosis and influenza.

These are only a few of the contagious diseases

that have killed billions of people

over the course of human history.

Just saying their names

conjures misery and pain,

and the impact of these deadly infections

has changed the world more than a few times.

How do lethal maladies begin

and then start to silently spread?

What happens when a medical epidemic

turns into mental hysteria?

And while antibiotics and vaccines can help

keep diseases like smallpox and plague under control,

just how close are we to catching

the next unstoppable outbreak?

Well, that is what we'll try and find out.

♪ ♪

News reports surface that a new, highly contagious disease

first discovered in Wuhan, China

is spreading like wildfire.

In a matter of weeks, the lethal virus known as

"coronavirus," or "COVID-19," sweeps the globe.

On March 11,

as the number of infections and deaths

continue to climb,

the World Health Organization declares

that the outbreak has become a worldwide pandemic.

RAJ DASGUPTA: What separates, clinically,

coronavirus from other common viruses

such as influenza is that it knows how to hide itself.

It has what we call a period where you could be asymptomatic.

That means "without symptoms."

That's a chance to pass that virus to other people,

keeping the disease going on and spreading.

Most of the time, when you wait for these symptoms,

you've already missed it.

SHATNER: According to experts, the origins of many viruses

remain shrouded in mystery.

DASGUPTA: It's so difficult

to determine the origin of viruses because

when you want to study that virus,

you have to separate what is the natural history

of that cell?

So, one of the important things

that epidemiologists are looking at right now

is what did we learn from the past?

What should we be looking at? Where should we be looking?

GRAHAM PHILLIPS: Some of the

earliest records of plagues are found

in ancient India, China, the Middle East,

and they talk about plagues occurring

before the very first civilization, around 3200 BC.

SHATNER: Throughout human history, there have been accounts

of devastating afflictions that defied understanding

at the time they happened.

But perhaps a closer examination of these plagues

will provide some lessons about infectious diseases

and how they begin.

Emperor Justinian sits atop a powerful throne,

but lurking in the shadows

is a hidden enemy about to consume his kingdom.

A plague, started by a bacteria,

comes out of the East

and infects.

This simple bacteria ended up killing

almost one half the population of the entire Old Empire.

With that type of death toll,

the economic and social ramifications were catastrophic.

Everything that Justinian had tried was now collapsing.

His military collapsed, his economy collapsed,

and everything that he tried to do was of no avail.

(people coughing)

KIRSTEN FISHER: Justinian plague is caused by a bacterium, Yersinia pestis.

It can either enter humans directly

through-- from saliva, or-or coughing.

It usually manifests itself

in terms of swelling of lymph nodes.

The skin turns black and basically dies.

And then there's a progression of fever

and chills and eventual death.

ARIEL BAR TZADOK: As Justinian's Empire was collapsing and breaking,

and his military strength was waning,

because the science of medicine in those days

was far more primitive than we have today,

people cry out, "Why... why is this happening?"

SHATNER: The Plague of Justinian, as it became known,

ultimately killed an estimated 50 million people.

The vast Byzantine Empire was crippled,

not by an invading army

but by an enemy they could not see

and did not understand.

At the time, since the existence of bacteria and viruses

had not yet been discovered,

many believed that the invisible force

that caused the plague was God himself.

It was a belief that was widely accepted

because people would read in the Bible

about how pestilence from the past

had been created by the hand of God.

Whenever humanity is infected

by something greater and beyond human understanding,

it has always been

psychologically understood

to be an expression of the wrath of God.

We have, in the book of Exodus,

the famous ten plagues of Egypt.

Moses had come back after seeing God on the mountain

to free the Hebrews from slavery.

He went before the pharaoh and asked to let his people go.

Of course, the pharaoh said no.

Therefore,

the Hebrew God sent a number of plagues

through Egypt.

BAR TZADOK: The Bible stories are clear.

The order of the plagues are well documented in the Bible.

We know, of course, that there was the turning

of the Nile into blood.

There were the frogs, the lice, the pestilence

and, of course, the great plagues of

the Three Days of Darkness,

and of course, the death of the firstborn.

JULYE BIDMEAD: The biblical writer who is writing what happens

and is inspired by God

does say that the plague stopped

after the Hebrews were finally free.

So, perhaps there was some divine intervention from God.

But we'll never know because miracles

are very difficult to prove.

SHATNER: Can ancient plagues be attributed to

a higher power at work?

Well, it's a fascinating theory.

And perhaps divine intervention could be the source

of a strange affliction

where a person mysteriously bleeds

as if they've been crucified.

SHATNER: Every spring,

billions of Christians all over the world

gather to observe

a solemn day of reverence called Good Friday.

According to Christian tradition,

Good Friday commemorates

the crucifixion and death of Jesus Christ.

This sacred practice has been performed

for nearly 2,000 years,

and involves attending mass,

the veneration of the cross

and elaborate processions.

While Good Friday is a somber occasion,

the Crucifixion is a pivotal event

that is at the heart of Christianity.

STEPHEN ROSSETTI: When you look at the spirituality

of the Christian faith,

the Crucifixion of Jesus is not

only a tragedy of death,

it's a sign of the sufferings of Jesus.

When we think of the Crucifixion today,

we think of Jesus' wounds when he was crucified,

which includes the holes in the hands,

in the feet,

in the side.

We think of the crown of thorns.

SHATNER: The Crucifixion is clearly a profound cornerstone

of the Christian faith.

But curiously, for centuries,

people have suffered from a rare and disturbing condition

that is connected to the death of Jesus Christ.

This bizarre affliction is known

as "stigmata."

McGOWAN: Stigmata occurs

when an individual is marked in a physical way

that represents the wounds

that Christ suffered on the cross.

Most commonly, stigmata happens in what is referred to

as the five wounds of Christ,

which is two in the hands,

two in the feet

and one on the side.

HOROWITZ: Since the Middle Ages,

there have been untold thousands of cases.

In the strictest terms, stigmata,

although they do involve physical suffering,

are considered

a blessing, a privilege.

It's almost as if the stricken individual

is bearing a holy or divine burden.

SHATNER: How can wounds that mirror those of Jesus Christ

inexplicably appear on ordinary people?

It seems to defy all logic.

But perhaps clues about this phenomenon can be found

by examining the first documented instance of stigmata.

McGOWAN: The first recorded case of stigmata

occurred with St. Francis of Assisi in 1224.

St. Francis went to the mountains of La Verna

to meditate and to pray.

And then suddenly, Francis had a vision of a seraphim.

A seraphim is a particular kind of angel,

a fiery angel with six wings.

And the seraphim held in his possession the crucifix.

His wings were wrapped around Jesus on the cross.

And from this crucifix, this image of Jesus,

came forth these rays,

and these rays penetrated Francis

in the form of stigmata.

Francis' stigmata was incredibly intense.

Nothing like this had ever happened before.

And not only did he have wounds

that were openly bleeding on his hands,

Francis was quite ill after

he received the stigmata, and he died two years later.

Every day of those two years, he did, in fact,

suffer with stigmata.

SHATNER: Accounts of stigmata are both fascinating

and deeply unsettling.

For many Christians, they are proof

of divine forces at work in our world,

but many experts are skeptical

and insist that stigmata must have

a scientific explanation.

ROSIE FALODUN: In terms of stigmata-like symptoms,

there are some medical conditions

that have been attributed to spontaneous bleeding,

but it's still very much misunderstood.

One of them would be hematohidrosis.

It's known as bloody sweat

because when the body is under extreme stress,

the sweat glands tend to become more fragile

and can bleed spontaneously.

It typically manifests as droplets

of blood on the skin, most commonly in the forehead,

the arms and the legs, without any apparent physical cause.

But it can't be said that they are

the exact cause of stigmata.

HOROWITZ: When a proposed stigmata occurs,

the Vatican typically will do everything possible

to account for the healing

within standard medical protocol.

The Vatican disputes, ignores or disproves

vastly greater numbers of miraculous claims

than it actually validates, and so,

if the Vatican is able to verify stigmata,

they are considered miraculous.

SHATNER: Is it possible that a genuine case of stigmata

is an actual miracle, as the Vatican claims?

Many believe that the best evidence lies in the story

of the most famous case in modern history--

the stigmata of Padre Pio.

LYNN PICKNETT: Padre Pio was

a Capuchin friar who in 1918 celebrated mass

and immediately afterwards started bleeding

from the hands and feet,

but there were certain peculiarities about it.

It never scabbed over.

And it gave off a very sweet perfume,

which is known as the odor of sanctity.

McGOWAN: When Padre Pio was suffering from his stigmata,

he said that the pain was so extreme

that he thought he might die.

He was embarrassed by the blood

and embarrassed to be showing these marks on a regular basis.

And he was always trying to cover them

with the sleeves of his robe

so that people wouldn't see the blood.

ROSSETTI: The Vatican's response to great mystics in the church

has often been to persecute them, at least initially.

They did that with Padre Pio.

They were skeptical.

At one point they thought they were self-inflicted

and so they, uh, silenced him.

They basically shut him away in a monastery.

But thousands of people would go to attend his mass

and line up for confession for days.

ANDREW COLLINS: It was not until long after Padre Pio's death

in 1968 that the Vatican had relented

and saw him as a genuine stigmatist.

He was finally canonized and beatified by Pope John Paul II.

This was at the beginning of the 21st century.

Now thousands of pilgrims come from all over Italy and beyond

to venerate at his tomb every month,

and so his memory is something that is celebrated

by Catholics in every part of the world.

SHATNER: For the moment stigmata remains a controversial

and captivating affliction that offers no easy answers.

But in 16th-century France

another condition emerged that was no less baffling.

It was a disturbing phenomenon which led hundreds of people

-to dance themselves to death. -(laughter)

(woman screams)

SHATNER: This historic city, built along the Rhine River,

is known for its stunning network of canals,

remarkable medieval architecture,

and the famous astronomical clock of Strasbourg Cathedral.

But over 500 years ago, in July of 1518, this town was the site

of one of the strangest maladies in human history.

It's known as the dancing plague,

and it started when a townswoman named Frau Troffea

spontaneously burst into dance.

WALLER: Frau Troffea is said

to have stepped outside of her house

in the city of Strasbourg...

...and then began to dance,

and she danced for hours and hours and hours,

and apparently, at first, eyewitnesses thought

that she may have been trying to irritate her husband

or that this was some kind of joke,

but then the dance stretched into the evening

and then into the night.

She collapsed.

She got up the next day and began again.

And at that point people realized

that a very strange phenomenon was unfolding here.

PICKNETT: Frau Troffea went on hopping around and dancing

in the heat of the summer, but she wasn't enjoying it.

She was unfocused, glassy-eyed, dissociated,

and just jerking around and dancing,

and she actually couldn't stop.

SHATNER: Frau Troffea reportedly danced for a week straight.

The constant exertion took a toll on her health,

and she was sent to a remote monastery to recuperate.

But strangely, after Frau left Strasbourg,

the dancing didn't stop.

WALLER: Within about two or three weeks,

dozens more people

had been consumed by this same urge to dance and dance

for hours and days in an altered state of consciousness.

By the end of August,

perhaps 400 people were all dancing,

in some cases on and off for weeks.

Their toenails fell off, their feet were lacerated,

their shoes were full of blood.

And then some of them dropped dead.

It was estimated 15 a day dropped dead,

maybe 400 in all over the course of the two months.

It was a terrifying and terrible thing.

What's so remarkable about these events of 1518

is that we have copies

of the memos sent among the members

of the governing circle of the city.

There are intense debates within the city

as to what is causing this outbreak of dancing,

and they make quite clear,

these people do not want to be dancing.

They are absolutely involuntary.

SHATNER: What could have possibly triggered

such a bizarre and deadly affliction?

At the time the people of Strasbourg began to suspect

that the dancing plague was the work

of the devil.

COLLINS: This was something that was seen as a form of possession,

so they started to look

at possible supernatural explanations,

and the first thing that they thought of was

this possibly being instigated by the devil himself.

And so they tried to purge every kind of sin from the city.

It didn't work.

SHATNER: When banning sin failed, the townspeople wondered

if the dancing plague was not the work of the devil

but rather a Catholic saint by the name of Vitus.

WALLER: St. Vitus is an important saint

in the late medieval European Church.

There was a very strong belief

that there were a number of saints

who could both cure you of a particular disease

and, if you were a sinner,

then they would punish you by inflicting that disease.

St. Vitus was believed to cause movement disorders,

including compulsive dancing,

so it made complete sense to people at the time

that if anybody was dancing wildly,

it's because they'd somehow offended St. Vitus.

So what they then do is that they bundle people into wagons

and take them to a shrine dedicated to St. Vitus

located about 30 miles north of Strasbourg.

Interestingly, they put red shoes on them.

They cover the red shoes in holy oil and holy water

and they lead them round the shrine in a circle,

and then we are told

most of the people recovered their sanity,

so it seems that they cured it

by appealing to the supernatural beliefs

of the people who had been afflicted.

SHATNER: Was the dancing plague both caused and cured

by a higher power?

While it made sense to people in medieval Europe...

...in modern times experts have proposed

a more scientific theory.

They claim that this ghoulish dancing frenzy was

the result of mass psychogenic illness,

or as it's more commonly known, mass hysteria.

FALODUN: Mass hysteria is when a group of people

are experiencing the same physical symptoms

without a definitive physical cause of those symptoms.

For example, if you're in a social setting

whereby someone is experiencing a symptom,

you can then believe that that's also happening to you.

WALLER: Today the most popular theory

for the 1518 dancing plague

is that this is an example of mass hysteria,

but it's not always the case that unusual behavior

is mass psychogenic illness.

We're talking about several hundred people dancing

for days or weeks, some of them dying.

Could mass hysteria really be what started

the spread of the dancing plague?

Or was it the work of the devil?

Whether it was psychological or spiritual in nature,

the dancing plague is certainly a lesson in human behavior.

As is the case of a 3,000-year-old virus

that spread around the world and became

one of the deadliest diseases on Earth.

SHATNER: Spanish conquistadors led by Hernán Cortés arrive

at Tenochtitlán, the capital of the Aztec Empire,

bearing dreams of conquest

and an insatiable desire for gold,

but they also brought with them a lethal, infectious disease.

TOK THOMPSON: Smallpox is introduced into the Americas very dramatically

at a specific point in time and alongside the European invasion.

So this is a tremendous sort of clash of civilizations,

the likes of which the world had never seen before

and will never see again.

The single most deciding factor

as to why Native American civilizations fell so rapidly

was the introduction of smallpox.

FISHER: So, smallpox is a virus.

It causes these sort of irregularly spaced,

pustuly skin lesions

and had a devastating effect

on-on Native Americans, um, in the New World.

GRONVALL: In Europe most people had experienced smallpox.

They had the scars or they had it as children,

but there was no immunity in the New World.

There was no immunity among kids,

there was no immunity among adults,

and so, when this new disease came, everybody was vulnerable,

and so it spread like wildfire.

SHATNER: Although the exact numbers will never be known,

many experts estimate

that a staggering 95% of the Indigenous population

would eventually die from smallpox,

but what's even more chilling

is the fact that smallpox ran rampant for thousands of years.

GRONVALL: I am astounded

by how far back smallpox goes.

For most of human recorded history,

we believe it's the same strain that was infecting

one person after another, this human chain of infection.

The Egyptian pharaoh Ramses V

had scarring on his face

that's consistent with smallpox.

SHATNER: It is estimated that smallpox has killed

between 300 and 500 million people

in its more-than-10,000-year existence.

Which begs the question: how did we finally beat it?

Well, it just so happens that the cure for smallpox

was discovered in a small English village in the 1790s.

GRONVALL: In the late 1700s doctors were noticing

that milkmaids did not seem to be affected by smallpox

and their complexions remained unscarred.

And people were starting to make that connection

that there might be immunity from catching

a different kind of poxvirus-- cowpox--

so milkmaids were exposed to the cowpox virus,

probably got infected,

and were then immune to smallpox.

Edward Jenner was an English physician

and decided to test this observation

and took a piece of an ulcer

from a cow that was infected by cowpox

and gave it to an eight-year-old boy

and then, a little bit later,

gave this little boy a dose of smallpox.

Fortunately, the eight-year-old boy did not develop smallpox

and was actually protected.

Because it wasn't like a direct viral intake, right, you would,

you would get a slightly, um, lesser version of the disease,

but because you had been exposed to it,

you would, of course, then have immunity,

so it was probably the first instance

of a crude version of vaccination.

SHATNER: As it turns out, Edward Jenner's revolutionary experiment

is remembered today for its inspiration,

its sheer audacity,

and because it provided a new defense

against infectious disease

which we now refer to as "the vaccine."

GRONVALL: The word "vaccine"

comes from the virus name vaccinia,

which was the virus that was the cowpox-derived virus

that left people immune to smallpox.

Vaccines prevent disease,

and some vaccines can last for decades

and some vaccines need to be given every year.

For smallpox, people had to get vaccinated every ten years.

SHATNER: Vaccines are humanity's single greatest weapon against plagues.

Rooted in science and not superstition,

they provide a powerful way to fight outbreaks.

GRONVALL: The last naturally occurring case

of smallpox was identified in 1979,

and in 1980 the World Health Organization declared

that smallpox was eradicated,

so no longer spreading from person to person.

Eradicating smallpox was the biggest public health victory

in the history of the human race.

SHATNER: The eradication of smallpox

is the most famous use of a highly effective vaccine,

but there are some diseases that are harder to cure.

MICHIO KAKU: There are viruses

for which we have no vaccines at all

because they mutate too rapidly.

And so, because viruses mutate,

there's a certain limitation to what you can do with vaccines.

DASGUPTA: The minute you get too confident

and you think that we defeated Mother Nature,

somehow it always finds a way to come back.

SHATNER: It appears that even with our technological

and medical advancements,

the ability to isolate, contain,

and even eradicate certain diseases

will remain an ongoing endeavor.

And in some cases discovering the source

of the affliction can be shocking,

like in the case of a deadly disorder

caused by a gruesome tribal ritual.

SHATNER: This group of tropical islands

located in the Southwest Pacific Ocean

is one of the most remote places on Earth.

During the 1970s it was discovered

that a local tribe known as the Fore

was afflicted by a strange and deadly illness.

SCHUTT: The Fore people lived up in the mountains of this island.

There were probably about 36,000 of them that were spread out

across the mountain valleys in Northern New Guinea.

They lived in 170 different hamlets

with people who spoke six different languages.

When the Westerners started to interact with the Fore,

missionaries and anthropologists found

an alarming number of them were dying of a strange disease

that nobody had really seen before.

One of the symptoms of this disease

is something that is known as pathological laughter.

(laughing)

You know, inappropriate laughter, giggling.

Major magazines and newspapers called it laughing death.

SHATNER: At the time experts estimated that the laughing death

killed 200 Fore people every year.

The Fore called the illness kuru,

which translates to "trembling" in their dialect.

The disease was puzzling to scientists,

who could not determine its cause,

and in 1981 Dr. Robert Klitzman traveled to Papua New Guinea

to try and solve the mystery.

When I went there for the first time,

I wasn't sure what to expect,

but I learned many things.

Initially it was called the laughing death,

which is sort of a misnomer.

People did engage in what seemed like laughter,

but it really was sort of uncontrollable expressions

and movements that they had.

Kuru causes a number of symptoms.

It is a neurological disease

somewhat similar to Parkinson's disease or Alzheimer's.

The symptoms are loss of muscle control over one's body,

shaking, inability to walk,

and it has mental symptoms as well,

so people may not be able to control

their emotions or what they say.

The disease was terrifying in many ways.

The symptoms usually, from start

to the person's death, take about a year.

It's invariably fatal.

The Fore people believed that the disease

was caused by sorcery.

So they believed that a sorcerer would take

something that belonged to you

and wrap it around a stone and bury it and cast a spell on it,

and that may sound ridiculous to some of us,

but they'd say, "That's just magic."

The world in which they lived was this kind of a world.

SHATNER: Was kuru the result of supernatural forces,

as locals believed?

It's an intriguing notion,

but doctors eventually suspected that the real culprit

was that the Fore participated in the gruesome practice

of consuming human flesh.

HOROWITZ: When Western anthropologists

began to study some of the communities

of Papua New Guinea in the 1930s,

they discovered practice of a ritualistic,

religious-based funerary cannibalism.

The Papua New Guineans who engaged in cannibalism

saw the consumption of the brain

as a way of imbibing that person's life force.

It was a devotional practice.

KLITZMAN: When they practiced cannibalism,

at one feast, I calculated

that there were 56 people present,

53 of whom then died of the disease.

So it was pretty devastating.

Now, every time someone died, they would consume the brain.

I met people, for instance, who would say,

"Well, I ate a foot," or "I ate a hand,"

and they were still alive.

And so, the concentration of the kuru

was highest when they would consume the brain.

SHATNER: Perhaps it's not surprising

that eating human brains is not good for your health.

But how did this practice

lead to the bizarre laughing symptoms of kuru?

Kuru is caused by something called a prion,

an infectious protein that is in all of our brains.

And in roughly one out of every million people or so,

it flips the wrong way.

And when it's flipped,

it could lead to other proteins

flipping in our brain and forming clumps

that could kill brain cells.

Kuru probably happened because someone

in the Fore group had such a protein flip the wrong way,

and that person was then consumed by other people,

and that led to proteins in their brains flipping.

And when they died, they were eaten,

and the rest is history, it continued to spread.

SHATNER: The story of kuru is as fascinating

as it is disturbing.

But what's even more unsettling is that this type of disease

has harmed people not just in Papua New Guinea

but all over the world.

Except, we call it "mad cow disease."

SCHUTT: In the 1980s,

British cattle became stricken with mad cow disease

because farmers feed them supplements,

and these supplements are made up of dead cows

infected with prion disease.

And then people would consume that.

Eventually, over the course of 15, 16 years,

178 people in the U.K. died

from what became known as mad cow disease.

FALODUN: Mad cow disease

or neurodegenerative diseases such as kuru

can manifest upwards of 70 years after the ingestion

of some contaminated, um, food or livestock.

And so, it's very unclear

as to whether or not it can happen in the future.

The study of kuru is important for many reasons.

One is, of course, the fact that the symptoms

in humans from eating an infected cow

are basically the same symptoms that we saw with kuru.

So, they provided this unique glimpse

on what can cause a disease that's different

than what anyone had thought before.

SHATNER: Could our understanding of the laughing death disorder

help us to better identify and avoid

stange outbreaks in the modern world?

Perhaps, and now more than ever,

people are going to great lengths

to dodge diseases and even death itself.

Their secret is to remain frozen for centuries.

SHATNER: In a sprawling industrial park

on the north side of the city stands the headquarters

of the Alcor Life Extension Foundation.

Like most cutting-edge medical facilities,

the doctors and scientists here work day and night

to provide care for their patients.

Except, in the case of Alcor,

the patients...

...are all deceased.

In our view, people who are declared legally dead today

are potentially revivable.

Alcor's mission is to take a patient

who cannot be helped by today's medicine into the future

where, hopefully, more advanced technology

can repair and revive them.

We're here in Alcor's patient care bay.

In this room, we have all 184 of our human patients

in these dewars, these cryogenic dewars,

essentially very large, expensive vacuum flasks.

So, in each one of these containers,

there are four whole-body patients.

On this side, you can see

that I can put my hand on here without any problem,

but just a few inches further in is minus 320 Fahrenheit.

It's extremely cold.

People say that we freeze people colloquially,

but that's not strictly accurate if we do it right.

Our patients are essentially in something like a long-term coma,

except there is no metabolic activity whatsoever.

SHATNER: To date, 184 deceased patients

lie in deep freeze within Alcor's facility,

in the hope that, one day, they'll be resurrected.

This bizarre form of potential immortality

is known as cryonics.

Cryonics is the process of freezing the human body,

perhaps just the human head,

in order to stop the biological process of decay.

So, the hope is, if you could freeze somebody alive,

even with an incurable disease,

perhaps you can thaw them out at some point in the future

when science has found the cure for that disease.

In that sense, perhaps you can defeat cancer,

defeat all the ravages of old age.

Perhaps even become immortal.

MORE: Professor Robert Ettinger, a physicist,

started the cryonics movement in the 1960s,

where he proposed to store people

at ultracold temperatures,

where there's the potential that future technology

could repair and revive them.

Right now, there are many companies that do this.

There are hundreds of frozen individuals right now

across the United States.

SHATNER: Worldwide, it is estimated

that at least 500 people have been placed

in cryonic suspension,

most notably, baseball Hall of Famer Ted Williams.

There are even those who claim that Walt Disney's body

is preserved in a cryonics facility.

But is there any reason to believe

that this strange process could actually work?

If you live in the countryside, you know that, come wintertime,

the lakes freeze over.

But if you ever look right on top of the lakes,

you'll see frozen organisms.

Fish and frogs.

And then, come springtime,

some of them spring back to life again,

when you thought they were frozen solid.

What's the trick?

The trick is that Mother Nature

has created an antifreeze

to lower the freezing point for these animals

such that, even though it appears

as if they're frozen solid,

the bodily fluids inside these animals still flows,

and these animals are still alive,

even though their metabolism rate is very close to zero.

So, in some sense, we're trying to copy nature.

And it turns out that some forms of tissue can,

in fact, be frozen almost indefinitely.

SHATNER: If cryonics is able to deliver

on its promise of immortality as many hope,

could it eventually mean that death itself

will one day come to an end?

MORE: Cryonics really is about giving people choice

over how long they live.

We think that, in the future,

we should be able to revive cryonics patients

and rejuvenate them and let them go about their lives again.

What we want, really, is indefinite lifespan.

KAKU: If, in the future, someone can show

that you could be revived after being frozen solid,

then the whole question of immortality is on the table.

We're not there yet,

but there's no law of science that says you can't do it.

Perhaps the future for treating a deadly virus

will be to simply put a patient on ice

until a cure can be found.

In the meantime, it's reassuring to know that modern medicine,

along with an understanding of how outbreaks begin and spread,

has made great strides in controlling the escalation

of contagious diseases.

But will killers like smallpox still be around

for another 3,000 years?

Or can a new plague emerge

that's impervious to antibiotics?

While we can attempt to protect ourselves from deadly pandemics,

just when the next unstoppable outbreak will occur

remains...

unexplained.

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