- [Jim] Welcome to a new and very strange
world of nature.
It's been taken over by the weird subatomic particles
of quantum physics.
As a physicist I've spent my working life studying
how these particles behave in the laboratory.
But now I'm heading out into the natural world.
I'm on a mission to prove that quantum physics can solve
the greatest mysteries in biology.
This is a real adventure for me.
I'm very much out of my comfort zone
trying to apply the very careful ideas
I'm familiar with in a physics laboratory
to the messy world of living things.
I believe that quantum physics could hold
many of life's secrets.
That deep in the cells of animals
particles glide through walls like ghosts.
That when plants capture sunlight,
their cells are invaded by shimmering waves
that could be everywhere at the same time.
And that even our human senses are tuning in
to strange quantum vibrations.
In the fantastic world of quantum biology,
life is a game of chance, played by quantum rules.
This is what I hope to convince you of,
to show you that quantum mechanics is essential
in explaining many of the important processes in life.
And potentially that quantum mechanics may even
underpin the very existence of life itself.
My quest begins with one of the
most majestic sites in nature, migration.
Every winter barnacled geese arrive right on cue
at the same Scottish river.
The end of an epic 2,000 mile voyage from
spalguard high above the arctic circle.
Of course many bids head south for winter,
then back home for summer.
But for decades, exactly how birds navigated
with such accuracy was one of the greatest mysteries
in biology.
So the most recent discovery has caused a sensation.
In the past few years, one species of bird has helped
create a scientific revolution.
I was one of many physicists who was shocked to discover
that it navigates using one of the strangest tricks
in the whole of science.
It utilizes a quirk of quantum mechanics,
one that bamboozled even the greatest of physicists
from Richard Feynman to Albert Einstein himself.
So you might be surprised to discover the identity
of this mysterious creature.
Say hello to the quantum robin.
This is the European robin.
Every year she migrates from northern Europe
to the tip of Spain and back.
In this laboratory in the woods, biologist Henrik Mouritsen
is trying to solve the mystery of how she does it.
But he's found himself in my world,
the strange world of quantum mechanics.
Quantum mechanics describes the very weird
behavior of subatomic particles.
Down in this realm of the very small,
we have to abandon common sense and intuition.
Instead, this is a world where objects can spread out
like waves.
Quantum particles can be in many places at once
and send each other mysterious communications.
- I set out to find out how the bird finds its way,
it just turned out that the data more and more pointed
towards this as the only explanation that could bring
all the different results together.
- [Jim] Henrik's investigating a long-standing theory,
that robins navigate by the earth's magnetic field.
His laboratory is an ingenious magnetic birdcage,
and these plastic cones lined with scratch sensitive paper
provide the key measurements.
Henrik's artificial magnetic field is like the earths,
except that he can point it in any direction he likes.
Inside their cones, the robins always respond to the field,
leaving scratches in a single direction.
The big mystery is how.
The earth's magnetic field is incredibly weak,
far too weak for any living creature to detect,
but Henrik has found an intriguing clue
by giving the quantum robin a mask.
- We have a little leather hood similar to what you put
on a falcon.
But just for a robin.
And then you have a hole in front of one eye
or a hole in front of the other eye.
What we can see is that if you cover up the right eye,
you turn off the magnetic compass processing
in the left part of the brain.
If you cover up this eye, you turn the compass off
in this part of the brain.
- The robin's magnetic compass seems to be in her eyes.
I can show you what's going on using my own eye.
Now we use our eyes for vision, but we also have a second
light detecting mechanism.
If I shine this torch into my eye, you can see that my pupil
closes down.
It's basically a defense mechanism to protect my eyes.
My eye is responding to particles of light or photons.
The energy provided by the photons is clearly enough
to activate chemical reactions.
After all, that's what controls my eye muscles.
Lights must be causing similar chemical reactions
in the robin's eyes.
In fact, it's the power supply for a unique form
of magnetic compass inside her cells,
in the weird world of subatomic particles,
a place where only quantum physics can explain
what's going on.
To see why, imagine the chemical reactions
in the robin's eye taking place in mountains
and valleys of energy.
To get a reaction to start, you have to push molecules
to the top of the mountain.
Thanks to Henrik's experiments, we now know that light does
most of the hard work.
But when it reaches the very peak, the molecule becomes
incredibly sensitive to the slightest touch.
The key point here is that the robin's chemical compass
is now balanced on an energy peak between two valleys.
Going one way produces one set of chemical products,
the other a different set.
Now even a tiny change in the earth's magnetic field
can tip the molecule over the top.
But the way this happens defies common sense.
The final piece of the puzzle depends on one of the
truly mind-boggling ideas in physics,
but don't worry if you find it hard to understand.
Even Albert Einstein called it "spooky."
The idea is called quantum entanglement.
It involves particles that seem to communicate
faster than the speed of light.
In 1935 Einstein published a famous paper
arguing that it was impossible,
but Einstein was wrong.
In recent years extremely delicate experiments have shown
that subatomic particles really are entangled.
It means they can subtly and instantaneously influence
each other across space.
And now it seems the same thing is going on
inside the robin's eye.
When a photon enters the robin's eye,
it creates what's called an entangled pair of electrons.
Here's how it works.
Each electron has two possible states.
For simplicity I'm choosing to call them red and green.
Now here's the weird thing, until I measure it,
it's neither one nor the other,
but both at the same time.
Think of the electrons like spinning discs.
They're simultaneously red and green,
but by firing a dart I can force the first electron
to be one or the other.
So far it's just a game of chance.
I don't know what I'll get until I try it.
So I know my first electron is red.
Suppose I now measure the second electron.
You'd think I have a 50-50 chance of getting red or green,
after all that's what you'd expect in the normal
everyday world, but you'd be wrong.
In quantum entanglement, electrons are mysteriously linked.
For example, if I get red on the first, I always get red
on the second.
It's not a game of chance anymore.
It's as if the first electron is telling the second
what to do.
That's why Einstein called it spooky.
The electrons seem to know that they should both
have the same color, no matter how far apart they are.
The really important part, is that two electrons
needn't be the same color.
They can be entangled in a different way,
so that if the first electron is red,
the second one is always green.
It seems that this mysterious connection is the ultimate
secret of the quantum robin's compass,
because the direction of the earth's magnetic field
can influence the outcome.
Near the equator they may be more likely to be red-red.
But near the pole they may be more likely to be red-green.
And that's the vital factor that finally tips the balance
of the robin's chemical compass.
Tiny variations in the earth's magnetic field
change the way electrons in the robin's eye are entangled,
and that's just enough to trigger her compass.
Now finally we can see how something as weak
as the earth's magnetic field can tip that balance
one way or the other.
If the message changes, the chemical reaction
tips a different way
changing the robin's compass reading.
- Suddenly it looks like it's a fundamentally quantum
mechanical phenomenon in birds,
it would be one of the first in biology.
- Biologists better get used to the weirdness of physics.
The robin is navigating by spooky quantum entanglement.
To see subtle quantum effects even in a controlled
sterile environment of a physics lab is really difficult.
And yet here's the robin doing it with ease.
These experiments are real and verifiable
and yet even though I'm seeing them with my own eyes,
I still find it hard to believe.
(upbeat country instrumental)
Bird navigation has brought physics and nature together
as the science of quantum biology.
There's a whole new world to explore.
But it's pioneers have found that it doesn't
just effect birds.
It effects every single one of us.
Because the latest experiments say you're doing
quantum physics right now.
And believe it or not, you're doing it with your nose.
Hello Gem, hello little girl.
Our sense of smell is remarkable
and quite different from our other senses
of sight and hearing.
Among the thousands of scents that we can recognize
many of them may well trigger very powerful memories
and emotions.
It's as though our sense of smell is wired directly
to our inner consciousness.
It's also different in another way.
The other senses of sight and hearing rely on us
detecting waves, light and sound,
but our sense of smell involves detecting particles,
chemical molecules.
Recently scientists have begun to realize that when it comes
to our sense of smell something very mysterious is going on.
For decades, biologists thought they knew exactly
how our noses sniffed out different chemicals.
But physicists like Jenny Brooks think there could be
a new ingredient in the mix,
and it smells like quantum mechanics.
- A lot of people think of the sense of smell and the
science of olfaction as being a problem that has been solved
and we know all about it.
And we do know a lot about it, we know about the ingredients
we know about the equipment that we use to smell,
but I would argue that there's a little bit more
for us to understand.
- [Jim] To understand more, I need someone to help me
with a smell test.
And Gem is going to sniff him out.
Every human being gives off a cocktail of chemicals.
Gem's nose could detect a single gram of it
dissolved over an entire city.
So she has no trouble finding the man I'm looking for.
Meet Colin, the gardener, a man who's used
to smelling the flowers.
- All right then Colin, I'm going to put your sniffing
skills to the test.
I've got a selection of chemicals here,
and I want you to tell me what they remind you of.
I'll start you off easily.
- Oh, that's like a minty vapor rub, menthol.
- Yep.
- It's that essence.
- All right, here's the next one.
You should be able to recognize this one.
- That's baking with my daughter, icing sugar.
- Vanilla, yeah.
When our noses detect a chemical, they fire a nerve signal
to our brains.
But different chemicals create different sensations.
The standard explanation for this has to do with the
shape of the molecules.
The conventional theory that goes back to the 1950s
says that the scent molecule has a particle shape
that allows it to fit in to the receptor molecules
in our nose.
If it has the right shape, it's like a hand in a glove
or a key in a lock.
In fact it's called the lock and key mechanism.
With the wrong shape it won't fit into the receptor,
but with the right shape, it fits into the receptor,
triggering that unique smell sensation.
Different receptors are wired to different parts
of our brains.
So when a menthol molecule locks into its specific receptor
it triggers that minty fresh sensation.
But the lock and key theory has always had a problem.
And Colin's next test will show you why.
- Ok, how about this one, a quite strong smell.
What does it remind you of, what memory does it conjure up?
- I think Christmas.
Christmas cake.
- [Jim] Marzipan.
- Yeah, that's it.
- Colin identified the smell of marzipan, or almonds.
In fact, it's due to a scent molecule called benzeldihyde.
What I didn't give him to smell
was this other chemical, cyanide.
Both benzeldihyde and cyanide have the same smell,
they both smell of almonds,
but these molecules are both very different shapes,
so the lock and key mechanism, as the explanation of
how we smell can't be the whole story.
So why would two molecules with different shapes
smell the same?
Quantum biology has a head-spinning explanation.
It says our noses aren't smelling chemical molecules,
they're listening to them.
It's not just the shape of a scent molecule that matters.
Let's take a closer look at this model
of a cyanide molecule.
The white ball here is a hydrogen atom and the gray sticks
are the bonds that hold it together with the carbon
and nitrogen.
But the reality isn't as simple as that.
I can give you a better sense of what's going on
if we look at this larger white ball.
You see atoms don't just sit still.
The bonds that hold them together are like
vibrating strings and that gives us a whole new way
of thinking about smell.
The bizarre new quantum theory of smell is all about
vibrating bonds.
Chemical molecules are playing music for our noses.
Imagine a receptor molecule in my nose is like my guitar.
Before it can make a sound, a scent molecule has to enter
my nose, and when that scent molecule is in place,
it's chemical bonds provide the strings,
and it's ready to be played.
The receptor molecules contain quantum particles, electrons.
As they leap from one atom to another, they vibrate
the bonds of the scent molecule, like my fingers
plucking a guitar string.
What's remarkable about this theory is that it tells us
our sense of smell is about the vibrations of molecules
or wave-like behavior, and not so much about the shape
of a particular scent molecule.
Our sense of smell may be much more like
our sense of hearing.
A particular molecule, say that of grass will vibrate
at a particular frequency.
But a different molecule, say that of mint,
will vibrate at a different frequency.
(plucked guitar strings)
This would explain why cyanide smells like almonds.
The two molecules have different shapes
but their chemical bonds just happen to vibrate
at the same frequency.
- The quantum vibration is almost literally like a particle
of sound, so I would say the process of smell could be
exactly like an acoustic resonance event.
It could be very analogous to hearing and seeing actually.
- [Jim] But can we really be listening with our noses?
A bizarre theory needs a bizarre experiment to test it.
Here's how it works.
Scientists used a molecule that smells fruity,
like orange blossom.
But if the theory is right, than I should be able
to change it's smell by changing it's vibrations.
The molecule contains lots of hydrogen atoms like this
bonded to carbon atoms.
But what if I were to replace all these atoms with a
different form of hydrogen called deuterium.
Now it won't change the shape of the molecule,
but it will change the way it vibrates, here's why.
Deuterium is twice as heavy as normal hydrogen
and so it vibrates more slowly.
Different vibrations mean different smells,
so if I were to make a new form of this chemical,
all packed with deuterium atoms instead of normal
hydrogen, it should smell different.
Quantum biologists found a unique way to carry out
this experiment.
A smell comparison using the real experts in fruity aromas.
Fruit flies.
First the flies were trained to avoid the modified version
of the fruity molecules.
To be honest I haven't got a clue about how you go about
training a fruit fly, but apparently you can.
In the laboratory, the flies had to pass through
a kind of a maze.
They were then given a choice.
Go right for the nice fruity smell
or left for the nasty modified version.
(flies buzzing and guitar)
They could definitely smell the difference.
They always preferred the original and turned right.
The fruit fly experiment gives hard evidence that
quantum smell theory really works.
But ultimately it works in harmony with the
lock and key theory.
First, the scent molecule fits into the receptor,
then those molecular vibrations take over.
Incredible as it seems, flies humans and dogs
may be smelling the sound of quantum biology.
Our sense of smell is fascinating and mysterious as it is,
but to think that when I encounter a particular scent,
and that sets off a whole wave of memories and emotions
in my mind, that it's underpinned, that it's triggered
by quantum mechanics I think makes it
even more remarkable.
(crows cawing)
The mysterious influence of quantum physics reaches
into every corner of the natural world.
In fact it inhabits the walls of every living cell on earth.
Because the latest experiments suggest a magical
solution to one of the greatest mysteries of nature.
The miracle of metamorphosis.
The transformation of a tadpole into a frog
has never been fully explained.
In little more than six weeks, the tadpole breaks down
then reassembles in its adult form.
But the big mystery is how it happens so fast.
When you think about it, there's nothing more
extraordinary than a tadpole turning into a frog.
Take it's tail for example.
Over a period of several weeks it gets reabsorbed
into the body and the proteins and fibers
that make up the flesh get recycled to form
the frog's new limbs.
But for this to happen, trillions and trillions
of chemical reactions work together,
breaking molecules and forming new ones
in a carefully orchestrated dance.
But the fibers that hold flesh together are very strong.
They're a bit like these ropes holding my raft together.
In order to dismantle the raft, I'd have to undo these
very tight knots.
You can think of it like this.
A tadpole is held together by long ropes of proteins,
knotted together by chemical bonds.
The bonds are so strong that they should last for years.
Much longer than the tadpoles entire lifespan.
So how can it turn into a frog in just a few weeks?
The explanation involves one of the most important
molecules of life.
Tiny widgets in all our cells called enzymes.
- The enzymes are the actual machinery of the cell.
They're actually the little machines inside cells
that do the chemical transformations
that are involved in everyday life.
They're absolutely crucial, and the reason they're
so crucial is because what they're able to do
is to accelerate chemical reactions by enormous amounts.
- Let me show you just how quickly enzymes get to work.
Inside this bottle is a substance called hydrogen peroxide.
You're probably most familiar with it as the chemical used
to bleach hair.
In fact I obtained this sample from my local hairdressers.
Hydrogen peroxide is also produced in the body,
and it's the job of the liver to get rid of it.
Now the way it does that is using an enzyme,
which breaks down hydrogen peroxide into water
and oxygen.
Now to show you just how quickly this enzyme works,
I'm going to do a quick demonstration.
I've got some liver here which I've chopped up in order
to release the enzyme.
Now watch what happens when I add this liver mixture
containing the enzyme to the hydrogen peroxide.
Watch how quickly the oxygen is released.
Just 100 grams of liver fired my rocket nearly 20 feet.
Liver enzymes make the breakdown of hydrogen peroxide
incredibly efficient.
It happens a trillion times faster.
That's a million million times faster
than it would otherwise.
In metamorphosis it's enzymes that dismantle
the tadpole's tail.
And that means breaking down an incredibly tough protein
called collagen.
- Collagen is one of the most important proteins
for the biological world.
It's the protein which actually gives that resilience,
that elasticity to tendons, to cartilage and of course
to our skin as well.
In the tail of the tadpole it provides the kind of scaffold,
it supports that structure.
Now when the tadpole is transformed into the frog,
what you need to do is essentially have an enzyme,
collagenaise, which will literally snip the collagen down
to small pieces and thereby take that scaffold apart.
- But how do enzymes break chemical bonds apart
so incredibly fast?
Let me show you why it's a problem only quantum biology
can solve.
Think of it this way, all these different parts of the knot
are like subatomic particles, electrons, protons,
that hold the different parts of the molecule together.
Now to untie the knot, enzymes have to move protons about,
but as you can see this takes quite a bit of effort
and a lot of time if there are many knots to unpick.
Physicists have a fancy way of saying
"put in effort to get something done."
They say you have to overcome an energy barrier.
Ok, here's my energy barrier,
and here's my proton.
To break a bond apart, it needs enough energy
to get over the barrier.
The trouble is, when we work out how long this would take
it's much too slow to break down a tadpole's tail.
But this is where protons turn into ghosts.
I wouldn't blame you for thinking that this is an idea
that a clever theoretician has come up with,
that it's just mere speculation,
something that we have no proof of but we do.
It takes place all the time.
In the quantum world protons don't have to go over barriers.
They can tunnel straight through.
Tunneling strikes at the very heart
at what is most strange about quantum mechanics.
It's like nothing we see in our everyday world.
The quantum particle can tunnel from one place to another
even if it has to pass through an unpenetrable barrier.
They're not solid objects like balls in our everyday world.
They have spread out, fuzzy, wave-like behavior
that allows them to leak through an energy barrier.
A particle can disappear on one side of the barrier
and instantly reappear on the other side of the barrier.
In nuclear physics, this effect is a proven fact.
Without quantum tunneling the sun simply wouldn't shine.
But I never thought I'd see it in a tadpole.
It's hard to stress just how weird this process is.
It's though I would approach a solid brick wall
and like a phantom disappear from one side and
reappear on the other.
The most important advantage of tunneling
is its speed.
It happens incredibly quickly,
much faster than if protons go over the barrier.
As a nuclear physicist, quantum tunneling
is my bread and butter.
Subatomic particles like protons do it all the time.
But what does this have to do with biology?
The answer is that without quantum ghosts,
the metamorphosis of a tadpole would be impossible.
Remember, chemical bonds are basically knots.
Tunneling unties them fast.
Have a look at these two knots.
On the face of it they look identical.
But there's a subtle difference.
This knot has the two short ends of the rope
on the same side.
Whereas this one has the two short ends on opposite sides.
Now you would think that wouldn't make a difference,
but it does.
You see, this knot is very hard to break,
whereas this one is easy.
Quantum tunneling turns strong knots into weak ones.
So in a tadpole, the entire collagen scaffold
breaks apart easily.
And finally other enzymes rebuild it in the shape of a frog.
The quantum tunneling of particles is one of those weird
features of the subatomic world that a physicist like me
is very familiar with.
After all, it's responsible for radioactive decay
and it goes on inside the sun.
It's the reason that the sun and all stars shine.
But to discover that it's going on inside every cell
of every living organism on the planet,
because every cell contains enzymes,
now that I find truly amazing.
Quantum biology casts its spell over every living creature.
We've seen that birds, mammals, insects and
amphibians are governed by the strangest laws in science.
But the most dramatic recent breakthrough concerns
the single vital process on which all these
forms of life depend, the conversion of air and sunlight
into plants.
This fine specimen is a a larix decidua or European larch.
It's about 100 feet high and right this moment passing
this side of the planet Venus is a bullet
with this tree's name on it.
The bullet is a photon, nearing the end of its long journey
from the sun.
It's ultimate destiny is to kick start a series
of chemical reactions that underpins all life on earth,
photosynthesis.
Every second of every day, 16,000 tons of new plant life
are created on earth.
For me, it's incredible to think that our existence
on this planet depends on what happens in the next
trillionth of a second.
The crucial first stage of photosynthesis is the capture
of energy from the sun.
It's nearly a hundred percent efficient,
vastly superior to any human technology.
But the way that every plant on earth achieves this
is one of the great puzzles in biology.
When it turned out that quantum weirdness
might hold the answer,
physicists could hardly believe it.
- It was like a revelation, it was very exciting.
I was used to working problems that were quite abstract.
I am a theoretician but I always related my theory to
experiments that were very clean in the lab.
Things that you can control.
But now finding out that the things that I knew
helped me to understand better how nature works.
Scientifically it was an inspiration to my life
as a scientist.
So I would say I fell in love with this field.
- Textbook biology says the color of green plants
comes from chlorophyll molecules.
Inside the living cells they absorb light from the sun.
This energy is then transferred incredibly quickly
to the food making factory at the heart of the cell.
The entire event takes just a millionth of a millionth
of a second.
When the photon hits the cell, it hits an electron
out of the middle of a chlorophyll molecule.
This creates a tiny packet of energy called an exiton.
The exiton then bounces its way through a forest of
chlorophyll molecules until it reaches what's called
the reaction sensor.
That's where its energy is used to drive chemical processes
that create the all important biomolecules of life.
The problem is the exiton needs to find its way to the
reaction center in the first place.
Textbook biology can't explain how the exiton does this.
Because of course, it doesn't know where it's going.
It just bounces around like a pinball in a process
called a random walk.
Sooner or later, it will pass through every single
part of the cell.
But this isn't the most efficient way to get around.
Because when the exiton eventually does reach
the reaction center, it's by pure chance.
If the exiton just blindly and randomly hops between
the chlorophyll molecules, it would take too long to reach
the reaction center and would have lost its energy
as waste heat.
But it doesn't.
Something very different must be going on.
The vital clue comes from recent experiments
that stunned the world of science.
Chemists fired lasers at plant cells to simulate
the capture of light from the sun.
They confirmed exiton wasn't bouncing along
a haphazard route through the cell.
- This original understanding didn't explain
what we were observing in the lab.
So the mystery lies in then what is the explanation
for what we are observing in the lab?
- [Jim] The solution is that plants obey the most famous law
in all of quantum mechanics, the uncertainty principle.
It says you can never be certain that the exiton is in one
specific place.
Instead it behaves like a quantum wave,
smearing itself out across the cell.
The exiton doesn't simply move from A to B.
In a bizarre but very real sense, it's heading
in every direction at the same time.
It's spreading itself out as a wave,
so that it can explore all possible routes
simultaneously.
This strikes at the very heart of what's so strange
about quantum mechanics.
The exiton wave isn't just going this way or
that way, it's following all parts at the same time.
That's what gives it such incredible efficiency.
(wave reverberations and stringed instruments)
The beauty of it is, if the exiton is trying every route
to the reaction center at once, it's bound to find
the fastest possible way to deliver it's energy.
It's hard to express how incredible this discovery
seems to physicists like me.
Biological cells are full of the random jiggling
of billions of atoms and molecules,
but somehow exitons maintain their form
as beautiful perfect quantum waves,
transporting the energy that guarantees life on earth.
- It opened a whole new scientific path for me,
and I really enjoy the fact to be able to understand fully
what is happening in the plants you have to interact
with scientists that have completely different approaches,
like biologist and chemists, but we all have to
come together to actually understand
what is the relevance of this.
For me this is one of the most exciting parts of this field.
- [Jim] Real scientific experiments leave no doubt.
The strange hand of quantum mechanics has shaped
the entire living world.
- It's not a surprise that you should find quantum tricks
being used in biological systems.
The reason is because they're better.
- Quantum entanglement is normally seen in the tightly
controlled conditions of the physics lab.
But now we know that robins use it to navigate with
extraordinary precision.
Quantum vibrations mean our noses listen to chemicals,
enhancing our perception of the world around us.
The living cells of all animals depend on protons
that vanish and reappear like ghosts
speeding up the vital processes of life.
And photosynthesis reveals the big picture,
a shimmering world where quantum waves capture
the sun's energy in an instant.
- Sometimes people say but physicists have been looking
for this for decades.
Well biology has had millions of years.
- The ultra-modern science of quantum mechanics
is an ancient fact of life.
For the end of my journey
I want to take these ideas to their logical conclusion.
Of course as a scientist, any speculations I have
need to be backed up by careful experiments.
So I want to concoct a thought experiment
that helps me to answer the biggest biological question
I can think of.
Does quantum physics play any role in the mechanism
of evolution itself?
In 1859 Charles Darwin stunned the world with his theory
of evolution by natural selection.
He went on to explain the differences between humans
and other apes.
One hundred and fifty years later, there's no doubt
that Darwin's theory accounts for every living organism
on land or sea.
But I'd like to explore the latest extraordinary
interpretation of his ideas.
Could there be a quantum theory of evolution?
(dramatic orchestra music)
Can quantum evolution explain how the snail
got its shell?
The snails I'm used to seeing in my back garden
tend to have rather bland, boring shells.
So have a look at this beauty.
The patterns on its shell very perfectly match
the lines on the stem.
It's called a banded snail, cepaea nemoralis
and the pattern isn't there by accident.
Come and have a look at this.
Less well adapted snails are more likely to be found here.
This stone is called a thrush's anvil.
The song thrush is the snail's main predator.
It catches the snail and smashes it's shell against
the stone to get to the snail.
Now all I can see here is that there aren't many
banded snail shells, suggesting that its colors
camouflage it very well, hiding it from the bird.
Darwin's theory says that evolution depends on variation
within a species.
Snails with camouflage are more likely to survive
and reproduce,
passing on their shells to the next generation,
so that the species as a whole becomes better adapted.
So variation, the random differences between snails,
is the driving force behind their evolution.
Now all species evolve and adapt to their environment,
but the question I'd like to explore is whether
quantum mechanics plays a role in this.
The only way to find out is by scientific experiments.
So my adventures in quantum biology finally bring me home
to the University of Surrey.
Here in the laboratories I'm planning a new analysis
of the most celebrated molecule in science,
Deoxyribonucleic Acid or DNA.
Its double helix holds the genetic code
for every living organism.
It's a remarkable fact that Darwin himself
had no idea what created variation in the species.
The structure of DNA wasn't discovered until 1953
by Francis Crick and James Watson.
The most famous feature of DNA is of course its
beautiful double helix structure,
but that's just scaffolding.
The real genetic secret lies in between.
The four different colored molecules are called bases.
The color code on one side, say blue, red, blue,
forms a gene the parents pass on to their offspring.
A gene is a bit like a jigsaw puzzle.
It fits together like this.
A full strand of the double helix forms a colored pattern.
But the other strand always pairs up the same way.
A blue base always goes with yellow and green always
goes with red, because only those colors have
the right shape to fit together.
What Crick and Watson realized was that this provides
a mechanism for passing on the genetic code.
When cells reproduce, the two strands of DNA separate,
ready to be copied.
But red still goes with green,
and yellow still goes with blue.
So bit by bit the cell creates two new strands.
Two perfect copies of the entire genetic code.
So far there's no genetic variation.
This new copy is identical to the original.
But here's the interesting bit,
during the copying process something very important
can happen.
Sometimes mistakes creep in.
They're called mutations.
Let's have a look at these two bases here.
The two prongs that hold them together are subatomic
particles, they're protons.
They're basically the bonds between the strands of DNA.
These protons can jump across to the other side.
If the strands split when the protons have jumped across,
they find themselves in the wrong position.
Now this red base will no longer bind to a green base.
Instead it has to bond to a yellow base.
Slotting this back in, we see that now this copy
is no longer identical to the original because I have a
yellow base here instead of a green one.
We've brought in a genetic mutation.
Jumping protons would change the snails DNA.
It could make a new gene for camouflage shells.
The question is, how do protons jump?
It's my belief that quantum spookiness can take over.
Now for these mutations to take place, the protons
have to overcome an energy barrier,
and if you remember what happened with enzymes
well you can probably guess what's coming next.
Protons can behave as if barriers don't exist.
They tunnel straight through.
But does this ghostly effect really happen?
My colleagues in biology are already looking for the
first evidence of quantum mutations.
- Biologists didn't even really know about quantum
mechanics, so when you tell them that particles
can be in two places at once they kind of say,
"Well not in my cells they can't."
Our experiments involve samples of bacteria.
The first sample is prepared in normal water,
containing hydrogen nuclei or protons.
When the bacteria reproduce,
we simply count the mutations.
But if our theory is correct,
then we should be able to change the rate
at which mutations occur.
Remember how we texted the quantum theory of smell?
What if I replace the proton
with it's big brother the deuteron.
This is the nucleus of an atom of deuteron.
Now crucially a deuteron is twice as heavy as a proton
and this should influence how easy it is for the deuteron
to quantum tunnel.
Quantum mechanics is full of surprises.
Protons tunnel easily, deuterons don't.
These heavier particles are much more likely
to bounce straight back.
So the second sample of bacteria is prepared in
heavy water, which is full of deuterons.
Our theory says you should get far fewer mutations
and so far the results are extremely encouraging.
- The preliminary experiments that we've done
gives us a hint that the mutation rate is indeed depressed
in deuterated water.
We find that it is lowered, so my hunch is that we're right,
but we'll have to wait a little while before we're sure.
- Final proof lies in the future.
Even if we are right, quantum tunneling is a rare form
of mutation.
But our results promise hard evidence for a new
explanation of one of the most fundamental
processes of life.
Even the merest possibility of a new quantum mechanism
for evolution itself is tremendously exciting.
In fact the story of quantum biology is only just beginning.
What the frog, the robin, the fruit fly and the tree
have shown us is that real quantum effects are going on
in nature all the time.
And if there's anything we've learned from the history
of quantum mechanics it's this,
we can never be certain where new discoveries
will take us next.
Quantum biology is a revolution in science,
but it's time I got back to the physics department.
(dramatic orchestra music)