Original subtitles

- Hidden on you is a world you have never seen

overrun with bizarre creatures that live on and in

every part of your body.

- It's an animal.

It's on your face and we don't know very much about it.

- Yet they are affecting us

in ways we never imagined

but now for the first time

we can explore this unknown world.

- They're an absolutely essential component of what we are.

- This is a struggle of life and death.

- If we got rid of all of the microbes on us

and inside us we would die.

- So doctors are even reintroducing bugs into our bodies.

- Larvae are alive.

They're going through the skin.

It's Judy plus hookworm.

(laughing)

- You are more than human.

Each and everyone of us is a collection

of different life forms that call us home.

This is Life on Us.

(dramatic orchestra music)

(bouncy flute music)

You are mostly not you.

- Come on.

- You are home to an astounding array

of life forms.

Some creatures hide inside your bowels.

Others prefer the view from your eye brows.

There are gardens of fungi on your feet.

Alien tribes inhabit the jungle of your hair.

Tiny mites borrow into your face

and you host more bacteria

than there are stars in the milky way.

You and your bugs form a web of life.

In fact bugs are us.

(baby crying)

Everyday this typical family is home

to 100 trillion hitchhikers

on their skin and inside their body.

(baby laughing)

These invisible colonizers keep them healthy.

Sometimes make them ill.

- Hey!

- Mine! - You played yesterday.

- No it's breakfast.

- And even influence their behavior.

- Wait!

- Stop fighting!

- Yet until recently we understood very little

about our microscopic residents.

(dramatic flourish)

Germs have a bad reputation.

We think of them as the cause of disease

but paradoxically we couldn't survive without them.

- We have our tunnel vision.

- Bacteria are bad.

The archaeans are bad.

All this stuff growing on me is bad.

Let's just nuke it.

- And the majority of those organisms

are actually good for us.

They're assisting us.

They're not our enemies.

- Our obsession with bad bugs

left us blind to the good,

but now genetic tools allow us to see

what we've been missing.

- Molecular tools, sequencing DNA,

have allowed us to get a true picture

of what organisms are there

and there's a far richer picture than we had previously

appreciated for our culturing microorganisms.

- By decoding the genes

of these microscopic creatures

we can reveal a new microbial world.

- The genetic tools are kind of like the new telescope.

- Think of it as a geographer that might have

just been studying the fields

around Norway their whole career

and then somebody says, "Oh by the way

"we just discovered the Americas and Australia,"

and nobody had ever heard of it before.

- For the first time we can see the microbes

that live on us and inside us.

- It's a bit like a gold rush at the moment.

- It really is a very thrilling thing.

- Scientists have embarked on a journey

into the unexplored world of our own body.

They are discovering how we are all shaped and kept alive

by the bugs that live on us.

As the crust covers planet Earth

the skin covers the body,

an impermeable barrier between us and invading germs.

(sirens wailing)

But we only realize just how important it is

when it's compromised.

- I see people's lives changed

in an instant on a daily basis.

But that tissue on the corner right

is not gonna stay.

- Fiona Wood is a world leading burn specialist.

Her struggle to save lives is all about beating pathogens.

The microbes that cause infections.

- We have bacteria and pathogens

all over us all the time.

When you have a breach in your skin there's a way in

and that way in is going to be there

until we seal the wound.

So the longer the wound is open

the greater the risk of getting infected.

So what we want to do is close that surface.

Seal the surface of the wound as quickly as possible

while the waves of infection keep coming over.

If you waterproof you will survive.

- And central to that survival

is the layer of microbes that live on our skin.

Like the atmosphere that protects our planet

our microbes form a shield against alien invaders.

- If some pathogen arrives on your skin

it's not your immune system that rises up to greet it.

The first thing that greets it is this microbial layer.

This hairy invisible cloak.

(water gurgling)

- But where do these bugs come from?

(triumphant orchestra music)

The answer lies in the miracle of birth.

(heart beating)

For the baby the womb is a solitary world,

but outside an army of microbes awaits its arrival.

(clock ticking)

(sirens wailing)

(heavy breathing)

(slow piano music)

(moaning and wailing)

(baby crying)

- The moment you're born you're colonized

with your mother's microbes.

Until then you can be called 100% human

but after that moment you're really

just 10% human and 90% microbes.

- Which as a scientist is very very exciting,

but as a parent is terrifying.

(baby cooing)

(camera shutters)

- Towards the end of pregnancy

the bacteria that live in the mother's gut

migrate to the vagina

ready for the baby to pick them up

as it slides through the birth canal.

(heart beating)

(baby crying)

Being covered in vagina microbes

may not seem much of a trait,

but it's a gift that lasts a lifetime.

These bugs not only protect us from infections

they're essential for our overall health.

- They also have an important role

in regulating the immune system.

(dramatic music)

- The immune system never rests.

Its cells constantly patrol our bodies

to eliminate pathogens,

but this power can also be dangerous.

- It can potentially damage your own tissues

and therefore it must be controlled.

It must be turned down.

It must be regulated.

- The immune system has an internal police force

keeping it under constant surveillance.

- If you don't have a properly regulated immune system

it becomes trigger happy.

It's attacking people's brains.

It's attacking people's joints and giving them arthritis

or it's attacking the contents of the gut

and then you have inflammatory bowel disease,

or it's attacking trivial quantities of pollen

or dog dandruff or whatever in the air

and that gives you allergic airway disorders.

- And what keeps our immune system in check

is our microbes.

- So that if you have that organism in the gut

you have more, more policemen.

More regulation.

More control of the immune system

so it doesn't get trigger happy and do crazy things.

- The supply of these microbial regulators

doesn't stop at birth.

The mother continues to deliver hundreds

of species of bacteria in her breast milk.

- And it's only very recently that it's become clear

that breast milk comes with a whole suite of microbes

that have moved up through the mother's body,

through the lymph, into the milk,

and come as part of what goes

into the baby with the breast milk.

- Breast milk also contains sugars

that the infant can't digest.

These are like fertilizer for the baby's

rapidly developing gut flora.

- And the breast milk becomes this really amazing example

of the way in which our bodies actually evolved

to help these microbes to the next generation.

(baby babbling)

- By the time a child is two and a half

it will have developed a fully mature microscopic community.

Collectively they're known as our microbiome.

(dramatic music)

They're as much apart of us as any of our own organs.

- We shouldn't think of them as a scary

part of our machinery.

They're an absolutely essential component of what we are.

- Every one of us is a finely tuned society

of many different life forms

relying on one another for survival,

but we're only just beginning to discover new species

in the most unexpected places.

This little bug could determine your health.

(enchanting orchestra music)

(birds chirping)

The Earth holds some spectacular habitats

and some retain their mystery,

but we know much less about the eco systems of our own body.

Parts of the body are wet.

Others are dry.

(squishing)

Some are hot and dark.

Others are cold and exposed to light.

We are a world of different climate zones.

(birds chirping)

(dramatic music)

And just as on Earth,

on the human body too

life adapts to the environment.

- I started work in tropical forests

and every process I could study in a tropical forest

is happening on my body and your body right now.

You have species that are plants.

You have species that eat those plants

and you have species that eat those species.

You have species that are predators.

You have species that are parasites.

There's active competition just the way that tree roots

grow against tree roots

or ant colonies grow against ant colonies

that same thing is happening.

- Rob Dunn's background in ecology

prepared him well for an exploration

of the wildlife of our bodies

and one of the most intriguing places

is the mysterious belly of smell,

the armpit.

- The armpit's this weird thing.

So why does it have hair?

Why does it smell funny?

What on Earth is going on with it?

- It is a pretty specialized environment.

It has high humidity levels

and there's human apocrine glands.

- And these are glands that don't really produce sweat.

They produce what I and other people think

it's actually a food for microbes.

It is an odorless food and is released

in incredible density out of your armpit.

(heart beating and breathing)

Armpits in and of themselves have no odor.

Your hair has no odor.

Most of your body has no odor.

Those odors are all microbial.

(upbeat jazz music)

- Bacteria thrive on the perspiration released

by our apocrine glands,

but they aren't active until we reach puberty

which is why babies smell sweet,

- Good morning.

- But teenagers don't.

So why are we feeling microbes in our armpits?

- We have hints.

We have parts of answers in other species.

Lemurs have these same glands

that kind of go across the chest

and in that case the lemurs seem to use them

for identifying each other.

Are you my cousin or not my cousin?

- Body odor helps the lemur

to determine if a prospective partner

is too closely related.

Sexual attraction is literally about chemistry.

Other mammals don't have their glands in their armpits.

They're around their anus and sexual organs.

- It looks like as we started to stand up more

and as we interacted with each other like this

that if we were gonna sniff each other

the hair and this smell had to move up.

- Meaning our armpits have a major influence

on how we date and mate.

It's not just muscles or bikinis

that brings men and women together.

It's the smell of our personal wildlife.

(heart beating and slow breathing)

Bacteria thrive in every nook and cranny of your body.

And one of the richest eco systems is your navel.

It's a tiny crater.

A scar that we carry through life

and we barely give a thought to it,

but for scientists at the

North Carolina Museum of Natural Sciences

the navel is a place of infinite mystery.

This is the home of the Belly Button Biodiversity Project.

Hundreds of volunteers have been recruited

to twirl a cotton swab in their belly button

to help find new species.

- Hi, how are you?

- The power of our research

comes from the fact that it will be able to sample

so many different citizens as scientists

and you kind of can't harness that power

unless people are engaged in a project.

- Welcome to the Daily Planet Theater.

- Brian Mellow bills himself

as a microbial comedian.

- We'll be talking about some citizens science projects

and about the life that lives on us.

We'll be talking about tiny life

which is really fascinating.

An infectious disease walks into a bar.

The bartender says,

"We don't serves infectious disease in this bar."

The infectious disease says,

"Well you're not a very good host."

(laughter)

If I can make you laugh maybe that'll

make you more open minded to the subject

and maybe it'll make it more memorable.

- And we want you to take this swab

and be really careful.

Just loosen it up, k?

Lift up, get it nice and good.

Get all the gunk out. - Anything getting on here?

- All the microbes out.

- Yeah so while that's happening you're actually getting

individual living organisms on that swab.

- Just by touching to it yeah.

- Not squirrels or anything,

but like bacteria, Archeanas, Proteus,

um, fungus - Dogs, cats.

- Yeah, dogs are really unlikely

although it is a deep belly button

so I can't, yeah. - Small dogs, chihuahuas,

- I can't rule anything out. - not Great Danes.

- I'm not looking, I'm trying not to look,

but we'll see it if it's on the swab.

- No I keep it clean.

I probably don't have anything in there.

(water running)

- In fact, the belly button

is crawling with life.

It's protected from the chemical warfare of soap

and it's usually covered up from the ravages of weather.

All of which makes it a prime candidate

for the discovery of new species.

- Twirl it good.

- For a long time it's been argued

that the tropical rain forest canopy is the last frontier

and it's true that we know very little about that canopy,

but we know no more about our own bodies.

- The belly button survey

has revealed previously unimagined species on our body.

One person was carrying a form of archaic life

only ever seen before in the

most extreme environment on Earth.

In deep ocean fence.

(slow orchestra music)

- What's interesting is that if we look

at bacterial diversity in the human belly button

we have a huge amount of variations

you know, among 60 individuals.

There was not one species of bacterium

that was found in all 60 of those individuals.

- Like our retinal patterns,

fingerprints,

and our DNA,

the wildlife in our belly button is unique.

It's our microbial signature,

but it's in a constant state of flux.

The places we go

the food we eat

the people we meet

they all affect our microbial jungle.

- This is our Costa Rica, right?

This is our area where we go on the body

to really find our huge amount of diversity.

Um, compared to the armpit that's certainly true.

- So far the North Carolina team

has identified 2,300 bacteria species.

That's four times the diversity

of all bird species in North America.

And this abundant harvest has come

from just 60 belly buttons.

- So on your body overall you have thousands of species.

Most of them are not named.

- Some people maybe have a lot less than others?

- Some people have hundreds of species

living in their belly button.

Some people have as few as six species

living in their belly button

and having fewer species is associated

with poorer health outcomes

and so it increases your odds of getting sick.

- Maybe the words bacteria, microbes,

they have all sort of negative connotations to most people

so maybe they need a re-branding.

- Diminutive super friends.

(laughing)

- Just as we need biodiversity

to support life on Earth

we need a variety of microorganisms

to guard the health of our human ecosystems.

(bouncy flute music)

(water splashing gently)

On each square centimeter on your skin

there are more than a billion bacteria.

For them, it's a land of abundance

with plenty of food supplies.

(razor scraping skin)

You shed 30,000 to 40,000 dead skin cells every hour.

That's two kilograms in a year.

- Part of what they're consuming

is our dead skin, our dead bits,

and so there's some decomposition happening there.

They're at war with each other

and so even our good bacteria

are actively fighting each other

producing antibiotics.

They're all trying to win.

I mean, none of them want to just

be confined to our armpit, right?

Each and every species, they would all benefit

if they could colonize us from head to toe.

- One of our microscopic residents

engaged in chemical warfare is Bacillus subtilis.

They patrol the skin looking for fungi to attack.

Without them we'd wake up covered in mold.

Other microbes like Staphylococcus epidermis

colonize our skin in numbers so vast

that there is little room for invading rivals,

but the true power of bacteria comes when they act together

and this coordination requires a special language.

- Their genes are encoding proteins

that are allowing them to talk with each other

and to detect each other

and to control each other's growth

and basically to allow other bacteria

that are more beneficial or less competitive with them

you know, to grow in greater abundance.

(slow rock music)

- By tapping into a cell to cell network

microbes conspire with their own species

and build alliances with other bacteria

to outsmart invaders.

Bacteria are the most successful organisms on Earth

and part of their success is that they're able to steal

the genes they need to adapt and thrive.

- They're able to change their genomes very easily

and so this is why it's really important

to study the bacteria that grow on and with us and in us

to understand in a sense like what is the stable state,

because when a pathogen emerges

it's often one of these typical bacteria

that have co-evolved with us and have been

not a problem until ooh they picked up something

perhaps from a virus, from another bacterium,

who knows what?

And now they just change the game.

- This genetic flexibility

can transform our harmless microbes

from docile skin grazers into vicious killers.

- I suddenly felt very ill

and I went to the gentleman's toilets

and basically I collapsed on the floor.

- But how can a tiny bacteria

destroy a healthy body in just a few hours?

- Human or inhuman

not even the world's greatest scientific minds can answer.

- Gentleman do you realize?

Try the light switch.

- When good bacteria go bad

the result can be scarier than any science fiction.

(haunting music)

- For Andrew Ferguson a visit to an Alpine resort

became a life and death struggle with a rogue pathogen.

- I was vomiting and had blood coming out of my mouth

and nose and all sorts of strange places.

- On arrival Andrew had a quick swim

in the hotel pool.

Completely unaware that a rare skin bacteria

had already entered his body.

(ominous music)

- The bug, the Strep B bug, actually got in

through a cut on the leg and I was having a rigors attack.

It's actually where the body gets overwhelmed by bugs

and you go into a constant shaking

and I ended up at Garmisch-Partenkirchen Hospital.

Over the next 12 hours I must have had

every test known to man.

They just didn't know what the problem was.

Eventually after taking blood cultures

they discovered that I had a Streptococcal B infection

and then over a period of three days

I was given increasing dosages

of different types of penicillin,

but nothing was working.

- It's like being in a canoe

and going down the Niagara River.

If we're in it early enough someone can rescue us,

but if we're far enough down that river

eventually nothing is going to help us

and unfortunately that's the situation we have

with these invasive infections

where at the very last moment we have to get a surgeon

to get in and remove that destroyed tissue.

- The surgeon said, "We're probably gonna

"have to amputate the leg.

"The infection is spreading into a main artery

"and if we don't get it it's gonna go to your heart

"and you'll be dead."

I remember saying to the surgeon

as I went into that operating theater,

"I can do without the leg,

"but I certainly can't do without my life."

- Flesh eating disease

is an infection that literally eats its way

through the layers of tissue that surrounds the muscles

and it's fast.

It can cause death within 12 hours.

- It can spread amazingly quickly.

Sometimes we can even see it before our very eyes.

- This bug needs serious vigilance.

160,000 people are killed worldwide

by this bacterial onslaught every year.

- I still have my leg and um, as you will see,

I'm actually still have it.

The aftermath of all of this is

I have to take penicillin twice a day

and that has its implications as well

because unfortunately overuse of penicillin

tends to cause killing off the good bugs that sit in the gut

and then I ended up with other complications

as a result of that.

- These are dreadful infections.

To go from a perfectly healthy person one day

to dying or only being saved by very aggressive surgery

is an indication of these bacteria's potential

for harm to us.

- But what could turn Streptococcus,

usually no more dangerous than a sore throat

into such an aggressive killer?

Microbiologist Professor Mark Walker

was intrigued by the mystery.

- It was quite a surprise there being quite low levels

of very invasive diseases caused by this bug.

- With some ingenious genetic detective work

Professor Walker tracked the origin of the deadly disease.

- In the mid 1980's in the Rocky Mountain region

of the US there was an outbreak of flesh eating disease

caused by Streptococcus.

This outbreak was investigated and what was found

was that a new Group A Streptococcus

had come onto the scene

which was more virulent and better able

to cause invasive disease.

- This virulence was caused by a virus

called bacteriophage which invaded the strep

and modified its DNA.

- It inserts its genetic information into the bacteria

and that's the reprogramming that takes place

when a bacteriophage infects the bacteria.

- This modified bacteria was so successful

that the clone of that single bacterium

spread across the world.

(radio chatter)

- And in other news a young mother died.

- Hi - Hi, how are you?

- I'm Sharon Lewin.

Nice to meet you. - How are you?

- Tell us about what's happened to you

and what brought you to the Alfred?

- I arrived by ambulance.

I'm waking up from the anesthetic from the first surgery.

Being told that I've lost my small toe

and quite a lot of flesh from my foot.

- Did you have any injury to the foot

or it just, it just came out of the blue?

- It just sort of come out of the blue.

Like even the cut, the small cut that I had,

and then I've worked out recently talking to the doctors

trying to investigate more into this horrible bug

that um, basically you can get it from coral.

You can get it from dirt.

You can get it from potting mixes and things to my belief.

And I think I've got it through walking around my garden.

- Think we can have a look?

- Absolutely.

Get ready!

So that's the flap as you can see.

- Where's the flap here?

- The flaps come from the your whole top side of your back.

So I've got a massive scar from under my armpit

right down basically to my bum.

- Yeah, from here to here.

- Luckily the chance of catching such serious

invasive infection is still small.

- Usually we're able to live with these bacteria

within our throat or on our skin without getting disease.

So people should not be freaked out

the next time they have a sore throat

because that's just a normal event

and our immune system is able

to deal with it very adequately.

- But for those who cross paths

with the mutant form, Streptococcus can be fatal.

(lighthearted music)

Most of the wildlife on our bodies is harmless.

Even if we might horrified to discover

what they get up to.

Meet the tiny parasitic mite called Demodex.

It takes up residence in your eyelashes

burrowing head first into your pores.

- They're these long sort of narrow things.

They come out at night when you're sleeping.

Come out onto your face and have sex

and then crawl back into the pores.

It's an animal.

It's on your face and we don't know very much about it.

That's enough for me.

- Rob Dunn's meet your mites project

is trying to shed light on one

of our most overlooked hangers on.

- We can ask questions like how do the mites

in one human population relate to those

in another human population?

Pacific Islanders, they have different mite species

as a function of the relatively long isolation

from other people's.

Aboriginal people's of Australia,

what do their mites look like?

How have these mites changed as our faces have changed?

It's super exciting.

People get to see whether or not they have mites.

People get to see what they look like.

- Let's take those glasses off

because we're gonna try to get in your sort of t-zone.

- What if you're wiping the mites off right now?

- Well you know I don't think so

'cause I think they like to clink tight

to deep inside the pores on your face.

- That's always good to know, they're clinging tightly.

- They're clinging on.

I think 'cause they like to live in the oil

in your sebaceous glands

- Oh. - And so

it just feels like home.

- Good oil out here.

- Yeah, exactly. - Come and get it.

- They eat oil from our pores.

It'd probably eat microbes.

They probably have a pretty specific suite

of microbes in their guts which are just

you know, little hints about what's going on there.

- Apart from eating, crawling,

and having sex on your face while you sleep

Demodex may be linked to a common skin problem,

rosacea.

- The connection hasn't really been well defined,

but one of the hypotheses is that

is the bacteria inside the mite

that is what's causing the flare up of the rosacea.

- I'm prone to rosacea.

- Oh. - So if there's

a connection between mites and rosacea

lucky for you, I'm having a flare up right now.

(mite clicking)

- But it's not the mite that's the problem.

Like a Russian doll, there are bugs within bugs,

and in this case they have no way out.

- So it turns out that mites do not have an anus.

They have no exit.

- So they eat and eat and eat

and the feces just accumulates in their back end

and eventually they sort of fill up

and then it's all over.

You know, we thing about what our fate is determined by.

I'm grateful my fate is not determined by

how long it takes me to fill out with shit.

- As it turned out

Brian's face mites have made

a significant contribution to science.

This is the first time mites

have ever been filmed giving birth.

They too are part of our private wildlife.

- The truth is, is you're not really separate

from these critters.

Like who you are is defined by your interactions

with other species.

- What would we be without them?

- Yeah, what would we be without them?

And who are we when we have bad species on us?

So for example to take a really extreme example.

A Toxoplasma gondii is this Proteus that gets into the brain

and when it gets into our brain

it changes what happens in our brain.

(game beeping)

- Toxoplasma gondii is a cunning parasite.

It's a real life zombie bug and it's unmasking

is one of the strangest stories in science.

(birds chirping)

(suspenseful orchestra music)

Normally a self respecting mouse steers well clear

of anything that smells like a cat,

but for mice infected with the zombie bug

cats are like a magnet.

Mice pick up Toxoplasma from soil,

but to reproduce the parasite has to find its way

into the intestines of a cat

and the best way to meet up with a cat

is to alter the mouses natural fear

and make felines fatally attractive.

The brainwashed rodent is now easy prey,

but it's Toxoplasma that's the real winner here.

Once inside the cat it can reproduce.

(grass crushing)

The trail of the zombie bug led to Prague

and one of the world's oldest universities.

Professor Jaroslav Flegr is a renowned specialist

in the study of parasites.

By a complete coincidence

just as he was looking for a new subject to study

he was tested for Toxoplasma and the result was positive.

- I was not very happy to be infected by some parasite,

but uh, at the same time it was very

hmm

interesting.

I mean this idea that it can explain

some behavioral pattern of me.

- Normally Flegr was a cautious person

but he began to exhibit some very risky habits.

Not unlike the mouse who is attracted to cats.

- For example I'm not very afraid in situation

when I should be afraid.

It's a

very strange behavior.

For example I was in Gorjestan

and there was a lot of shooting around

and I was quite calm.

And it's not the only situation.

Also my startle reactions are a little bit unusual.

When somebody hits the horn behind me in some traffic

I stay in the same place, look slowly behind,

what has happened?

- Before Flegr no one ever thought

of linking human behavior to Toxoplasma infections

and if Flegr's hunt was right

it was messing with the brains of many other people as well.

- I started to study this hypothesis

on the cheapest material which is available here.

I mean on our students

and 25% of them were Toxoplasma infected.

- These studies show that those infected

by the zombie bug were far more likely

to put themselves in risky situations.

- The risk of traffic accident

of Toxoplasma infected subject is about 2.6 time higher

than the risk of traffic accident of non-infected.

- The implications of this discovery

are unsettling.

Toxoplasma is one of the most common human parasites.

- We used to think that our mind is really our,

but our results show that maybe it's not true.

- We can be infected

by eating unwashed vegetables

and under-cooked meat.

(speaking foreign language)

In some countries it's rampant.

In France where barely cooked meat is popular

infection rates are as high as 55% of the population.

So the next time you meet a reckless French driver

beware, it may be a zombie bug behind the wheel.

(upbeat French cafe music)

(tires screech)

(dramatic music)

- The hair on your head

is the equivalent of a rain forest.

Shaded, moist, and rich in nutrients.

It's the home for an annoying little critter,

the head louse.

- There are really interesting evolutionary stories

going on in our bodies.

And so hair lice in that regard are fascinating.

Head lice are living fossils.

They are the ultimate survival machines.

- Lice approximately appeared on Earth

somewhere in the region of 115 to 130 million years ago.

- This means that they predate

the great extinction event that killed off dinosaurs

and wiped out 75% of all species.

At London's natural history museum

Dr. Vincent Smith takes a special interest

in these blood sucking parasites.

- There are about 5,000 species of lice in total.

This one here is a human head louse.

This is a female.

It's highly adapted to living on humans.

So they have these thick sharp claws

and a groove under the louse where the hair sits

so that they can cling on.

- Lice must live on their host.

If they fall off, that's it, they're dead.

- Right at the front is the mouth

where tiny sharp tubes get out

and they find a blood vessel and they feed on the blood.

- Yet despite these advanced features

lice can't walk, crawl, or fly.

They live lonely lives

until we come together.

(children playing and laughing)

When our body parts meet

lice don't miss the opportunity to jump ship.

- One of the reasons why lice spread particularly quickly

in young children is because many

of the social barriers that we would normally have as adults

don't exist in young kids.

You'll see them touching, hugging each other all the time,

and that is a perfect medium for the transfer of lice.

- In a school room head lice

can pass over several heads within an hour.

- The head lice can be really difficult to get rid of.

Almost none of the traditional insecticides will work

and you have to use other means

usually physical means simply to get rid of lice.

- But lice are more than just an irritation.

They've changed us in fundamental ways.

(heavy breathing)

(triumphant horn music)

One of the striking things about the human body

is its hairlessness.

- Fur was an evolutionary breakthrough.

A warm hug on a cold day

that allowed mammals to live in conditions too hostile

for reptiles and birds.

And once hair evolved 120 million years ago

it was rarely lost.

Yet we ended up virtually hairless.

Why?

- Some people think that it's

it was actually to help lose our lousy infestations.

That there were fewer exoparasites,

lice, and fleas, and other things

because they can't really cling to a naked skin.

- A furry coat is a safe haven

for ticks, lice, fleas, and other blood suckers.

And they're not only annoying

but some of them can carry lethal diseases.

- Lice and fleas and their kin

they don't kill us in and of themselves

but because most exoparasites take our blood

they also have the capability of transmitting disease.

And so that those individuals who had less fur

were actually at a reduced risk of disease

from these exoparasites.

- Hairlessness was an attractive sign

of good health.

Just like the bright plumage of birds

is an advertisement for being free of parasites.

It was favored by sexual selection

and this ensured that the naked genes

were passed down to the next generation.

And ever since we've become obsessed with removing hair.

We spend billions annually on razor blades

and getting waxed,

but some parts of our body are hairy.

This puzzled Professor Robin Weiss

at University College London.

- Why do we have pubic hair?

My guess, and this is just hand waving,

is that pubic hair isn't just a remnant

of when we were furry,

but it's an active evolutionary selection

of a big bush of hair.

- And if this idea is right

then we wouldn't expect to find pubic hair

on our furry cousins.

Professor Weiss wanted to find out.

- Well that was a great excuse to go to the zoo

with two of my grandchildren

and while they were looking at the antics of the apes

I was looking at the ape's genital regions.

And sure enough they don't have pubic hair.

They have some fur, but if anything,

amongst apes and monkeys it's shorter and smoother

than on other parts of the body.

They're the very opposite of humans.

They have less hair around the genital region.

- So if our primate cousins don't have pubic hair

where does ours come from?

- Sexually immature humans, children don't have it,

but males and females do.

- Could pubic hair have evolved then

to indicate that mating could be fruitful?

The clue to this puzzle is those pesky parasites, lice.

(salsa music)

It was assumed the pubic lice

were a close relative of head lice

which makes sense if they both came from a time

when we were furry all over,

but on closer examination

the two couldn't be more different.

- The crabs or pubic lice have these great big claws

to clasp around coarse hairs.

- They couldn't live on our head

which means we got them and pubic hair

after we lost our fur.

- Closest known relative to the humam pubic louse

is the gorilla hair louse.

Gorilla's have coarse hair and those lice

are already adapted to live on coarse hair

like pubic hair should they get across to humans.

- And so it looks as though around eight million years ago

an ancestor of modern gorillas

and one of our ancestors came close enough to exchange lice.

- There must have been some close physical contact

for us to have acquired that louse.

- What happened in that moment

only the gorilla ancestor and our ancestor know.

I suspect it was a little bit tawdry.

- I mean the suggestion is it was sexual.

- One thing's for sure

one way or another we got crabs from them.

Since then, genital lice have traveled the world with us,

but now we're getting our revenge.

(upbeat salsa music)

In 1987 seven Brazilian women, the Padilha sisters,

opened the J. Sisters salon

to offer what they had done, the Brazilian wax.

The complete removal of hair from the pubic area.

- The first time I did it it was a little uncomfortable,

but I noticed right away a lot of changes.

I sweat less in the summer.

- In only a few years this form of waxing

has gone from the exotic to the everyday.

- It went like all over, people coming from television,

from all over.

They wanted to know what is this?

- It's the most successful innovation

in hairdressing since the permanent wave.

- I Get mine done about every five weeks

and I'm addicted to it.

- But this addiction to the Brazilian

is actually threatening pubic lice with extinction.

- You take away their habitat

and they can crawl on, but they can't hold on.

- I feel very proud of ourselves

that they might be extinct.

It's ugly.

It's very ugly.

- Imagine a whole suite of species like this

that were used to holding onto us

and then as our hair fell away

they lost their habitat.

- We evolved hairlessness

to rid ourselves of parasites.

Exposing our dark skin to the African sun,

but as we ventured to cooler climates

our skin became pale.

We owe these differences in our skin color

to our interaction with the bugs that live on us.

- These are very fundamental aspects

of what it is to be us

that are plausibly linked to these little organisms

that crawl around in our skin

and hang onto our fur.

(intense music)

- We are not alone.

Bugs have been our constant companions.

The hidden force behind your health,

your skin color, and even your behavior.

Whatever you are, you owe to them.

Microbes have been the making of us.

(dramatic music)

Life is an endless fight.

A battle for food and sex,

but often the winning strategy is a balance of power.

A truce between rivals.

The same happens inside our bodies

where trillions of organisms have evolved to share us.

(ants scratching)

There are worms in your bowel.

- You're nearly finished. - Colonies of bacteria

on your teeth.

Fungi thrive in your lungs

and viruses embed themselves in your DNA.

Collectively this menagerie of bugs

is called your microbiome

and it's as much apart of you

as any of your organs.

We are essentially an assembly

of a lot of different organisms, ourselves included.

- Microbes have helped us to evolve.

They've made us who we are.

- They were there right from the evolution of human beings

as hunter gatherers.

Even right back to the evolution of mammals.

(spraying)

- But in the blink of an eye

we've cut ourselves adrift from nature.

(toothbrush brushing)

- We've gone from a daily life in which we were exposed

to thousands and thousands of species

of many different kinds.

Where we ate food with dirt still on it.

Where we had worms

and then all of a sudden we move into these environments

where we've convinced ourselves

that all other species aside from our dogs

and our lovers and our kids are bad.

- Believing it makes us healthier

we do our best to scrub bugs off our bodies.

We've unleashed a war on germs

and now we are paying the price.

(water pouring)

- Modern medicine is about killing bad species.

We are really good at thinking

about medicine in that context.

You know, something bad makes us sick

we kill it, we get better,

but the idea that something good is missing

and that that makes us sick

we don't have much of a framework for that.

The medicine that would be required

to think about this in the right way

would need to think about the body as an ecosystem.

- In this revolution in medicine

it's the bugs that will save us.

This is a journey into the human body.

Your insides are a battle ground

and it's your health that's at stake.

(machine drilling)

Our tour begins at the mouth.

All is not well with the main entrance.

- Dental decay in this world now

in talking about all countries is

uh, plague proportions.

- Tooth decay now effects around 90%

of children worldwide and can lead to serious diseases.

It's an epidemic of the modern age.

Compared to us our ancestors had pearly whites

and they didn't even brush their teeth.

It's a mystery that fascinated DNA detective

Professor Alan Cooper.

He's been studying teeth throughout the ages.

- When you do look at the hunter gatherer populations

you see very little signs of dental caries,

the holes in your teeth.

They look in really good nick.

- But the closer we come to modern people

the worse the teeth become.

- As soon as you start moving from the hunter gatherer phase

into the farming phase the teeth look terrible.

You know, there's dental carries.

There's gum disease 'cause of the bacteria

around the base of the teeth.

Um, nasty pathologies.

- And the consequences

are far more profound than bad teeth.

If Cooper could discover what's gone wrong inside our mouths

it might help explain the rise

of some of our most serious diseases.

- We think oh well, we get a bit of bleeding.

Gums, we have to go to the dentist a bit, no big deal.

We got holes in our teeth.

What we don't realize is that the bacteria

are leaking down through those inflamed gums

into our blood system

and stimulating all sorts of immune responses

and these immune responses are now being linked increasingly

to a huge range of modern western diseases.

Cardiovascular disease, diabetes, hypertension,

premature birth, cancer.

The list goes on and on.

- In one way or another

the key to it all is bacteria.

(soft piano music)

There are more than a hundred million bacteria

in every drop of saliva.

An eco system of 700 hundred different species.

And there is no place they like better

than the wet surfaces of our teeth.

Here they form a layer or biofilm

that dentists call plaque.

- It happens every night when we're sleeping.

The plaque, the layer of bacteria

on our teeth gets calcified

and slowly builds up over time.

This is what the dentist is removing.

- We provide bacteria with a home

which is just as well because without them

we'd have no teeth.

The microbes in our mouth protect us from the food we eat.

- We have evolved in the presence of acids.

Most foods that we eat

most of our diet is essentially acidic.

At the same time the enamel

which makes up the outside surface of the tooth

is inorganic and will dissolve in acid.

So here we've got this conundrum

trying to work out well what's happening here?

How does a tooth stop itself from dissolving?

- The answer is biofilm,

a dense layer of bacteria that's stuck on our teeth.

As acid eats away at the enamel bacteria fills in the holes.

- The tooth starts to dissolve

then the raw products of this process

get caught into the biofilm and the right environment

get reused to heal the tooth.

- In a healthy mouth everything works in balance

and the good bacteria protects us from decay.

(spitting loudly)

(water running)

- These microscopic dentists have looked after our teeth

for much of our evolution.

So what's changed?

- We can only judge that

if we've got an idea about what it looked like before hand.

- But there was a problem.

There's no bacteria left alive

on the teeth of museum skulls.

- There seemed to be no way that we could actually get

a look at what a bacterial microbiome

would look like in the past

until we thought about those calcified plaque on the teeth.

- It was an ingenious solution

locked in the plaque of our ancestors

were the fossilized remains of vast numbers of bacteria

and compared to us there was a striking difference.

- Everything goes completely strange

when the industrial revolution comes in 1850

and suddenly you're getting large amounts of processed sugar

and flour become available.

And at that point the diversity

of the bacteria in the mouth just drops away

and huge amounts of these pathogenic bacteria

become very obvious in everybody we look at.

- A bunch of disease causing bacteria

has taken over our mouth.

They thrive on our modern diet of processed food

and that's changed the game.

- These organisms tend to make,

be little acid factories

producing acid onto the tooth's surface

which then starts to dissolve the enamel away

and lower the pH of the environment.

And they're able to withstand that low pH.

That harsh condition that other microbes in the mouth have.

- And the good bacteria that don't

like living in acid conditions

good bacteria that normally keep

the bad bacteria under control

just like in the gut

then these die off.

- Our changing diet

unleashed a war inside our mouth

and the bad guys are winning.

Acidity in our mouth is a problem,

but there's one place where we couldn't do without it,

our stomach.

- It's a filter that kills lots of pathogens.

We eat food full of microbes

and one of the reasons those don't just colonize

and take over our gut

is that we have this stomach with adaptations

for dealing with the microbes.

- In fact healthy humans can eat just about anything

because 99% of the bacteria in your food

are killed by the stomach acid.

It's certainly enough to dissolve nails

and you have these stories over the years

of people who try to kill themselves

by eating razor blades, or nails, et cetera,

and a few months later you look in this stomach

and you can only find a few old rusty fragments.

It's almost totally digested.

- The only bacteria that survives the acid bath

is the bug called the gastric demon,

Helicobacter pylori.

- Helicobacter is very very interesting.

It's somewhere in between a harmful one

and a harmless beneficial one.

(trumpet music)

- No one knows this bug

better than Australian Barry Marshall.

In 2005 he shared the Nobel Prize

with Robin Warren for discovering its power over us.

- The reason people didn't look for bacteria in the stomach

before the 1970's when Dr. Warren first saw them

uh, was that

they knew that bacteria could not live in acid.

It's too dangerous.

(sizzling)

- But we now know some bacteria

have learned to survive in extreme environments.

And the gastric demon is one of them.

- So the question is then,

how do bacteria survive in acid?

And the next discovery was that

the bacteria can make ammonia

and ammonia neutralizes acid.

(haunting music)

- Helicobacter has a nasty reputation.

It's called the gastric demon for a reason.

It causes stomach cancer and gastric ulcers.

(beeping)

Marshall and Warren were the first to show

that ulcers weren't triggered by stress

or spicy food as it was commonly thought

but by infection with Helicobacter.

- However we could never get over this issue

that lots of people had the bacteria and never got an ulcer

and so the skeptics could always say,

"You must be wrong because I had lots of people

"with Helicobacter and they never

"had a days illness in their life."

(calypso music)

- And even more puzzling

is that in the developing world

where the gastric demon is rampant

hardly anyone gets ulcers.

Somehow a dangerous bacteria for the rich

is harmless for the poor

and the difference between the two is another parasite,

worms.

- Helicobacter pylori causes ulcers

if you don't also have parasitic worms.

You can't just have a part of the ecosystem.

You need the whole ecosystem.

- It's all a question of balance.

The proportion of worms and bacteria

needs to be just right for a healthy body.

- But just to show how subtle all of this is

if you remove Helicobacter pylori

which is what we're doing nowadays with antibiotic

we get another problem.

- The eviction of Helicobacter

in the western world has contributed

to the rise of new diseases,

like asthma and allergies.

- So it's in this gray area.

Causes cancer or ulcers.

Possibly prevents asthma,

but the reason it prevents asthma

is possible more important than

all the terrible things it does.

(birds chirping)

- Helicobacter is an invader

that keeps our immune system busy

and if it's not present

we can overreact against harmless stuff like pollen or pets.

- If you could find the correct strain

which you could control

then I think it would resurrect Helicobacter

as a useful bacteria.

- If we could tame the gastric demon

it might become a live vaccine against allergies.

- So I think there are all kinds of possibilities.

I'm quite excited about it

and we are already testing Helicobacter products

in human volunteers at the University of Western Australia.

(water splashing)

(dog barking)

- Bacteria, fungi, and worms,

are invading us all the time.

In fact they come as a side order with every bit you take,

but some people can't get enough of these nasty parasites.

They want more.

(bouncy guitar music)

(water pouring)

(sizzling)

Our food contains more than we bargained for.

It's loaded with bacteria, fungi,

and sometimes the eggs of parasitic worms.

Richard Faulks loves his ham and eggs,

but this breakfast is being sacrificed

in the name of science.

Faulks built the world's first artificial stomach

and today he is out to discover

if worm eggs survive the gut's acid test.

- This is my breakfast

and I'm now going to add just a pinch

of intestinal parasite eggs

and mix it before putting it into the stomach.

(water pouring)

(bouncy guitar music)

- Ahead lies a hydrochloric acid bath

that will kill just about anything.

- Everything was normal.

(liquid pouring)

The whole thing is operating at 37 degrees centigrade

which is the same temperature as the body.

The first sample is now just being ejected.

This is the material which actually ends up going down

into the duodenum and into the intestine.

- But do the parasites survive the journey?

(intense orchestra music)

- Well as we expected

most of these parasite eggs seem to be viable.

- Worms are one of nature's great survivors.

They thrive in some of the planet's

most inhospitable environments

including your insides.

The ones in our gut look like aliens from a sci-fi movie

and incredibly they originally came

from the murky depths of the oceans.

They were able to come on land

by colonizing the guts of animals

including us.

They're after a rich food supply,

your blood.

Parasitic worms love us

and in turn we are beginning to love them back.

- If I had Crohn's disease, or ulcerative colitis,

or multiple sclerosis,

I would infect myself without hesitation.

- A colleague and I gave ourselves hookworms

and my colleague had 20 hookworms

and I only had six

and being a competitive person

I thought well I'm going to get more.

I gather you've got--

- Dr. John Croese and Alex Lucas

are hooked on worms.

- Worms are both bad and good.

In developed countries where we are well nourished

worms are potentially good.

- The medical use of worms

is now being put to the test.

Hugh Sheardon is suffering from celiac disease,

a nasty reaction to gluten

that causes severe diarrhea and pain.

He and Judy Noonan are part of a pioneering clinical trial.

- We are experimentally infecting

these people with hookworms

to see if the infection has a therapeutic benefit

on their Crohn's disease or celiac disease.

- These are diseases where

the immune system attacks the lining of the intestines

causing chronic inflammation.

So how can worms fix the problem?

- The last thing a worm wants to do

is have our immune system eject it.

They modulate the immune system

and send it in a direction

that just generally dampens inflammation

and that protects them.

Stops them from being attacked,

but the benefit of that is that inflammation

in general is suppressed.

- As it turns out it's the worms spit

that carries the magic ingredient.

- As a hookworm attaches it releases all sorts

of salivary proteins

and some of those have immunized suppressive properties.

(stove clicking)

- With worms on board

Hugh's immune system is turned down

and should stop overreacting to gluten in pasta.

- The aim is to use hookworm

to change the immune response to gluten.

- For people with celiac disease

any amount of pasta can be dangerous.

Six weeks with worms and Hugh's reached a milestone.

It's a tiny morsel,

but previously even this would have made him sick.

- When we reintroduce gluten to celiacs

who have hook work infection

that their response will be muted

and now start to tolerate low doses of gluten.

- For Hugh Sheardon

the experiment was a success.

At the end of the trial he could eat a full bowl of pasta.

- Live worm therapy is a good proof of concept,

but I don't think it will ever become

a scalable, widely used method of treating inflammation.

However if we can identify and harness

the actual molecules that are responsible

we can then turn those into a much more

conventional type of drug.

- But desperate patients aren't willing to wait.

An approved drug will take many years to develop.

- Nice to see you.

Come on. - Nice to see you too.

- Come on please take a seat.

Welcome.

- So the seriously ill

are signing up for treatments in the hookworm underground.

- Originally I was diagnosed with ulcerative colitis.

- Yes.

- And because those medications weren't working for me

they switched it to irritable bowel syndrome.

- Can I have your arm please.

Just pull here.

- People should be allowed to pursue alternative therapies.

Especially when the other possibility seems not so great.

On the other hand if it's not proven to work

then you don't know it works.

Then you're basically just buying into a dream.

(calm guitar music)

- Valesquez-Manoff is a science writer,

but his interest in alternative therapy is very personal.

- My whole life I've had asthma.

I've had food allergies

and I've had, starting at age 11,

I have an auto immune disorder called alopecia areata

which means my immune system turned on my hair follicles

basically shutting them down.

- After researching his health problems

Moises made arrangements to be inoculated

with the so called American murderer,

Necator americanus.

It's a parasite that has plagued humanity for centuries.

Moises traveled to a private clinic in Mexico

just across the border from the US

where using worms for medical purposes remains illegal.

- Of course I was a little bit nervous

because I'm doing something that frankly

most people will tell you is stupid and it probably is.

I wasn't that scared though 'cause I knew

that scientists around the world had self infected

'cause the reality is you can't study these things

unless you keep a colony alive somewhere.

They only live in humans

so they just have them in their own guts

and then when they need them they cultivate them.

(slow guitar music)

- One of those who cultivated his own worms

is the owner of the Mexican clinic, Garin Aglietti.

- Parasitology has a story tradition of self experimentation

and so what we're trying to do

is remove the barriers to access for this

because I don't want everyone to have to do what I did

was basically when I became ill

and was looking for access,

you go to the professional scientists

and they can't help you.

They're bound by institutional review boards

and professional standards

and appropriate treatment corridors.

- Garin Aglietti's life was plagued

by chronic immune disorders.

Conventional medicine offered no help

so in desperation he turned to worms,

but first he had to find them.

(plane engine)

He traveled to Peru

where the American murderer was common.

Collecting worms is not for the faint hearted.

The process requires doing something

called a latrine survey.

- A latrine survey basically means

just taking samples of soil and feces

and collecting it and cataloging it.

It's just about as much fun as it sounds.

I think it was the Ortiz family

was the one that turned out to be the hottest one

and the thing that I wasn't prepared for

is that I had to beat the chickens

'cause the chickens were going down to eat it

and if they got there first

then everything was gonna be gone

so I had to go me run around trying to get to the chickens.

- After harvesting his medicine

Aglietti infested himself with seven microscopic larvae

and the offspring of those worms

are now used by doctors to treat patients in his clinic.

Once inside us the hookworms face a perilous journey.

Yet they are well adapted to the challenges

our body throws at them.

- If you apply 50 live hookworm larvae to the skin

you can be assured that those 50 larvae

will get into the gut.

- The larvae hitchhike aboard blood vessels

and flow through the bloodstream like rafters on a river.

They will pass through the heart before reaching the lung.

- They're going to irritate the lung a little bit.

Lungs are going to produce a little bit more phlegm.

The phlegm goes all the way to your throat

and you swallow it, okay?

So they got into the stomach which is full of acid,

but the phlegm is actually protecting the worm

so they don't get burned by the acid.

That's nature.

- Once the worms reach the intestines

they announce themselves to the immune system

by taking their first bloody meal and that sucks.

- The side effect phase was a bit of an experience

and had I not been so committed

to never doing a latrine survey again

I don't know if I would have gotten through it.

- Those side effects include cramps,

nausea, and diarrhea,

the body's natural response to shake

itself free of the parasites.

- They are painful to have.

Those symptoms sort of waned over time

and I also saw some benefits.

Like, about a few, let's say four months

after I took the parasites was hay fever season.

For the first half of hay fever season

I completely lost my allergies.

It was amazing.

I never lost my food allergies.

I still had those.

(intense music)

- The worms can manipulate our immune system

in a way that modern medicine is yet to match.

- So I think just 'cause you can kill all the worms

doesn't mean it's necessarily a good idea

to kill all the worms.

- It does work for some people.

It also doesn't work.

I interviewed some people who got worse.

So actually would not recommend it.

On the other hand it doesn't change

any of the evolutionary argument that we're making here

and that is that our immune system

comes to expect stimuli like these

and we need to replace it somehow.

- These therapies remain unproven,

but one way or another worms are forcing us

to reconsider our approach to treating western diseases,

but they are just one of our microscopic tenants.

There are a hundred trillion more

in the most unloved place of our body,

the colon.

Gastroenterologist, Thomas Borody,

discovered the power of poo

and he's saving lives with it.

- Amongst the last unexplored regions on Earth

are caves.

They hold species that are unknown to science.

Yet they are no match for the dark corridors of your bowel.

Here there are more bacteria on

just a single square centimeter

than all the humans who've ever lived.

- There's ten times more living cells in the stool

than there is in our body.

So in effect we are 10% human and 90% poo.

- The microbes in the gut

aren't just along for the ride.

They are essential for the development of the brain,

the immune system, our overall health,

and even our mood, and body shape.

- These bacteria depending on the composition

can control weight gain, weight loss,

and develop in to have insulin resistance.

So there's a large sort of vast mechanisms

that are inside our bowel flora that are responsible

which are just emerging.

- Yet we are damaging our gut flora

even before understanding it.

- We know that when you take too many antibiotics

that one of the things that happens

is it puts you at extreme risk for pathogens.

- It kills off all of the friendlies

and so then bad bacterium takes over and the patient dies.

- So instead of prescribing antibiotics

to kill the bacteria

Gastroenterologist Thomas Borody does the opposite.

He adds bacteria.

Trillions of them.

- Start going forward.

- Professor Borody is the pioneer

of fecal transplants.

To treat digestive diseases he replaces infected gut flora

with healthy poo.

- Well it's still disgusting to me as well.

I'm just like anybody else,

but you see the potential because in its healthy form

with full diversity and lots of bacteria

is able to enter another person's bowel

and kill off bugs that cause disease.

- Despite all we've learned

of poo being smelly waste

for Borody it's medicine.

Our colon is a factory producing bacteria

that thrives on foods we can't digest.

- The bacteria eat them.

When bacteria eat them they multiply

so we have to let them out the other end

and that's why we defecate.

- And defecate we do.

An average person will produce

more than four tons of feces in their lifetime.

(upbeat orchestra music)

Borody has opened a new frontier in medicine.

Every morning healthy donors arrive at his clinic

with a fresh supply to cater for people

with gastrointestinal diseases.

Kati Angelidis suffers from debilitating bowel problems.

- I was used to that blank stare

you know when I'd ask them what was wrong with me.

How can you help me?

When you have got issues you've been

to hell and back with your sympoms

so you will do anything to, you know,

get some kind of improvement.

- Professor Borody will perform

seven to ten treatments like this everyday

and many more would come if they could afford it.

- The cost is prohibitive to get it done

in a clinic for them

so they're doing it at home

plenty of them.

A lot of parents doing it for kids, you know,

with Crohn's disease or whatever

and they're desperate, they're helpless.

You know, they'll do anything.

So yeah it's a bit underground, isn't it?

But yeah it's happening.

- People are still trying to work out

the best way of doing it.

I mean do you put it in that way

or that way

(laughing)

or like radio controlled capsule

you just swallow and open up

with some sort of radio controlled signal

and then the capsule carries on?

You know, the technologies are being developed.

There are going to be some very clever ways of doing this.

- Tending our microbial garden

also helps with diseases that having nothing to do

with digestive problems.

20 years ago William Kostopoulos

had his wisdom teeth removed.

It didn't go well.

- My body went into trauma.

They thought actually I had a stroke.

They sent me to a neurologist

and then they gave me an MRI scan

and um, after the MRI scan

they told me that I had a mass multiple sclerosis.

- It was devastating news.

- There was times you feel like just killing yourself.

Your life is revolving around medication,

and doctors,

and MRI scans,

and treatments,

and hospital.

- Realizing the disease couldn't be beaten...

- Good to see you.

- He went to see Professor Borody.

- We spoke about some sort of transplant.

A poo transplant as he puts it

and um, I was open to anything at that stage

because I was suffering through

three and a half years, four years,

- William had the transplant

and incredibly he has completely recovered.

- Things are fantastic.

Things couldn't be better.

I mean I'm 49 now.

I'm heading to 50 so, you know,

(scoffs)

but I don't feel 50.

I still feel like I'm 20.

(speaking lowly into recorder)

- That was a fortuitous finding

and we had three such patients

and we went on treating their MS

they did not come to us for that purpose.

We were treating the bowel disturbance.

- For now these are anecdotal results.

Yet the treatment designed for digestive diseases

seems to be having even more intriguing side effects.

- We have had at least two patients

in whom profound depression was able to be reversed

and I didn't notice that.

The patient said to me after he had

a transplant done for a different cause

he said, "My depression is gone."

I said to him, "What do you mean your depression's gone?

"How can that be?"

He said, "Well I've had depression for 25 years doc.

"I know when the depression is gone."

So I wasn't gonna argue with him.

- Gut microbes influence our body and mind

in fundamental yet inexplicable ways.

There's so many changes that we've seen patients

that are difficult to believe when we change patients flora.

Why is this so?

There are so many questions to be answered.

- If we can explain the links

between our microbial ecosystem and chronic disease

it will revolutionize medicine.

As the first step microbiome explorers

are signing up volunteers to donate a dollop of poop.

(toilet flushing)

- They're currently sequencing lots of shit in the US

and I heard that's just been expanded worldwide now.

So when we do the survey, a very wide survey,

that's important too that we can see

across the whole human population what the variety is

and we can see how that relates to people's health

or lack of health.

- These initial surveys have

already revealed thousands of bacteria we never knew before.

Our inner continent is terra incognita.

- Every person is colonized with these species

that have an enormous effect on how they live,

their health and well being for their entire life

and in many cases we can't give them names.

- But we've already discovered bugs

that make us fat or thin.

A group of bacteria called Firnicutes

helps the absorption of fat by the body.

Depending on which ones you have

you may have absolutely complete digestion of your food

and I suppose the theory is that

then you're one of these people

that has a small about of food and puts on a kilo everyday.

Whereas other people might eat the same amount

and not put on any weight.

- Having these fat bugs on board

is the equivalent of eating a slice of cake everyday.

- Historically if you had a group of microbes

that gave you lots of energy from your food

it would be enormously beneficial

because you could go longer without food and survive.

You would need less food everyday

but now we're all fat.

- Luckily there is a bug

that helps keep you thin.

Accermansia may one day lead to a treatment for obesity.

- I think we might have yogurts in the future

or something like this which will give you

the sort of skinny yogurt together with bugs

and I'll be eating a lot of those.

- Ultimately our health will be determined

by the diversity of bugs in our gut

and the balance between the beneficial and the bad

and that varies from one culture to the next.

(children laughing)

- If you look at the gut flora

or for instance people living in a little African village

and compare that with the gut flora

of people living in Italy they are so different.

- People in developing countries

have a richer and more balanced gut flora

than those in the west.

And that helps explain why the affluent

are more prone to modern diseases.

- Now one reason is clearly diet.

We eat crap.

(meat sizzling)

- When you eat you don't only feed yourself.

You're also feeding your mirobes,

but in the west we are nourishing

the bugs that make us sick.

These bad bugs release toxins that trigger

a violent response from our immune system

and that causes inflammation.

- What happens when you eat junk food

is that you become immediately inflamed.

Your microbes actually inflame you

in the presence of junk food.

- And that inflammation runs

through your body like wildfire.

- And the higher that low level

of background inflammation is

the more susceptible you are to all sorts of disorders.

- These are diseases

of an out of balance immune system

ranging from inflammatory bowel syndrome

to multiple sclerosis, Crohn's disease,

obesity, and allergies.

- Inflammation is at the sort of root of all of them.

- Just as our mouth microbiome

has been disturbed by eating too much carbohydrate

antibiotics and bad diet have turned the bacteria in our gut

from friend into foe.

- We've moved in incredibly few generations

from lives as hunter gatherers,

to lives as agriculturalists,

to lives in places like Hong Kong

where people live in 60 story buildings

and they're totally disconnected

from any of the wildlife around them.

This whole web, this whole ecosystem, or biome,

it's changing and so what we need moving forward

is to figure out how do we garden

the beneficial parts of this web?

- This idea of reconnecting us

to what we are missing from the environment

is the life's work of British scientist,

Professor John Stanford.

He's found something in an African mud puddle

that some are calling the wonder bug.

Cynthia Stanford had a rare condition

called Raynaud's disease.

Her fingers turn numb and white when exposed to cold.

- Jobs in the kitchen were a problem

washing up or peeling carrots, peeling potatoes.

My fingers used to go into total white out and be unusable.

- By coincidence her husband

Professor John Stanford was testing

a new vaccine for leprosy.

It contained a bacteria he'd isolated

in a mud puddle in Uganda.

It was called M. vaccae.

- Since we were the ones that were had developed it

we wanted to try it on ourselves first

before we gave it to anybody else.

- John and I had a dose each

and I realized that my Raynaud's disease

that I'd had since I was a small girl had gone away

and so after that we lined up

all the rest of the family who also had Raynaud's disease,

but they also had other things.

- The vaccine appeared to be helpful

in dealing with the other diseases that run in the family

including even cancer.

- My mother had cancer at the same time

as her Raynaud's disease

which disappeared including spinal secondaries.

- She had her M. vaccae injection

and then a month or so afterward

when she went for radiological assessment

before having the radiation

they say, "Well they've disappeared."

- These results were entirely anecdotal,

but the bacterial treatment began

to have surprising results elsewhere too.

- I asked an Indian doctor who was doing leprosy work

if he would look out for any other indications

that it seemed to be helpful with.

- The first one that he noticed

which was really quite important

was a patient with leprosy and cirrhosis.

Remarkably the cirrhosis got better.

He was so pleased that when we were out there visiting

he brought us um, a small goat to give us in exchange

for the good that we've done to him.

- Stanford's discovery

is now being tested in clinical trials

and one of the most promising is for depression.

- Drugs that are commonly used to treat depression

have anti inflammatory effects

and so one of the ways that they

may be improving the health of depressed patients

is by suppressing the inflammation

which is exactly what microbacteria M. vaccae does.

(flute and bell music)

- Inflammatory diseases

are problems of the immune system,

but how could something so complex

be controlled by a bacterium from Africa?

- Humans co-evolved with these bacteria

throughout evolution and so it's thought that

until about the last 50 years or so

we would have consumed milligram quantities

of these bacteria.

- So the immune system began to rely

on the presence of these things

to turn on the police force if you'd like

of the immune system.

(intense music)

- Without microbes like M. vaccae

the immune system becomes overactive

and causes constant inflammation.

- You spend all this time thinking

about our immune system as this machine

that repelled microbes.

That just zapped them left and right

like one of those fly zappers

and it turns out that the immune system

that we thought had evolved to kill microbes

is actually controlled by microbes.

- Our modern lives however

are isolating us from the very thing

we need to stay healthy.

- Now of course we don't consume these bacteria

because we have sterilized water and sterilized food

and it's thought that the lack of these bacteria

is contributing to an increase in disease.

Specifically diseases that are related to inflammations.

- The evidence now strongly suggests

that the rise in these diseases

is a result of our isolation from

the microbes we've evolved with.

Soon we may be able to treat immune disorders

by putting the bugs back into our bodies,

but the potential of bacterial treatments goes even further.

Australian scientists are now injecting bacteria

into mosquitoes to prevent us from getting sick.

(crickets chirping)

Mozzies are annoying at the best of times.

(mosquito buzzing)

They've developed elaborate weapons

to get the food they need to survive,

our blood.

- Mosquitoes need blood for protein to make eggs.

Only the female mosquito feeds on blood

and without it she really won't develop enough eggs to lie.

- But these syringes don't only draw blood.

They also often inject us with potentially lethal parasites

causing serious infections like dengue fever.

- Dengue is actually cause by four quite different viruses

and each of them has quite a different effect on the host.

- So you literally have to have

four vaccines rolled into one.

- But scientists at Monash University

have discovered an elegant way to combat the disease.

Instead of vaccinating humans

they are vaccinating the mosquitoes.

These mosquito eggs are being injected

with a powerful bacteria called Wolbachia.

(enchanting music)

Professor Scott O'Neill has spent much of his career

studying this intriguing bacteria.

- I got introduces to it at a very early age

and it hooked me enough.

Been studying it my whole life.

And so one of the most amazing things about wolbachia

is just how common it is.

If you were to look in a bush land environment like this

and look at the insects within it

around 70% of those insects

would all carry wolbachia natrually.

And when you think on the planet

that there are to to five million

different species of insect that's a huge number

that naturally carry wolbachia.

- Just as gut bacteria can be good for us

wolbachia is beneficial to insects.

Protecting them against invading parasites.

- By having wolbachia within the body of the insect

it's acting like a probiotic for the insect if you'd like.

It's making the insect healthier

and makes it able to fend off some of these other pathogens

like dengue viruses.

- But there's a catch.

Mozzies that spread diseases like dengue

don't have wolbachia.

So the challenge was to find a way to infect them.

- In fact, you know, we spent years and years

trying to do that experiment.

Had many poor students fail in that endeavor

until finally we were able to succeed about four years ago.

(suspenseful music)

- These mosquitoes host wolbachia.

They are so precious that volunteers

will gladly sacrifice their ankles to feed them.

- We're rearing thousands, occasionally tens of thousands,

hundreds of thousands of mosquitoes and releasing them.

Not killing them.

- There have been outbreaks of dengue

in Australia's tropical north in recent years.

So to test their theory researchers

have been releasing the vaccinated mosquitoes in Cairns.

Once released wolbachia spreads quickly.

Every week they monitor how many

of the wild mosquitoes now have the bacteria

and the results are paying off.

- The releases that we did in 2011

are close to 100% infected with wolbachia.

- Wherever the mosquitoes

have been released dengue has been stopped in its tracks.

Following the success in Cairns

new trials have begun all over the world.

But even super bacteria like wolbachia have enemies.

Like all living things it's prey

for the ultimate parasite, viruses.

They are all around us.

In the air, in the soil, in the oceans,

and right now three trillion are inside you.

- Most of them are probably doing us no harm at all,

but a few of them are deadly, cause deadly diseases.

- From flu, to AIDS, to smallpox,

viruses have killed untold millions of people,

but some viruses, the retroviruses,

have an even more extraordinary power.

They have found a way into the very core of us, our DNA.

- On occasion the virus will infect cells

of what we call the germ line.

Those are the cells that are destined

to become eggs in females and sperm in males

and if they infect those cells and get into the chromosomes

then these retroviruses get a free ride

to the next generation.

- Robin Weiss was the first to prove

that viruses not only cause disease

they can become genes.

- It was an eureka moment to realize

that something that we think of as an infectious agent

as a virus going form one person to another

can be part of the normal inheritance.

- This was a mind blowing discovery.

By transforming into genes retroviruses

can replicate for millions of years.

They are the ultimate survivors.

- Their reason for living is to replicate themselves

so if you can embed yourself into another host

that's going to replicate your genome for you

you've probably reached nirvana.

- These viral invasions of DNA are rare events

occurring perhaps once in a million years.

Yet amazingly one is unfolding right now

in front of our eyes.

Veterinarian John Hanger noticed that something unusual

was killing the Australian icon,

the koala.

- It seemed almost inevitable

if they rang me up and said, "Oh we've got a sick koala,"

nine times out of ten it was a koala that was sick

with leukemia or lymphoma.

It was so common.

- When he investigated

Hanger discovered a retrovirus in the cancerous tissues.

- Every single koala that we looked at

and every single tissue that we isolated

some DNA from and tested

they were all positive for the retrovirus.

- It's the first time we see it.

On the other hand it's an example

of what we know has been happening

during evolution in any case.

(slow guitar music)

- We are the survivors of viral invasions

like the one that is waging war on koalas.

Human DNA is littered with the fossil remains

of these ancient battles.

- It's amazing really

about 8% of our DNA sequences

in our human DNA

is derived from retroviruses.

We are chock a block with fossil retroviruses.

- Until recently these genes

were considered insignificant, nothing more than junk,

but we now understand that these genetic fossils

have actually played a key role in evolution.

In fact without them we couldn't be born.

The same trick a virus uses to infect cells

now allows a mother and fetus to fuse together

through the placenta.

- This makes a very good efficient barrier

between the mother and the fetus

that is protective but allows nutrients

and oxygen to get across.

Thanks to a protein that was once millions of years ago

a protein used by the virus to infect cells.

- We shouldn't think of them

as a scary part of our machinery.

They're an absolutely essential component of what we are.

- An ancient retrovirus now intimately bonds

with every person on Earth

and it's just one of the trillions

of organisms that call us home.

Microbes define our life

and even our evolution.

- Would your personality be different

without all your microbes?

I think probably.

Would what you get from your food be different?

Certainly.

Would you differ in other ways we haven't yet thought about?

Almost assuredly.

And so our existence is part of this complexity of life.

(intense music)

(baby crying)

- We are not alone.

From the moment we are born until we die

we live in a delicately balanced relationship

with our private wildlife.

We are more than human.

Together we have become superhuman.