All language subtitles for Through.the.Wormhole.S05E06.Is.a.Zombie.Apocalypse.Possible.720p.HDTV.x264-DHD

Freeman: It is a nightmare that
has stalked us for centuries.

Hordes of human beings
transformed

into mindless,
bloodthirsty monsters,

and civilization collapses.
[ Siren wailing ]

Could this nightmare
become reality?

Scientists have discovered
parasites that turn the living

into the walking dead,

and new strains of deadly
pathogens attack us every year.

Neuroscientists are learning how
to take over our minds.

Will we someday lose control
of our bodies and souls?

Is a zombie apocalypse possible?

Space, time, life itself...

The secrets of the cosmos
lie through the wormhole.

♪ Through the Wormhole 05x06 ♪
Is a Zombie Apocalypse Possible?
Original Air Date on June 25, 2014

== sync, corrected by elderman ==
@elder_man

According to Haitian folklore,

certain priests
had magical powders...

[ Thunderclap ]
That could transform a corpse...

into a puppet.

Our popular culture has turned
that zombie legend

into an apocalyptic nightmare,

a contagious virus
that turns the infected

into violent monsters
with rotting flesh.

[ Thunderclap ]

We are all just one bite away

from joining the mindless
legions of walking dead.

All of these are myths,
of course.

[ Thunderclap ]

But every myth
has a grain of truth.

Could our imaginations

be telling us something
about our future?

[ Thunderclap ]

Freeman: A long time ago,

my friends and I saw a movie...
[ Door creaks ]

that gave us nightmares...
[ All gasp ]

"The Mummy."

[ Children screaming ]
In that story,

ancient magic made a corpse walk
the earth again.

Could such a mindless monster
ever exist in the real world?

David Hughes is an entomologist.

He has a long history

with the dark side
of that science.

When I was a kid

I had a rather personal
relationship with a fungus.

We didn't know exactly
what it was at the beginning,

and over the course of months,

this fungus creeped its way
across my scalp,

uh, making me half bald.

Freeman: David survived,

but his fungus was not the worst
nature has cooked up.

Some funguses turned the bodies
of their hosts into piles of rot

and enslave their minds.

David is the foremost expert
on a fungus

that turns its victims
into the walking dead,

or to be more accurate,
the crawling dead.

The fungus, like all organisms
on the planet,

has a scientific name.

This one's called
ophiocordyceps unitlateralis.

But colloquially, it's known
as the zombie ant fungi.

Freeman:
While foraging for food,

an unsuspecting ant

will pick up a spore
of the zombie fungus.

The fungus bores
through the ant's body.

It multiplies and infects
the ant's brain,

where it releases

powerful mind-controlling
chemicals.

The zombified ant bites
the underside of a leaf

and dies.

Well, sort of.

Death is really the starting
point for the parasite.

Fungi are rather interesting

in that they require
the host to die,

and then, from its tissues,
they grow and they reproduce.

And so, at this stage,

the whole ant body
is completely transformed.

Freeman: The zombie ant fungus
continues to control

the dead creature's mind,

keeping the insect's jaw
locked onto the leaf.

The fungus multiplies,

building pressure
inside the ant's skull

until...it breaks open.

Out comes a fungal stock
that sprays down deadly spores

on the fungus's next victims.

The cycle repeats.

The fungal spores need to be
shot out, launched,

from an area high above
the foraging trail.

And so the fungus
has evolved the ability

to control the mind
of its host.

Freeman: Inside their nests,
ants are hygienic.

But when they're out foraging,

they are vulnerable
to infection.

David believes the fungus
evolved the ability

to strike the ants
during this moment of weakness.

The zombie ant fungus
could never infect us.

Our brains are too different
from those of ants.

But could a similar pathogen
ever find its way into our mind?

So fungi have clearly
evolved the ability

to control the behavior
of animals.

Our brains are animal brains,
and there's no reason,

theoretically, why we couldn't
have our behavior controlled.

Freeman: If a mind-enslaving
pathogen ever strikes humanity,

it will most likely jump to us

from our close genetic
relatives.

Microbiologist Kartik Chandran
studies the Ebola virus...

A pathogen
from our worst nightmares.

Within weeks of infection,

most patients leak blood
from every orifice and die.

Kartik is leading a team
to find out

how deadly viruses like Ebola
evolve to infect humans.

As far as we know,
Ebola lives in bats,

and every once in a while,

this virus can break out
from bats into other animals,

including primates and apes
and humans.

Freeman:
Kartik is investigating

how Ebola made the jump
from bats to us.

He's imagining what it's like

to be one
of the microscopic bad guys.

[ Static, door creaks ]

The human body is a lot like
a building

where our cells are rooms.

Viruses infect us
by breaking and entering.

So you might ask me,
why does this little room

in this storage facility
have a lock?

And so the answer
is obvious --

because somebody needs
to go in and out.

This is an attempt
to secure the entrance

so that only the authorized
individuals can get in.

And cells are the same way.

You know,
cells need to bring stuff in,

they need to export stuff,

and viruses have really
evolved to exploit

this sort of entry
and access ways.

Freeman: Viruses mimic
the shape of nutrients

that the cell needs to survive,

just like a lockpick
mimics the shape of a key.

[ Click, door rattling ]

Freeman: Once inside the cell,

the virus inserts
its malicious genetic code.

The host cell becomes
an enslaved factory,

producing countless copies
of the invader.

[ Screeching sound ]

A multiplying virus can build
so much pressure

inside the host cell
that it explodes...

[ Explosion ]

...ejecting millions of viral
clones to infect other cells.

For a virus to jump
from animal to human,

it has to find a piece
of biological machinery

shared by both the animal
and the human cell.

Like you often see with
viruses and other parasites,

they evolve to co-opt these
common cellular mechanisms,

and Ebola has done
just that.

Freeman: Kartik made
a groundbreaking discovery.

Ebola relies on a protein
called npc1 to infect cells.

NPC1 is found in both bat
and human cells.

[ Chirping ]

Bats and humans may seem
very different,

but their cells use remarkably
similar molecular machinery.

Most viruses that infect bats
can also jump to humans.

All a virus has to do
is find those common keys.

So, I mean, I think
it's a probability thing.

The more closely related
you are to another organism,

the more likely you are
to pick up a virus.

Freeman: A virus that turns
human beings

into violent, unconscious
monsters already exists...

Rabies.

People that have rabies

go through a phase where they're
highly violent and belligerent,

and they can foam
at the mouth.

These are changes that are --

clearly seem to benefit
the virus

in terms of its ability
to spread

from one infected host
to a naive host.

Freeman: A rabies infection

does not spread easily
from person to person.

But if a virus like rabies
mutated

to have
influenza-like properties,

it could spread like wildfire.

[ Coughing ]

Freeman: The infected would
mistake it for a common cold...

...until it's too late...

[ Coughing ]

Freeman: ...and they fall
into a mindless rage.

They would become violent
and attack without warning.

[ Strangled yell ]

[ Stabbing sound ]

[ Panting ]

[ Gasps ]
[ Banging on door ]

Freeman: Open wounds
would benefit the virus.

It would easily transmit
through airborne particles.

[ Elevator bell dings ]

Ironically,
our own vigilant immune systems

could help bring this virus
into existence.

Once a virus infects a cell,

there is sort of this hardwired
immune response

that makes all these
new machines in the cell

that can try to stop the virus
from infecting,

and so the virus
has got to evolve

so it can get around these
sort of antiviral proteins.

Freeman:
In the never-ending arms race

between the virus
and the host's immune system,

both sides
keep upping their game.

As viruses mutate, they develop
an array of evasive talents.

In some mutations, viruses learn
to become invisible.

[ Switch clicks ]

Other times,
they evolve chemical tools

that allow them to disable
the body's infection monitors.

[ Static ]

Or if the virus
mutates just right,

it can permanently evade
the immune system with a decoy.

Eventually, a new form
of the virus will evolve

that can slip
past the body's defenses.

And that virus is selected
because it's the only one

that's able to grow
and replicate itself

in these cells,
and so, all of a sudden,

it takes over
the whole population.

So you go through these sort of,
like, bursts of selection

that completely change the --

sort of the structure
of the viral population.

And this can happen
very quickly.

Freeman: As long as we rely on
our immune systems

to keep us healthy, new viruses
will constantly evolve.

But a zombie virus may also

one day be created
in a laboratory.

We should be able
to design viruses

that do different things.

In principle,
it seems to me

that if you know what
buttons to push,

you could make a virus
that could do those things.

Freeman: Kartik, of course,

wants to stop a zombie virus,
not create one.

But nothing is preventing
the wrong minds

from pursuing it.

Is a zombie virus possible?

I mean, I suppose there's really
nothing in the laws of physics

that says it's impossible,

although I would say
that it could be

some sort of combination

of different viruses
that we know about.

Freeman: A hybrid virus
that turns human beings

into deadly, contagious monsters
is not likely,

but it is possible.

It could come from a laboratory,

or could be born
from the crucible of evolution.

If this virus breaks out,
what happens next?

When you get the flu,
what do you do?

Go home, get in bed,
and hope no one bothers you.

But imagine a disease
that spreads

by making its victims violent.

Such a disease could emerge
someday.

Could we keep it from becoming
a global pandemic?

In Ottawa, Canada,

a scientist is taking on
the zombie apocalypse

before it happens.

[ Beeps ]

A scientist who always seems
to have a question on his mind.

I added the question mark
because my name was very boring,

and I was getting confused
with all kinds of Robert Smiths,

so I thought it'd be
a cool thing to add to my name.

And because I have
my question mark which helps me

be distinguished
from other Robert Smiths

in my specific field of
disease modeling by mathematics.

Freeman:
Diseases are everywhere.

[ Coughs ]
Robert wants to log

every moment in his life...
[ Cell phone rings, beeps ]

When he can pick up a pathogen
from an infected person,

even when the infected
aren't around.

[ Water streaming ]
If a disease is airborne,

then the air that we share

is obviously something that's
potentially quite toxic.

[ Cell phone rings, beeps ]
And the closer you are,

of course, the more likely.

But then other things become
transmissible as well.

So doorknobs and, you know...
[ Cell phone rings ]

[ Beep ]
The handle of whatever it is

that I'm touching
or breathing on.

[ Cell phone rings ]

[ Beeping ]

Freeman:
Robert is using this data

to build mathematical models
to predict

how quickly infectious diseases
can spread.

And with the help
of his students,

he's creating live
human versions of those models.

Just like any human community,

the virus has many chances
to find a new host.

Okay, in these beakers, most of
them are just plain water.

One of them has been infected

with something that's gonna
simulate a virus.

Freeman: The rules are simple.

No student can take more
than five steps.

Ready? And go.
[ Blows whistle ]

Freeman:
They have 30 seconds to mix

with as many other students
as possible,

and no one knows
who has the beaker

with the infection.

Robert wants to see how many
people patient zero can infect.

[ Toot ]

Okay, now please return
your beakers to the middle.

Freeman:
At the end of the game,

Robert drops a chemical
into each beaker.

If a student mixed
with the infected,

their water will turn yellow.

Even though patient zero

could only have direct contact
with a few neighbors,

those neighbors
passed the disease along,

and about half the group
ends up infected.

But Robert believes the math
desperately needs an update.

So recently,
we tried to update models,

and we have much more
powerful ways of understanding

the network of connections
that different people have.

[ Film projector whirring ]

Freeman: The old models
focused on human beings

and their local communities.

But we now live
in a global society

and are on the move
like never before.

On an average day,
approximately 22.8 million of us

travel someplace far away.

Robert repeats the game
with the same rules,

but this time,
the students are allowed

to take as many steps
as they wish

to account for the ease
with which we travel.

[ Toot ]

[ Toot ]

Freeman: At the end
of the 30-second round,

Robert tests each beaker again.

Every student is infected.

Robert has calculated

the infection rate for a disease
that doesn't yet exist.

He imagines a virus that spreads
easily through the air,

like the flu.

But unlike influenza,

the disease does not make
its victims

want to stay home in bed.

Instead, they become zombies,

and they take to the streets
in a mindless rage.

[ Snarls ]

So if we actually had
a zombie virus,

then the mathematics predicts

that we're not gonna do
very well.

[ Sirens wailing ]

Freeman: If just one person is
infected with this zombie virus,

Robert predicts an epidemic
is inevitable.

Cities would be overrun
in weeks.

[ Crowd shouting indistinctly ]

Freeman: As refugees escape,

some of them inadvertently
bring the disease along.

Global civilization
as we know it

would be brought to its knees
in a matter of months.

We have completely eradicated
only two infectious diseases --

cattle plague and smallpox.

Finding a cure for this
hypothetical zombie virus

is very unlikely.

But if a zombie outbreak
does happen,

Robert's calculations

show how humans can avoid
total annihilation...

by getting our hands dirty.

Probably the best way that
we found to deal with zombies

was to basically hit them hard
and hit them often.

So the idea is that you try and
wipe the zombies out in one go,

and of course, you're not
gonna be successful at that,

so, next day, you try
and wipe them out again,

using the knowledge that you
learned from the last time.

So we get better at it,

and so then the third day,
we're now even better.

Freeman: To stop a zombie plague
from becoming an apocalypse,

we may only have
one horrifying option --

to kill
every single infected person.

Just one surviving zombie
could trigger another epidemic.

Our best hope to stop
a super virus

is to catch it in time.

Virus hunters are
scouring the microscopic world,

looking for
an invisible enemy

that may have already made
its first move.

During the four years
of World War I,

almost 15 million people died.

In the two years that followed,

a single flu virus claimed
three times that many lives.

The virus had spread
around the world

before anyone detected it.

There are millions
of microbes out there,

most of them harmless.

How can we find
the next deadly pandemic,

perhaps a zombie virus...

[ Imitates gunshot ]

...before it sweeps the globe?

[ Blows air ]

[ Wind blowing loudly ]

Hello?

Hello?

Freeman:
According to Ian Lipkin,

the world's leading
virus hunter,

our civilization runs a terrible
risk of global pandemic.

I'm standing in the middle
of Times Square,

and it's completely deserted.

It looks like something that
you might see in a movie,

but, in fact,
it's a real possibility.

Freeman: Ian is the director

for the Center
for Infection and Immunity

at Columbia University.

His team is on the front lines,

hunting for deadly viruses
before they become pandemics.

In 2003, his lab was the first

to identify
the lethal S.A.R.S. virus.

That early discovery saved
countless lives.

Nature herself is continually
evolving new bacteria,

new viruses
that are more pathogenic,

that escape the antivirals,
the antibacterials,

the vaccines that we create
to hold them in check.

[ Coughs ]

Freeman: There are more

than 10,000 trillion trillion
trillion viruses on earth.

Pinpointing a deadly virus
in a sea of its benign cousins

is just about impossible,

unless you lure the virus
out of hiding.

When a patient falls ill
somewhere in the world

with an unknown virus,

blood
and other biological samples

are often sent to Ian's lab.

He then gets to work
by going fishing with D.N.A.

D.N.A. makes
for the perfect virus bait,

because viruses contain
genetic code

that binds to matching sequences
of D.N.A.

So then if that virus
is present within that sample,

it will be caught on the hook,

and I'll be able to reel it in,
and I'll see it.

Freeman: Ian can cast thousands
of genetic lures

into the sample.

Each one is tailored to attract
a known virus.

[ Screeches ]

Freeman: Biological samples
from sick patients

are oceans filled with microbes
that ignore the lure,

except for the virus
that is a match

for the lure's D.N.A. sequence.

The virus lines up
its genetic code --

A binds to T,
C binds to G.

Once it's hooked...
Uh-oh.

The weight of the lure changes,

and Ian can reel in the virus.

[ Seagulls crying ]

[ Click ]

Now, if that method works,
then we can get an answer

very, very quickly,
very inexpensively,

probably in a matter of four
to six hours at the outside.

Freeman:
But viral and genetic code

can evolve rapidly.

Sometimes new viruses
have changed so much

that they no longer
stick to the lure.

In that case, Ian switches
to another technique --

grab all the D.N.A. he can.

I have a net.

This is essentially
a D.N.A. sequence.

When we don't know precisely
what we're looking for,

we use
a high-throughput sequencer

that allows us to characterize
all of the genetic material

that'd be present
within a sample.

We pull everything in,
and then we compare that

with a database
of all known sequences.

That allows us
to identify anything

which is potentially
a microbial agent.

Freeman: Ian and his team

then grow colonies
of the isolated virus

and attempt either
to identify a drug

that can fight the infection
or to develop a vaccine.

We and our colleagues can begin
testing drugs for efficacy,

drugs that will be able
to prevent this agent

from reproducing itself.

And then, ultimately,

because drugs are frequently
too expensive,

we try to collaborate
with people

who know how
to develop vaccines.

Freeman: No matter how quickly

they identify new viruses,
however,

there will always be a lag time
between detection and treatment,

a time
when the virus can spread.

The major time lag is not
at the level of the laboratory.

It's really in the field.

It's recognizing the appearance
of something as new.

Then that has to percolate

through the ether until
it reaches people like us.

Freeman:
Ian's team could prevent

millions if not billions of us

from succumbing
to a highly infectious disease.

But if a virus evolves
that is sufficiently different

from the viruses we know today,

Ian's team will not be able
to fish it out.

[ Beeping ]

In humanity's war on viruses,
we need a new strategy.

We can hunt viruses down,

and we can try to vaccinate
ourselves against them.

But once they infect us,
we're at their mercy.

What if we turn a virus
into a zombie

that works for us
and make it kill a zombie virus?

Modern medicine

has conquered many diseases
in the past century.

Viruses, however,
remain elusive targets.

Because they hijack the vital
genetic machinery of our cells,

killing them is tricky.

The solution may require
a pair of these,

shrunk down to the size
of our D.N.A.

[ Snip ]

Viruses are party crashers.

They do everything possible to
blend in with healthy cells...

Aah!
[ Snarling ]

Freeman: ...All the while

relentlessly infecting
the invited guests.

For severe infections,

our best medical treatments
today are crude.

They work by chopping up
the harmful invaders...

Party's over.

[ Motor revs, women scream ]

[ Saw buzzing ]
...And all the healthy cells

in their vicinity.

But a new treatment that
only goes after the bad guys

could be
right around the corner.

As the director
of the Center for Nanomedicine

at U.C. Santa Barbara,

Jamey Marth
thinks it should be possible

to make an antiviral drug

out of a class of chemicals that
we all have in our stomachs.

The food that I have
on this plate right now

is what I need to keep me alive
and mostly healthy.

[ Crunching ]

But for my body
to use this material,

it has to convert it
into different forms,

and it does that by using small
natural machines called enzymes.

Freeman: Enzymes are
the power tools of microbiology.

In the stomach, they break apart
our food into digestible forms.

Jamey and his colleagues
are working

with an enzyme called
C.R.E. Recombinase.

This enzyme
has remarkable utility.

It can cut out any section
of D.N.A.

And neatly staple back together

the two adjoining
genetic pieces.

It's allowed us
to do things

that we haven't been
able to do before --

to remove specific genes
from specific cells

at different times.

Freeman:
Inside every cell in our body,

there is a forest of D.N.A.

Viruses sneak foreign genes

into this forest and hijack
our cellular machinery.

A drug based on Jamey's
C.R.E. Recombinase enzyme

could chop down viral infections
at their root

by weeding out their D.N.A.

The enzyme needs to find
a specific sequence

of 34 genetic letters
at either end of the cut.

And that sequence
can be customized.

So once you know
the genetic sequence of a virus,

you can program
C.R.E. Recombinase

to latch onto the first and last
parts of this D.N.A. code.

This represents
viral D.N.A. --

D.N.A. that's foreign
to the cell

and has integrated itself
into the genome.

An enzyme like
the C.R.E. Recombinase

is capable
of removing this precisely

from the cell's genome.

It does this
with precision.

[ Snip ]

And then, what the enzyme
will do

is it will stitch
back together

the ends
of the normal D.N.A.

So that the cell is
effectively cured...

[ Stapler clicks ]

...of the disease.

Freeman: Jamey is laying
the groundwork

for what could be a cure
for all infectious viruses.

H.I.V. A.I.D.S...

[ Snip, click ]

...influenza...

[ Snip, click ]

...even the common cold...

[ Snip, click ]

...will all only exist
in history books.

And the delivery vehicle
for this life-saving drug

is the last thing
you would expect --

another virus.

We could reprogram that virus
so that once that virus

binds and goes
inside the cell,

instead of releasing
a disease-causing payload,

it will instead release
a cargo

that allows us
to cure those cells.

[ Screaming and crying ]

Freeman:
Our best weapon against a virus

that turns humans into zombies

could be a virus that we turn
into our zombie slave.

[ Roars ]

Freeman: This harmful virus

would be stripped
of its disease payload

and instead be filled

with reprogrammed
C.R.E. Recombinase enzymes,

which can search throughout
our entire bodies

and only eliminate
the unwanted invaders.

[ Clinking ]

But finding a universal cure
for viruses may not save us

from a world
filled with zombies.

A zombie takeover is already
underway in a lab

in North Carolina,
where living creatures

are turned into zombie drones
at the press of a button.

If I told you
to run off a cliff,

you wouldn't do it, would you?

But what if I took control
of the neurons in your brain

and made your legs
run straight off the edge?

Turning a conscious person
into a mindless zombie

may only be a matter
of finding

and controlling
the right circuits in the brain.

[ Electricity crackling ]

[ Chuckles ]

How do you get a living mind to
completely surrender its will?

Electrical engineer
Alper Bozkurt

thinks we've been doing it
for centuries

by domesticating wild animals.

The horses open themselves
to our control

thanks to this mutual beneficial
relation that we have with them,

and it took a long time for us
to be able to train them,

uh, basically
to condition them

with different rewards
or punishments.

Freeman: Alper looks at animals
as electrical circuits.

As a horse moves,

its brain sends

an elaborate series of commands
to its muscles

through the electrical wiring
of its nerve cells.

[ Electricity crackling ]

But convincing a horse
to make these complex movements

only requires a simple input.

So when the rider wants
the horse to go to left,

she just pulls
the reins to left...

[ Nickers ]

...and the horse starts
going in that direction.

And then, she wants it
to go right.

She just pulls it to right,

and we see that horse
is going on the right.

[ Nickering ]

And then
she wants it to go forward.

She just provides
a gentle kick with her heels,

and the horse knows
that it needs to go forward,

and it does it.

[ Blusters ]

Freeman: The horse obeys
because of its training.

But Alper thinks he can get

the same results
in other creatures

without conditioning
by replacing mechanical commands

with electrical signals
sent directly to the brain.

I have a set
of domino stones here

representing a neural network
like in any brain.

A brain is a set of
electrical relay networks.

It is composed of excitable
cells called neurons.

Freeman: When neurons
become electrically excited,

they pass a signal
on to their neighbors,

which in turn
pass the signal along.

Alper only needs
to stimulate one neuron,

and the entire neural circuit
will activate,

resulting
in a complex bodily action.

It's a principle that should
work in any brain,

but Alper is starting
with a simple mind --

the cockroach.

Alper implanted electrodes
into the sockets

where a roach's antennae
connect to its brain.

[ Clicking ]

When he sends an electronic
pulse to the neurons inside,

the roach becomes...

a zombie.

It goes wherever
the electronic pulse

tells it to go,
and it even turns on a dime.

So when we stimulate
the right antenna of the insect,

insect thinks there there's
an obstacle in front of it,

and it tries
to make a left turn.

And when we stimulate
the left antenna,

it tries to make
a right turn.

Freeman:
Alper thinks his zombie bugs

will one day save lives.

He envisions cockroach cyborgs
outfitted with cameras

and G.P.S. chips

so they can locate survivors
under collapsed buildings.

But his breakthrough could be
the beginning of a world

where no mind is safe.

Theoretically, even a human
could be zombified.

We know how neurons work,

and, uh, we can communicate
with them.

When we stimulate the insect,

it is the same stimulation
principle

that is used in deep brain
stimulation patients

with Parkinson's disease.

So these are all
the same principles.

It's relatively easy
with cockroaches

to make them follow
our command signals.

But with higher organisms,
with vertebrates,

it is much complicated,
although it's not impossible.

Freeman: Technology may soon
exist that, in the wrong hands,

could turn us into zombies.

If our minds are taken over,
will we even know it?

A zombie apocalypse may already
be happening today.

In fact,
this neuroscientist thinks

we're already 98% zombie.

In fiction,

the nightmare
of a zombie apocalypse

is constantly taking on
new forms,

but they all have
a common theme --

the infected don't even know
they are zombies.

If, right now, we were zombies
in the midst of an apocalypse,

would we even know it?

[ Birds chirping ]

Neuroscientist Scott Grafton

believes
that in sports like golf,

it pays to be a zombie.

I was watching
this tournament

where Fuzzy Zoeller
was winning.

[ Whack ]

Announcer runs up to him
and says,

"Fuzzy, how did you do it?
How did you win?"

He says, "Well, I've been
brain-dead all week."

[ Whack ]

Freeman: After enough practice,
a good swing is automatic.

In fact, nearly everything
that our bodies do

requires little,
if any, thought.

Almost all of our actions
are actually unconscious.

We can pretend we access
our muscle.

You know, when I hold
a golf club,

I can grip it,
and then I can think,

okay, flex this muscle,
extend this muscle,

turn my shoulders,
turn my waist, so forth.

But actually, I have very, very
poor access to those muscles.

It's much easier to visualize
what you'd like to happen,

and the swing
just takes care of itself.

[ Whack ]

Freeman:
Our brains are goal-oriented.

We think of an end result,

and our bodies mindlessly follow
a program to achieve it.

Freeman:
For Scott, this is evidence

that our willpower
is not as strong as we think.

On a good day, I think
we're about, uh...97% zombie,

and on a bad day, 98% zombie,
and the rest of the 2 or 3%

is us having actually
willful control

over our daily activities.

Freeman: Scott is running
an experiment

to momentarily rob his subject,
misty, of the other 2%.

He uses a technique

called transcranial magnetic
stimulation,

or T.M.S., to induce

a harmless electrical current
in her brain.

[ Click ]
Oh.

T.M.S. is a method for

very briefly turning off
a small part of your brain,

so it's a copper coil
that goes against the skull,

and you induce a current
through that,

and during that time,

you essentially have a virtual
lesion in your brain.

[ Clicking ]

Freeman:
Scott calibrates the device

by stimulating the neurons
that control her right hand.

He then moves the device to
focus on her parietal cortex.

This region of the brain
is believed to be responsible

for making sure that our actions
match our intentions,

like trying to touch
an illuminated dot.

In the first round
of Scott's experiment,

there is no T.M.S. pulse.

As soon as their hand
starts moving,

we jump that second light
to the right a few inches,

and their hand quickly
corrects for that jump,

and it smoothly goes over
and pursues that new location.

Freeman:
But in the second round,

right as misty's finger moves,
Scott zaps her parietal cortex.

Oh.

Freeman:
She doesn't feel the pulse

but loses the ability
to consciously

correct her action
for a brief moment.

They react, essentially,

as a zombie and go
to the original location,

that second light,

and they're unable to correct
themselves on the fly.

So when we turn off
the parietal lobe,

we're essentially
making a person a full zombie

for just a second or so.

And during that time,

they're just carrying out
a movement

that they no longer
can control.

Freeman: Scott believes
we evolved to be 98% zombie

so that the intellectual parts
of our brains

could be freed up from thinking
about the menial tasks

that take up most of our time.

For all of
its evolutionary advantages,

the intelligent human brain
may come with a cost.

I think we're a hair's breadth
away from a zombie apocalypse

in the sense
that most of what we do,

we can accomplish
without thinking about it.

Just think about
how many willful choices

you've made
in the last week.

It's probably
maybe one or two.

Everything else you did was
essentially automatic behavior.

So now you think of something,
it takes away that last 2%.

You're already prepared
to live as a zombie.

Freeman: By the time
we reach adulthood,

most of our daily lives
are spent engaging

in activities that require
little conscious thought.

If we were to lose our ability
to make conscious decisions,

life just might continue
as normal.

Certainly, we wouldn't
recognize it in ourselves,

and the scary thing is whether
you could recognize it

in anyone else.

If there was
a zombie apocalypse,

I don't think it would be
like "World War Z."

I think we would be
plain old normal human beings,

except we'd be
a little bit different.

We'd be more like "invasion
of the body snatchers,"

where we're ourselves, but we're
not ourselves anymore.

We humans love our free will.

As bizarre as it may seem,

it is entirely possible
that a microscopic parasite

or technology run wild

could take away the free will
we cherish so dearly.

All of this talk
of zombie apocalypse

raises one final question --

why do we enjoy scaring
ourselves half to death?

Maybe that's what we need to do

in order to prepare
for the worst.

I'm not scared, because science
is our best defense.

== sync, corrected by elderman ==
@elder_man