Original subtitles

It's time to talk about food.

Now, most organisms eat other organisms,

like plants or animals that eat plants.

Don't eat me! You've got a whole cow there.

Lamb chop?

No, I ate before the show.

Only humans eat what we call food.

We've made it, we've bred it -

it's stuff that's deliberately created to be eaten.

And it's the variety and complexity of our diet

that sets us apart as a species.

But, over the last few decades,

our food, and the system that produces it,

has changed beyond recognition.

And this has created a few problems which we're going to need to solve.

APPLAUSE

Welcome to the Christmas Lectures from the Royal Institution,

supported by CGI.

I am Chris van Tulleken,

and tonight I'm going to take you through a history of eating,

especially human eating, on planet Earth.

Will our timeline please stand up?

So this is a timeline that takes us from the formation of planet Earth

4.6 billion years ago.

Give a little wave.

And it goes all the way through

to what you ate for breakfast this morning over here.

And our story begins...

Let me run up here.

Our story begins with one of the first meals

eaten on planet Earth.

I'm going to pass it down, and we want that to get

to about 4 billion years ago.

We're going to represent that with a bowl of rusty soup

on the timeline.

And to help make this meal,

I want you to please welcome

the director of the Institute of Making,

an expert materials engineer, Dr Zoe Laughlin.

APPLAUSE

Talk me through it, Zoe.

OK. This represents the Earth at the dawn of life.

OK. This is the ocean.

It would have been quite hot,

so it could have been boiling at some point,

but it was remaining liquid with an insulating layer of CO2.

OK. So here we've got some dry ice in the water,

creating CO2 gas,

but also dissolving into the liquid itself.

The sea would have been very rich in CO2.

We also have a volcano. Of course. Of course.

It's a very hostile environment. OK.

But these are the conditions for the first meal.

All right.

So you're going to make this first meal.

OK, I will. A few safety specs required.

Of course I'll need safety goggles.

And, like any chef, I need a blowtorch.

For, like, you know, caramelling the top?

A little bit of creme brulee on your meal. OK. Great.

And this is going to be like one of those puddings with a hot centre.

Is it a baked Alaska? What am I thinking of?

There will be a molten centre, this is true. Great.

But, well, let's see how much you want to eat it.

OK...

I'm going to light magnesium strips inside this volcano,

all being well. Now...

OK... Whoa!

Whoa! Sparks are flying.

OK... Oh! Whoa, whoa!

OK. So...is this the meal that's pouring out the bottom?

That is the food coming out of the bottom of the volcano,

into the water.

I'm going to stand up behind some audience members.

It's still ablaze, even though it's underwater.

Can we get it? What is it?

Now, be careful, because I think this is still hot.

Let me feel the tank. Yeah, that's warm.

So I think the next job is for you to fish for your supper, please.

OK. In you go.

Lower this in.

There we go. OK...

And it's stuck to this.

There it is. There it is.

Your meal!

OK, so this... It's stuck to the magnet. What is this?

This is iron.

This is raw iron?

Raw iron. Pure iron.

What we've done here is a thermite reaction,

so we've mixed iron oxide and aluminium powder,

and, with the magnesium ignition, it's created an extremely volatile

exothermic reaction - over 2,000 Celsius -

that generates molten iron

that was dripping into the water and then solidifies.

And there you have it, pure iron.

This iron would have been the food for some of the very first

microbes on Earth.

Early life would have been eating this iron,

breathing the carbon dioxide,

and excreting out a rust-like substance.

And they've been doing this in the sea,

and all of that detritus would fall to the seabed

and form strata of iron oxide.

And that's the seams that we're mining still to this day

to create objects out of iron, like the railings of the building

we're in, making our modern world.

It's come from early bacterial poop that's sedimented,

and then we've turned it back into iron to create our world.

Yeah. That is incredible. And this is still going on today.

So, in fact, if I just grab this bicycle, this trike,

you'll see... What is this? Well, this is actually my own trike.

Is it really? 40 years old this Christmas.

And this is the rust that's, you know, occurred over time.

But this has occurred because we have oxygen in our atmosphere.

So it's not the same reaction,

but those same microbes are in there,

feasting on the iron and taking advantage of that oxidation.

So the first life is eating stuff that's never been alive,

and those bugs are still at work today? Correct.

That is fantastic. Um, Zoe,

an amazing demonstration, a terrible meal,

but I think there is more to come!

Everybody, Dr Zoe Laughlin!

CHEERING AND APPLAUSE

So, can our timeline please stand up again?

And I'm going to put Zoe's rusty tricycle...

Let's put the rusty bike right back here at this end.

Because those autotrophs,

the life that takes inorganic material

and turns it into organic material, living things,

those bugs, those bacteria, they're still alive today.

So we've got our rusty soup at that end.

And in the history of eating on Earth,

something happened pretty quickly, we think. After that, life existed.

So, we've got bugs starting to eat things that have never been alive.

And pretty shortly afterwards, life figured out a short cut.

Bugs started to eat other bugs.

So let's put that there.

So very, very quickly,

life figures out it's easier to eat other life.

And this sets up something called an arms race

because we've got life needing to eat

and life that does not want to be eaten.

And they have to evolve so that one can keep eating the other

and one can keep avoiding being eaten.

So we're going to hustle through the next few billion years.

We get the evolution of complex cells somewhere... There we go.

We get increasing complexity in cells.

1.5 billion years ago, approximately,

we see the evolution of multicellular life.

Life is becoming more complex because of that arms race.

Then, 530 million years ago,

approximately, the evolution of primitive fish.

And from those primitive fish, a creature called Tiktaalik,

a fish with legs,

that started to come out onto the land.

After Tiktaalik, we see shrew-like mammals 225 million years ago.

And it was these creatures that survived

the age of the dinosaurs and from which the age of mammals flourished.

And then we're going to move from the shrew-like thing

to the early apes,

around 30 million years ago there.

And, finally, I want to get us to 2.5 million years ago.

Now, 2.5 million years ago, it was a really, really important

moment in human eating.

These are the apes we're descended from,

and Zoe has prepared a meal

that apes at this time would have been eating.

So we now have a 2.5-million-year-old meal.

Is that right, Zoe? Yeah, I'm really pleased with this one.

I think you're going to enjoy it. OK.

This is better than the raw iron? Yes.

First things first, Chris, you need to dress for dinner, please.

What is this? Like, clothing of the period?

Yes, it's a special occasion. OK. A little jaunty number.

Can you do me up? Quite right. There you go. Lovely.

Now, you're hungry? Yeah. Right.

Here we go. First off, we have...

..some tubers. Right...

So some raw root vegetables covered in dirt.

OK, great.

What goes with them?

Well, the piece de resistance...

Are you ready, sir? Mm-hm.

Your lamb!

A leg of raw lamb? Yes.

You haven't cooked it at all?

No, I mean, I've caught it, killed it,

butchered it, skinned it.

It's ready to roll! You don't expect me to eat this? Raw. Go for it.

Tuck in, please.

OK...

This is real raw lamb.

OK, er... OK, I'm going to have a go at that bit.

AUDIENCE GROANS

Please do not try this at home!

Raw meat contains parasites,

bacteria.

But Chris is an infectious diseases doctor,

so he has informed consent here.

He knows what he's doing in this demo. Do I?!

I think your agent signed something. I think it's fine.

Well, I'm not doing enormously well, I have to say.

What I'm struggling with is this white connective tissue.

The tendon. I mean, that's a bit of the tendon there.

Yeah. Can't make any progress at all. This is extremely tough stuff.

So this is attaching muscles to bones

and, when the muscles contract,

it's, you know, articulating those limbs. Right.

So this is an example of food that does not want to be eaten.

This hasn't evolved to be eaten. Yeah.

And you mentioned the tendon there.

I've actually prepared a little demo on tendons for you,

but first I need you to wash your hands, please.

OK. I'm going to put that to one side.

I think what I can confidently say, and I've never tried that before,

is I could be with that all day,

I wouldn't really get anything useful out of it.

I cannot make anything... Then I don't know if you're really trying.

I'm going to go and wash and change. Thanks, Zoe.

OK, I'm going to need a volunteer for the next part.

Oh, my goodness, loads of you!

Right. In the middle with the fringe and the T-shirt.

Come on down!

APPLAUSE

Hi, there. What's your name?

Amelia. Amelia.

Welcome to the stage, Amelia.

And lower the tendon!

Here we go.

OK, Amelia, what I have here

is a small section of tendon from the foot of a cow.

Now, this is very tough material,

but we really want to know how strong it is.

To test that, I'm going to hang you...

No, I'm going to get you to attach these weights to the tendon.

OK?

So let's begin, just with a kilogram.

Hi, Amelia. Did I get the name right? Yeah.

Good. OK, so hang them up.

How's that? It's not too heavy, is it?

So we've put a carabiner through the tendon, so just hang

that on the piece of metal.

Lovely.

OK. OK. 1kg, no problem.

Let's have a look. The tendon isn't extending.

Three kilos.

I mean, this is...nice.

Nicely done. Nothing much. No problem there.

Four kilos, no trouble. I think we take this to the next stage.

Let's go 15kg.

OK.

OK. Now, Amelia, I want you to feel how heavy that is, OK?

I'm not going to... Put both hands under, OK?

Yeah. It's heavy, isn't it?

Right, let's stand back a tiny bit for this one.

Chris, you can have a go at this one. OK.

OK. I can see the whole kind of rig-up stretching,

but the tendon, not so much.

Maybe a millimetre or so.

It seems happy enough.

Let's go for bust.

That's 15. Let's add on... 20 kilos?

25 kilos?

So this is now going to be the same weight as you, give or take.

There you go. You got that?

Yeah. Yeah, yeah.

So there'll be a good 40kg on here. Easily the weight of a child.

Right...

Oh...

OK. You're on.

OK, I'm going to load that very gently.

Oh. So, again, most give from the rope, I think, more than the tendon.

Yes! Yes! The tendon is holding!

This is the power of tendons.

Look at that. This is so strong.

In fact, if we took a bigger tendon,

we could hang it from the ceiling and suspend a car.

Really? So we're limited mainly by the strength

of the theatre ceiling at this point,

more than the strength of the tendon? Yeah.

So we could all hang off that?

You, me, Amelia, swinging away.

So brilliant work, Amelia,

but I think you do lose this first round of

human versus tendon, don't you?

It is 1-0 to the tendon! Tendon!

And I think, actually, what we've seen really clearly is

that's why I can't eat the lamb,

because tendon and those connective tissues are incredibly tough

and hard to bite through. Yes.

Brilliant work. Thank you very much. Thank you, Zoe. Thank you, Amelia.

APPLAUSE

I want to now look at the anatomy of an animal

that might have been able to eat that meal better than me.

To help me, I want to welcome the head of Heritage,

who looks after the museum and the archive here at the RI.

This is Charlotte New.

Now, what I've got here is two skulls.

This is a modern human skull.

OK? So very much like yours.

And this is Australopithecus,

who lived around 2.5 million years ago

and was eating that meal that we just saw.

And I want you to look at the differences between these skulls.

OK? First of all, the most obvious thing is the modern human

has an enormous brain compared to your great-great-grandparent.

OK, but it's our great times 120,000 great-grandparent.

So how does this creature evolve into this one?

Well, I want you to look at what the skulls are made of,

particularly at the jawbone.

OK?

Because the bones on this head are much, much bigger and heavier.

And this is particularly obvious when you look here.

If you see, the modern human jaw is smaller,

it's much more fragile, the teeth are tiny.

And when you're comparing those jaws,

remember, this head is all about processing food

that's hard to chew with the muscles and the bones.

Now, both of these animals have to be born through

a human pelvis - a ring of bone -

and that constrains the size of the head.

And this is the problem.

The space in your heads is basically taken up by three different things.

Your brains, your muscles and your bones.

The space in the Australopithecus head

is mainly occupied by enormous chewing muscles here and here

and these very, very heavy bones.

It needs that chewing apparatus in order to eat.

The human head is occupied -

the modern human head - the space is occupied by the brain.

So Australopithecus is in a trap.

How does Australopithecus escape the trap and become a modern human?

I know, Chris, I have the answer for you,

and it lies at the end of this very large plastic tube

that many of the audience members are holding for me.

So I've been filling this with highly explosive gas,

and I'm going to set it on fire any minute now.

OK... Lights down, please!

Here we go. Three, two, one!

Here we go.

Here it comes. So magical, isn't it?

Whoa! Whoa!

APPLAUSE

So the answer is fire.

Zoe, that was an amazing demo.

Now, people might be tempted to try that at home.

Would that be a safe thing to do? Absolutely not.

Do not try doing that at home.

So, 2 million years ago, when early humans learned how to

harness fire, everything changed.

And I think it's time for another round of human versus tendon.

Brilliant. Lower the tendon!

OK. So this is the original tendon in here?

This is the original tendon.

If you remember, this held 40kg, no trouble at all.

OK. Now we're going to swap out the tendon.

So it's from the same part of the cow.

The only difference is this tendon is now cooked.

So, at around 40 degrees,

the proteins in the tendon start to denature.

They change. At 50-60 degrees,

they actually gelatinise

and become much, much more tender.

And you can see that difference.

If we look at this tendon now,

it's actually feeling all kind of wibbly wobbly, rubbery.

Shall we load it up? Load it up.

Let's begin with a kilogram again.

That's what we started with last time.

OK, here we go.

Just put that there, like that.

Whoa! OK!

Oh! So actually we can see this...

In fact, I think I can just...

Yeah, I mean, this is now so much weaker

that you can bite through this no trouble at all.

Can I actually do that? If you want, you're the doctor.

Yeah, I can do that. Slightly salty.

I'm not going to pursue that.

I don't quite know how this was prepared, but it was...

You cooked this for some time?

Yeah, for an hour at about 70.

OK. You know, it's...it's jellified.

It's not totally dissolved.

You could keep going, and that's how you get stocks and things,

by the dissolving of those connective tissues

and that collagen that adds to meaty broths.

So, Zoe, that is a brilliant demonstration of how the material,

the physical structure of food and tendons,

but other foods as well, is changed by cooking,

making them easier to chew.

Zoe, thank you for another brilliant demo,

and I think another meal is upcoming!

Zoe has beautifully explained how cooking changes the structure

of food, its engineering properties,

making it easier to bite and chew.

But cooking brings other advantages too,

and this was first shown by a team at Harvard University.

And for our next guest, I want to welcome

a crucial member of that team of scientists.

But you need to clap very quietly for them.

Please welcome Monty.

Monty, being held by Mark. Hi, Mark. Hi, Chris.

How are you going? How are you doing? Good. So talk us through.

Who is Monty? So Monty is a Burmese python.

Python bivittatus. They're a constrictor.

That's how they eat their food. I can see that!

Yeah... No, they're just.... That's just holding on.

But they have a real immense power.

OK. Now, can I hold Monty? Sure.

How do I do it? We'll have a go. OK.

It's a de-wind, isn't it?

How heavy is Monty?

Er, it's not so much the heaviness. It's the... It's the weight -

it's the power. It's the power. OK. Hi, Monty.

Hi, Monty.

Oops! You'll feel...it'll transfer to you.

So the reason we've got Monty here... Do stay close, Mark!

LAUGHTER The reason we've got...

The reason we've got... Immensely powerful! Immensely powerful.

Um, the reason we've got Monty is because the team of scientists...

Oooh!

..the team of scientists used...

When did Monty last eat? Just let go of your hand.

So I've been putting it off -

putting it off to keep him for this show. OK!

So he's going to have a couple of rabbits tomorrow.

Great. Great. Good.

And, um...

So the team of scientists used Burmese pythons, like Monty,

and they did an experiment.

They fed snakes like Monty two different meals.

One meal was raw chunks of meat, like snakes normally eat,

and the other was ground cooked beef.

And what they found was that the snakes used 25% less energy

to digest the cooked, chopped meat,

so there was more energy to start developing the human brain.

We start to see how cooking releases Australopithecus from the trap.

But cooking brings other advantages as well, doesn't it, Monty?

Because it also cleans food

and so, when you cook meat, you kill all the parasites in it.

It's very nice...

Um, do you want...

Does anyone want to see? Do you guys want to see?

Come over here. Who wants to see? Do you want to have a little...

You can... Can they touch Monty?

Absolutely, yeah. And what would be the largest meal Monty would eat?

You know, compared to one of these guys?

Oh, a big... Maybe ten-foot alligator.

OK. Oh, really? OK!

So bigger than these three?

Yeah. OK.

But humans are fairly safe because our shoulders get in the way.

So, cooking kills parasites.

Parasites, if you're fighting them the whole time,

like all the other carnivores were having to do 2.5 million years ago,

fighting those parasites also takes a lot of energy.

So cooking starts to release a huge amount of energy

for brain development.

Now, why did they use Burmese pythons, or pythons of any kind?

And the reason is that you can put a snake in a tank

and measure everything about it very easily over several weeks.

Monty, you've been an incredible guest,

and I think I'm going to gently hand you back to Mark

so that we can get on to a wider discussion of food processing.

Can you...? Are you all right getting him off me?

Done. Lovely stuff. Monty and Mark!

Are they OK to applaud? Absolutely, yeah.

Snakes are deaf to airborne noises, so there you go, he's in the air!

All right. Big round of applause!

So the first processing is cutting and cooking,

happening around about 2 million years ago.

And then processing really, really took off.

It changed our anatomy, our physiology, our genetics.

And for hundreds of thousands of years of our evolution now,

we've been chopping and grinding and pounding and smoking

and salting and fermenting.

Humans have to process our food.

If you look at our tiny little jaws, our small teeth,

our very minimal chewing muscles,

we are the only animals that cannot survive

without food processing.

Other animals use their teeth and their guts.

We do it with tools and fire.

Now, we started processing wild food

and then we started domesticating animals and plants

and processing them.

And that was the dawn of farming.

So I want to go back now to 14,000 years ago on our timeline,

the dawn of agriculture.

And it's when we started to make foods that we recognise today.

And, Zoe, I think you have some of these foods here.

Yeah, right.

Ready for our next meal.

But I'm going to need to enlist the help of the audience

for some collective food processing.

So I have two liquids in these jars.

Chris, if you take one, we're going to hand these out.

We'll start at the back and we want you to pass it along

so it comes down to the front, just on the two sides.

But what I want you to do when it comes to you is shake.

Like, really, really shake.

No, Chris. Come on! Really shake!

Da-da-da... The full enchilada!

Yeah. You've really got to go for it.

And then, when your arms are tired, pass it on.

So about ten seconds until you're exhausted? OK!

Up to the back. Shake and pass it on.

OK, we can start with you, and it will snake its way back

through the audience.

Really up high so we can all make sure you're doing it properly.

That's it! Now I'm going to draw your attention

to this ancient food processing tool.

This is a saddle quern. It's over... A what? Saddle quern.

A saddle quern? 9,000-year-old tool. OK.

And we need two volunteers from the audience.

Let's have stripy top and Fair Isle cardigan.

Come on down.

Lovely. What's your name?

Fiona. Fiona and...? Sam.

Sam. Sam and Fiona. OK.

What I'm going to do is put you to work.

One of you, please... Sam, you sit here first,

at this end. You'll both have a go at this.

Come and sit on the floor, facing this way.

Fiona, you're in charge of this sack, right?

Two hands on the stone with thumbs tucked up

so you don't crush yourself.

Don't grind your thumbs, Sam. We don't want that.

Yeah. And what you're going to be doing is grinding wheat

that Fiona has in her sack.

You just sprinkle in a few more wheat grains.

Now, this might feel like hard work,

but I promise you, I mean, I've done the hard work for you.

I've domesticated the wheat.

I've grown it, I've harvested it.

All you've got to do now is please grind this,

fill this sack with flour,

and then we'll be able to make some bread.

The way I'd understand this is

now Sam and Fiona have started to chew for the whole community.

Australopithecus was having to do this kind of stuff

with its jaw muscles and its molar teeth

if it wanted to eat the seeds at the top of a stalk of grass,

which is what wheat is,

and now these guys are doing it for everyone.

Yeah, it may feel like hard work, but it's actually highly efficient.

And not only that, you're producing a new material.

You're making flour.

Once you have flour, you can start making breads,

cakes, Danish pastries...

All kinds of things start to happen.

OK. How are you getting on? Do you want to swap round?

Yeah. OK, have a swap.

How's this other stuff doing?

Shake it! Shake it hard. Pass it on. We've got to get it to the front.

Right, let's have a look. OK.

Not bad. How does it feel?

It's quite hard, but the flour is coming through.

The flour is coming through.

You're actually producing a fair amount.

I mean, not yet a teaspoon.

So you've got a way to go before you fill your sack.

But that is flour.

This is magical stuff.

This will now last much longer once it's dry than the wheat on its own.

And, as you say, a brand-new type of substance,

one that previously, you know,

it was digested as soon as it was made in our mouths.

OK, I think we should get the other stuff down. Yes.

Do you think it will be ready now? Well, we can try.

Let's say thank you to Sam and Fiona first.

Thank you. Where's that jar?

Keep going, gang. Come on, come on, come on, come on!

Pass it straight down.

Shake it as you go. Shake it as you go.

There we go.

Now, yours is still quite sloshy.

I think mine feels... Mine feels funky.

Oh, slosh and funk. Try it.

I'm not sure. That feels more solid. Have I got to keep going?

Yeah, keep going with that one for a bit.

Well done, this side.

OK! So what... Can anybody think

what we might be trying to do here? At the back!

Make butter. Make butter. Correct!

What is bread without butter? Indeed!

It's very sad, that's what it is.

But this is an ancient process.

Let's have a little look inside. We can...

Now... OK.

This liquid, this is the whey.

Oh, and there we have... Oh, look at that! ..our butter.

And we really did start with cream.

Yes, so what's happening when you shake that container

is the cream is smashing into itself inside

and the fat globules are coming together -

they're coagulating and they're amassing so much so

that they then amass to form that lump, which is butter.

Transformative stuff.

Again, it's another new food product.

Zoe, a fantastic demonstration. You're welcome.

Thank you very much indeed, and I think there's more meals to come!

I'm just going to take a scoop of butter here.

I just want a little bit. Just want a little bit.

Butter is extraordinary stuff

because, when humans first domesticate other mammals,

it seems obvious that drinking the milk would be a good idea.

But milk, when they first do this,

they're doing it in very hot, tropical places.

Milk spoils within hours and then becomes very dangerous.

The advantage of butter is that you've taken most

of the energy out of milk.

You've taken the fat and, because it's a solid,

the bugs can't move through it.

And so you're preserving the energy.

So let's put the bread and butter on the timeline.

Here we go. Bread and butter.

And we're down to the last few millimetres.

I'm going to clip that on there.

In fact, these are going to overlap.

Um, this is the dawn of what we might think of as modern food.

Can you just hold them? Thank you so much.

Great.

So, from the dawn of agriculture,

we start to eat a greater variety of foods.

6-10,000 foods start making up the human diet,

and farming and food processing gradually become more mechanised.

We start with stones, and then it becomes driven by animals,

and then big machinery,

and farming and food processing goes from being done at very small scale

to being done at very, very large scale

by industrial farms and factories.

And now almost all of our food is bread -

grown, harvested, processed -

and then sold by extremely large global companies

that form part of a huge industrial global system.

And what's really important to say is this has brought

a massive number of benefits

because the corporations that grow and produce our food

weren't just making ingredients any more -

they weren't just making flour and tins of corn -

they started making finished food products

that had previously been made at home.

And these products were very, very cheap.

They were convenient, they were quick to prepare.

So all kinds of things started happening.

A burden was taken off women,

who can now enter the workforce after World War II.

So the industrial food system brought many, many advantages,

but it also brought some problems.

To help us understand the modern industrial food system,

in more detail, I want you to welcome a public health expert

and academic from City St George's University of London.

She's also a former food engineer and commodity trader.

Please welcome Dr Yanaina Chavez-Ugalde.

APPLAUSE

Yanaina, you've brought a machine with you.

Yes. And, of course,

this is an extreme over-simplification

of the food system

and, of course, the food industry that I used to work for.

OK. So you very well explained

that humans used to consume thousands of species,

but in the past few years we have only based our foods in four crops.

Which are...

And I'm sure you've seen this before.

It's like edamame. Soy.

These are soybeans because I think we recognise these -

people will have had these and thought of them as edamame.

But they are, they're soybeans?

Soybeans. We also have wheat. Wheat.

We have rice...

..and we have corn.

OK. So you won't believe this

but, today, 50% of calories come from wheat, soy, corn and rice,

and 20% of our calories come from corn.

Now, this is a bit surprising

because I want to ask all of you, in the last week,

how many of you have eaten a fresh cob of corn,

probably spread with a bit of butter?

If you've done it in the last week, put your hand up.

OK, so some corn eaters here,

but I don't think we're at 20% of the audience.

I don't think it seems like 20% of people's calories

are going to be coming from this?

Exactly. It's because we don't only consume corn in this shape or form.

That's why I brought my friend, the Foodamatic 3000.

So, let's see what happens.

MACHINE RATTLES

LAUGHTER

Amazing!

So talk us through this.

We have... Let's start with corn starch.

Corn starch - I'm sure you have seen it -

it's a thickener,

and you can use it in yoghurts, sweetened yoghurts.

It's very common to find it there.

I feel like I see it on ingredients lists the whole time.

Yes, it's very prevalent in food. OK.

What else have we got? So we've got starches.

That's carbohydrates.

We have high fructose corn syrup,

which is a substitute for sugar.

It's way sweeter than sugar

and it's way cheaper than sugar.

OK. So we can get sugar out of corn as well?

Yep. Sorbitol, which is also a substitute of sugar.

But as you see, it's not that gooey.

It's just another... yet another powder.

And it's very good and very highly used

in, um, sugar sweetened beverages.

So another sweetener.

We have maltodextrin that sometimes is used in breads as well.

Another sweetener, another palatable thing that

your taste buds really, really like.

Starchy, carby stuff.

And you'll see this on lots of ingredients lists, won't you?

Yeah. OK.

And dextrose, usually seen...

It's also kind of gooey.

..in bread. OK.

So another kind of sweet sugar.

So corn's pretty good for the carbs.

And one more. We also have corn oil.

It's a vegetable oil.

And you can use it and mix it as a fat substitute for many,

many of the products that we see packaged

in our food system, the supermarket.

So I'm starting to understand how, by transforming the corn,

you extend its shelf life, you reduce some costs,

and now we can have corn in our breakfast cereal.

We have it in our mid-morning snacks.

It's in our sandwiches.

It's in our condiments, in our ketchup, in our wraps.

We start to see corn in everything, and presumably we're also feeding

some of it to the animals.

Yes, we have food and we have feed - food for animals

that then we eat, so we end up eating corn in this,

but also in the meat you were trying to eat, if that lamb ate some corn.

OK. So we're eating corn in lots of different ways.

What other kind of things do we put in the Foodamatic?

Well, you put seven or eight other crops in this friend,

and you get 75% of the calories.

Really? So our global calorie intake

is now coming from a tiny number of different species,

all of which can be broken down into these kind of pastes and powders.

Absolutely. OK.

This is not necessarily a bad thing.

It's driving down the cost of food,

and there are some efficiencies that come with all this.

Absolutely. And you plant one crop

on one piece of land and you get all of this.

OK, Yanaina, thank you very much indeed.

Stay around with the Foodamatic 3000 because we may

need it again in a second. Grand.

Thank you! Thank you very much indeed.

APPLAUSE

While Yanaina has been industrialising the food system,

Zoe has been setting up a small traditional ice cream business.

So, Zoe, talk us through what you've been doing.

This is the next meal. Yeah, I'm really proud of this.

I'm slightly more excited about this one than previous ones!

I come from a long line of pudding lovers and makers,

and I'm going to make for you a firm family favourite,

which is strawberry ice cream.

What's not to love?

Three ingredients - strawberries,

a little bit of sugar, just to bring out

the best of the strawberries,

and cream.

Now, Chris, if you wouldn't mind just giving that a good stir,

make sure all the ingredients are nicely incorporated.

Just three ingredients in your ice cream? Yes. OK.

And I just need to put on some safety gear

because I'm going to freeze it by using the old favourite

of the Christmas lectures, liquid nitrogen.

And not a traditional way of making ice cream necessarily,

but it's just a very quick way of doing things, isn't it?

It is. I'm not wearing safety gloves,

so I'm going to retreat slightly.

You stand back. Right, let's pop some in. Here we go.

POPPING AND CRACKING What are we hearing here?

So this is the rapid formation of the ice crystals.

So liquid nitrogen is -196 degrees Celsius,

so extremely cold.

And the trick to delicious ice cream

are tiny ice crystals,

and you make those by forming them fast.

There's our ice cream.

A little bit more maybe. Give it a good stir.

And it's ready!

I mean, I blow it to warm it up a tiny bit,

but you can try it if you want. Blow it to warm it up! OK!

Hold on. Let me just pull off a bit here.

Yeah. It's good to go? Give it a little blow to warm.

Yeah.

Mm... It is cold!

LAUGHTER

It's cold. I'm going to style this out.

But tell me that's not delicious? It...

I can't taste anything!

No, it is, absolutely! It's really delicious.

So, your business, this little business you've set up

with your three-ingredient ice cream,

you must be going gangbusters.

It must be absolutely brilliant. They're queuing round the block.

Are they? So are you going to expand? You can go global!

There is a problem, which is it doesn't travel well.

What do you mean?

You can't get it home because it melts by the time it gets there.

So you can eat it here, but you can't take it away.

Is it cheap to make?

Well, it's comparatively expensive, if you think we're using

full-fat double cream, strawberries and sugar -

they're not the cheapest ingredients.

Strawberries are a bit seasonal. Can you get them all year?

You can't get them all year. You'd have to mix your fruits up.

You know, it can be expensive, but it's quality stuff.

Brilliant, OK. Well, you've actually given me an idea.

Yanaina, do you want to come back?

Because what I'm wondering is Zoe's doing a great job over there

serving her community,

but do you think we could use the Foodamatic 3000

to make ice cream that was a little cheaper

and easier to transport?

Absolutely. Guaranteed.

OK. How are we going to do it?

I'm going to show you.

OK, some ingredients.

Now, presumably, the first thing we're going to need

to start with is some cream?

Of course not!

No? We're not going to use cream? No. Cream is expensive.

It rots.

So, in substitution,

we're going to use reconstituted milk powder.

OK. Shall I put that in there? Yes, please. Right.

And whey protein.

OK, so we've put milk in the Foodamatic,

but, like the corn, it's broken the milk down into

its... I guess, a bit of fat and some carbs... Pour some in.

..but there's not much fat in the milk powder or in the whey protein.

No, but what did we take out at the end? Some corn oil.

Corn oil, right. Or sometimes palm oil is cheaper.

OK, so, instead of using animal fat or dairy fat,

we're going to use vegetable fat?

Yes. OK, so we've now got some extracted dairy stuff.

A bit of fat.

What else do we need? Add some sugar, presumably.

Exactly. If not, this will not be very tasty!

So we have high fructose corn syrup.

OK. Can you mix for me?

Yeah, I'll mix. High fructose corn syrup...

And this is going to be sweet like sugar,

but you said earlier it was a bit cheaper.

Way cheaper than sugar!

Hard to see this becoming delicious ice cream.

So the next thing it feels to me is strawberries.

We are going to need strawberries at some point

because we're making strawberry ice cream - that's the whole point.

So I'm going to make you say this

because it's a very complicated word.

So I'm proposing strawberries,

and you're proposing something called ethyl methylphenylglycidate.

Yes, in substitution of strawberries. Which smells...

APPLAUSE

I've been practising that all day!

A few drops. Just a few drops. Just a few drops.

Is this very expensive?

Er, not really.

Not compared to strawberries.

Not compared to strawberries. Seasonal, expensive.

It's non-seasonal. It won't go off... This is non-seasonal,

you just put it in. OK, so this is starting...

It's smelling of strawberries.

It's still looking... It's still looking pretty bad.

And it's separating - the oil is coming away from the other stuff.

Yes, which was one of the biggest problems of Zoe, right?

So we need something to bind it together. Yeah?

So, for that, we have diglycerides.

Diglycerides - an emulsifier to glue the fat

together with everything else.

And then... OK, so that's going to give it a sort of creaminess

in the mouth... A little mouthfeel. It's looking grey.

I mean, it looks absolutely disgusting.

Some colouring? We need a pink!

Yes! Bit of colouring. OK, let's add some pink... Put a bit of pink.

..colouring there. Stir that in.

And there's one final ingredient left here.

Xanthan gum.

Yeah. That will avoid the separation.

It will allow for it to be transported

without kind of slurping out.

So that will make our business successful.

We can then transport things.

It will help with that freezing temperature. Yes.

OK. It's like a bacterial slime.

OK.

So we've now got a pink-ish, er...

..mixture of various different stuff,

none of which I would really call food,

none of which we use in domestic cooking.

You're going to put that back in the Foodamatic. Back in my friend.

And out comes the finished product. Let's have a look.

After you.

OK, here we go.

Well, that... It's some very, very convincing looking ice cream.

Can I try? I'm going to try... It smells.

Smells of strawberries.

Do you want a little smell?

Here, Yanaina, get them to have a... Smell it.

Smells good. Smells good?

Can you hold it?

Is it cold?

No. No, it's not cold.

That's what I noticed.

Is this... This is not cold, is it?

So this is at room temperature

and, if I hold it like this, it doesn't flow out of the pot.

Yanaina, that is truly spectacular,

and you did it all without using any real ingredients.

No strawberries. No strawberries.

No ice. No ice.

No cream. No cream. Spectacular.

Yanaina, thank you very much indeed!

APPLAUSE

And I'm really sorry, Zoe,

you're...you're really not going to be able to...

Ahhhh!

..maintain pace in the modern... It's just business!

I don't know why you're all complaining

because what you all now have access to

is extremely cheap, fairly delicious ice cream

that you can buy at any time of the day or night

at the end of your road.

It works brilliantly well,

and, Yanaina, thank you very much for a fantastic demonstration.

Thank you!

APPLAUSE

So the food company that Yanaina and I have started

is now going to end up in an arms race

with lots of other food companies.

A bit like the arms race that we saw on our timeline.

Companies are going to have to compete with each other,

and there are two ways they need to compete.

They need to sell more food,

and they need to keep the price of those ingredients down.

And to help me understand a bit more

about how I might optimise my food company,

the one I'm running with Yanaina,

please welcome an academic philosopher.

He's the director for the Centre of the Study of the Senses at the

University of London and used to work with the food industry -

Professor Barry Smith!

APPLAUSE

Barry, I'm running this big food company now.

How am I going to get people to like my food products more?

Well, you don't just want them to like it.

The food companies really try to get people to want the food.

Now, I think most of us think that wanting and liking are...

I use the words interchangeably. Aren't they the same thing?

They're not the same. Wanting and liking sound like the same thing

when you're talking about food, but in fact they're different.

You like apples? I like apples.

But you don't want to keep eating them after you've had one.

Well, I'm a two apple a day guy.

I'm happy with that. And that's it.

And I don't think about them when I'm not eating.

But I think we all know the experience of having a plate

of greasy chips and, by the end, you don't really like them,

but you want to finish them.

That's wanting. That's what we're aiming for.

OK. It's a business - that's what I want people to do. Yeah.

How does this help?

OK, so how do companies get us to want the food more?

First thing, make it softer.

OK. So what we're going to do is talk about the food matrix.

Now, the food matrix is when our food like your apple

there has a structure.

Let's pour all of this in - exactly the same apple.

So you've got a lovely peeled, cored, juicy apple.

Now we're going to liquidise it.

Let's see what we can do. OK, here we go.

BLENDER WHIRS

You're pre-chewing your apple.

Is that a fair way of putting it?

That's exactly what I'm doing.

Let's see how we go.

I am going to pour out some of this sludgy stuff,

and you are going to eat your apple.

Now, I can consume much more quickly than you can.

You're still chewing.

I can just swallow the liquid.

So what that means is that I can get the sugars of the fruit

into me much faster. I can get the sugar hit.

Why is that good?

Well, that's good because I can go on eating this

because I get the quick hit -

I don't process it quickly enough, I'm still hungry.

I still want more.

Does this mean apple puree is bad for us?

No, but it does show us in that different form

that food processing has an effect on human physiology.

I can consume sugars faster.

I go on wanting them longer.

So processing, it's not necessarily good or bad,

but it does change the way our bodies interact with food.

That's exactly right. OK.

We're going to want to make soft food

that you can eat pretty quickly.

What other tricks might we want to do to sell more food?

We may want to make food drier.

People don't like dry food generally.

Why would we do that?

Well, most natural foods have got moisture in them,

and moisture is where the bugs are.

We can show you that because we've got two burgers.

On the right-hand side, we've got a home-made burger.

On the left side, we've got an industrially processed-made burger.

Now, let's see how they decay.

Look at the home-made burger.

So this is over several weeks, is it? Several weeks,

and it starts to decay.

The bacteria get in there through the moisture.

And you wouldn't want to eat that, would you?

This burger is... You'd almost still be willing to eat it.

But hold on. We've all eaten

industrially processed burgers before, and they don't taste dry.

They're not... They don't taste desiccated.

So, if we've taken the moisture out but we don't want them to taste dry,

we have to put in additives and emulsifiers

to give them the mouthfeel we like.

So there's an illusion of wetness? There's an illusion of wetness,

but we're also going to put in some salt, more sugars,

some more emulsifiers.

We're going to get it just to be so delicious.

OK, so the burger is still tasting wet and good,

but it lasts for a long time.

And then it seems like it's got a lot of energy left.

We haven't taken out any energy.

We've just taken out the water.

But you've compacted the energy.

These industrially processed burgers, without all that moisture,

they're energy dense.

What does that mean?

It means there's more calorie per mouthful.

And that, again, means you're eating too fast

to tell yourself that you're full,

that you should stop eating,

that you've had enough, but you're not going to slow down.

So we've got that system we've seen evolve on the timeline

that tells us you've had enough food now,

but, when we consume these new foods,

it's no longer able to say, you've had enough.

That's right. OK, that makes sense.

Now, what if Yanaina and I want to really go global

and start using cheaper ingredients and selling...?

Making more money, basically.

So we want to think of a product which is very cheap to make,

has cheap ingredients.

Ready made ingredients.

So, let's try a drink.

We want the cheapest, the most available

ingredient that goes into a drink.

What would it be?

Water.

Water.

Exactly right.

So, Chris, to make the water more desirable,

we're going to put in the equivalent of seven heaped spoonfuls of sugar.

So that is around three times more

than I would add to a cup of tea or coffee of this size.

That feels like... Three or four times? What's up with you?!

It adds... It's way...

I'm going to try this.

It's way too sweet. It's way too sweet.

This isn't going to work. No-one's going to buy this.

OK. So you know it's too sweet

and that's going to stop you from drinking it.

So we'll fix that because we'll add some sourness.

So here are some citric acid crystals.

Try that. OK.

And lots of these drinks do have acids in them. They absolutely do.

It's become a little bit more refreshing. Good.

I'm not going to say it's nice.

It's fine. It's now drinkable, but I'm not going to buy this.

You're not going to buy it because it doesn't yet have a flavour.

So I'm going to add this flavourant to it,

and you tell me what that flavour is.

OK, give it a stir.

Who wants to smell...

Great! ..the drink? Great! OK, tell us what you smell.

Orange. Orange.

The orange has it. But it's citrusy, isn't it?

I'm getting kind of... I'm getting quite a specific tangerine.

It's tangy, right?

OK. It's tangy. It doesn't look great.

It doesn't look like an orange drink. Right?

You wouldn't think that was a great orange drink,

so let's give it some colour.

So here's a nice food dye I can add.

Et voila!

And is this ready...?

It's now not bad.

It's refreshing.

It's got a little sourness.

I believe there's some orange in there.

It smells of orange.

Doesn't feel like this is... I'm not sure I'd buy this.

So let's jazz it up a little bit.

What I'm now going to do is I'm going to put some CO2 in here.

I'm going to make it fizzy.

So what does the CO2 do,

apart from wet the desk?

It suppresses the sweetness and accentuates the sourness.

That's going to make it possible

to have those seven heaped spoonfuls of sugar and find it palatable.

Try that. Mm!

And now it's become quite an exciting product.

Is it ready for market? Can we put it on the shelves?

Well, I think we have to decide how we're going to deliver it

and, for that, we probably want to put it in a can,

but we also want to make it really cold.

Now, we'll put it in a can,

and we'll probably get people to be excited

about what they're going to buy

by putting a nice big orange on the front of the can.

Was the orange flavour from an orange?

Er, no.

But if you look at the small letters,

it says "orange flavour".

So is that allowed? We can... We can get away with that?

We can. If you say so! We can. OK, great.

So now people I think are going to believe...

They're probably not going to read that word, "flavoured".

It feels to me the interesting thing about what you've done is

I've forgotten how much sugar there is in this.

Absolutely. You're smuggling it into me.

Yeah. So I'm bypassing the natural system that you all have to say,

"That's too sweet,"

because I've used all sorts of tricks to make it possible

for you to ingest that sugar.

More sugar than you would usually take.

But why do I want to give my customers

that massive dose of sugar?

Why not just make it a bit less sweet in the first place?

Because if you like drinking it like that,

and you get that big sugar rush,

you start craving that and you'll go back for more.

Now, I also want to give you another clue

about what's going to come next - it's that lovely fizzy drink,

and that's the sound of the can opening.

CAN CLICKS AND HISSES OPEN

And that's the noise that we hear...

The faces! I can see people going...

Yeah? You know that noise, right?

And what usually follows that is, it's a big lug

and then an "ahhh".

My mouth is salivating. I'm ready to go.

I've given you two cues.

I've given you the orange cue and then the sound of the fizzy drink,

and your brain's expecting something.

You've just had it

and, when you get what you expect, the brain is very happy.

Barry, thank you very much indeed for sharing all this. Pleasure.

Brilliant. Professor Barry Smith.

Now, what Barry has just done is to ultra-process that water.

And this is a term - have you heard the term ultra-processed food?

Right. There has been some debate around ultra-processed food.

Many experts in the UK, including me,

agree that the main harms from our diet, of which there are many,

they come from the fact that we now eat too much

industrially processed food products that are typically high in energy,

high in saturated fat, high in sugar and high in salt.

And the best scientific evidence shows that, if you eat a diet

high in these kind of foods,

then it causes health problems.

The most obvious is weight gain,

but there are lots of other links to physical

and mental health problems too.

Now, there's lots we still don't understand

about ultra-processed food, and I think what's really important to say

here is that not all ultra-processed food is equally harmful.

There's products like that ice cream, confectionery, crisps,

lots of snacks, that is obviously harmful.

We've known it's harmful for a long time.

But then there are products like fishfingers, lots of types

of baked beans, supermarket bread.

These are products - they're ultra-processed, for the most part,

I eat them myself.

I feed them to my kids.

The thing to remember, though, is that, whilst it's not

all equally harmful,

it is almost all high in calories,

saturated fat, salt and or sugar.

There's very little ultra-processed food

that we can say is truly healthy.

And I would argue that products like that

are not the foundation of a healthy diet.

You might now all be expecting me to tell you what to eat,

and I'm not going to do that.

The reason I don't tell people what to eat

is because, for lots of people in this country,

ultra-processed food is the only available affordable food.

So what I'm interested in

is what the science tells us about how to change the food environment

so that healthy food is more affordable, more available,

and you can all make more informed, true decisions

about the food that you buy and eat.

So I want to hear from you,

and some of you have sent in pre-prepared questions.

The first question is from Marley.

Hi, Marley.

Do you want to read out your question?

If you had to create the ultimate superhero snack

that's good for the planet and makes you feel awesome,

what would be in it?

Marley, I don't have to create that snack.

Those snacks already exist.

Um... Bananas, carrots, nuts, a glass of milk.

These are all really good, healthy snacks.

They're part of what we call whole foods or minimally processed foods.

But, Marley, a brilliant first question.

Thank you very much.

APPLAUSE

OK, Sheila. We've got a question from Sheila.

Hi, Sheila. Is there any food that's never healthy to eat?

There's a lot of stuff in the world

that we think of as being pretty harmful,

but, if you only do it once in a while,

it doesn't do you any harm at all.

If you have a can of cola once every couple of weeks,

it doesn't do your body very much harm, we wouldn't worry about that.

The problem is that, as Barry explained,

many of these food products are engineered

so that you want them more often than once a week -

in fact, you have them on a Monday morning,

and then by Monday midday you want them again,

and Monday evening, so that for me is the difficulty.

We talk about things being fine in moderation,

but that puts a burden on all of you

in the face of foods that have often been engineered

by very, very sophisticated teams of scientists,

and marketing teams, and these foods are put in your eyeline

so they're very hard to avoid.

So, in general, I would say, if you can be moderate,

there are no really terrible things you should never eat,

but that is very, very hard for a lot of people

and it's hard to be moderate.

Sheila, a brilliant question.

Next we've got Isaac. Where's Isaac?

Is it possible to feed the whole world without ultra-processed foods?

So, this, Isaac, is at the core of the discussion.

We've seen the massive efficiencies of the industrial food system.

There's no question it produces food that's very cheap and abundant,

but it isn't sustainable.

We throw away about 30% of the food, OK?

Of all the food we produce.

So the system is incredibly wasteful.

It is the leading cause of plastic pollution.

It is the leading cause of loss of biodiversity.

It is the leading cause of deforestation.

OK?

The reason we cut down tropical forest is to grow food,

and we feed most of that food to animals.

OK? So we need a very, very different food system.

And the way we start, in my opinion, is with demand.

And that is what these lectures are about.

I'm not going to tell you what to eat

but, at the end of these lectures,

you might demand slightly different food -

in your schools, from your shops.

The food industry is incredibly smart and dynamic,

and they will be able to adapt

and produce different food in a different way.

Now, over the course of these three lectures, we have barely scraped

the surface of the food system,

and I want to end by throwing the problem and the solutions

open to all of you.

You're going to become farmers, scientists, chefs,

parents, teachers - all people who deeply, deeply care about food.

Together, I think we can rediscover

the complexity and the diversity of human diet, of human food.

And we will and can find new ways,

and redevelop old ways,

of feeding everyone affordably

and ways that support the flourishing of all the other life

on Earth that we depend on.

Thank you all very much for listening.

CHEERING AND APPLAUSE