We are all apes.
All of you are apes. Every single one of you.
If we look in the animal kingdom,
our closest living relatives are chimpanzees,
bonobos, and gorillas.
So, here's one of my cousins.
We look very different.
So, when did our family trees split apart from each other?
What makes him a gorilla?
What makes me a human?
This is Albert the gorilla. I'm Professor Alice Roberts.
Welcome to the second of this year's
Royal Institution Christmas Lectures.
Now, Albert is going to come and say hello to some of you.
He's very interested in you.
I'm sure you're interested in him as well.
On the surface, he looks really different, but maybe
when you get a bit closer, you can see some similarities.
If you hold up your hand, so...
He's looking right at...
He's looking right at you there, in the hoodie.
If you hold up your hand, he should hold up his hand as well,
and you can compare your hand to his. You can see that his hand
is very large, but he's got four fingers and a thumb.
He's got fingernails.
Try smiling at him, show your teeth.
He'll recognise that as a smile, he knows that you're
being submissive. He's baring his teeth as well.
I think he quite likes you. Do you want to say hello?
Hi. LAUGHTER
It's all right, he's harmless.
He does like you! Awww!
He's found a friend - a cousin and a friend.
Albert, come back down here, though.
Come on. Come down.
Albert is a great ape.
We are part of this family of great apes as well.
And so those great apes include gorillas and chimpanzees
and bonobos and orangutans.
And then our family of great apes is part of an even bigger group
of animals called primates,
and all primates have various things in common.
So... SHE LAUGHS
We're all very good with our hands. We've got grasping hands.
All primates have clavicles. You've got collarbones,
haven't you? That's one thing that makes you a primate.
And also, all primates are really, really good at climbing.
ATMOSPHERIC MUSIC PLAYS
Alex and Dane, that was absolutely amazing!
How wonderful to see people who can use their bodies in that way,
and move around in 3-D space like that.
It reminds us just how flexible the human body really is.
I think a lot of us move around in a really boring way
in comparison.
Which one of you here has ever tried to climb a climbing frame or a tree?
You've all done it.
So we are primates at heart.
Thank you very much.
And Alex and Dane, what an amazing performance.
I thought you were absolutely brilliant.
Let's ask Albert what he thinks, though. What do you think, Albert,
for their parkour performance?
Awww!
Oh, I think it was better than that.
Oh, well. A big round of applause for our great apes.
APPLAUSE
Alex and Dane showed us brilliantly how we can still move around
in 3-D space as primates do, if we want to, and if we train at it.
But in fact there are other clues to our primate connections,
and there's one clue I'd like to show you now,
which is only there for a fleeting moment in our lives
when we're very, very young.
So, I'd like you to do a very gentle round of applause now
for Vicki and Aria.
Hello, Vicki. Hello. Hello, Aria.
So, Aria is very, very small. She's a very new person.
How old is she? She's six weeks. She's six weeks? Yes.
You're gorgeous! Aren't you lovely?
Now, Aria is so small that she still has a reflex
that all of you will have lost long ago,
but I might be able to show it to you.
I want to look at her hand, is this all right with you? Yes, of course.
And what I'm trying to do is put my finger in her hand,
and she closes her fingers... ARIA MOANS
She doesn't like it. Oh, no, Aria!
I'm sorry, poppet! Oh, oh. It's OK.
She's really gripping my finger, really strongly.
She's got this incredible reflex which is elicited,
I'm making it happen just by slightly tickling the palm
of her hand, and she grabs on.
ARIA CRIES Aw, baby! Good girl.
So, this reflex disappears by about six weeks of age,
but it's something that we think is left over
from our ancient primate ancestors.
And, Vicki and Aria, I've got a little video here...
..to show you some cousins. So, these are chimpanzees.
And what you can see here is the chimpanzee baby
on its mother's back,
and you can see how the mum's moving pretty swiftly,
and that chimp baby, even though it's tiny, has to cling on
for dear life, so it's really gripping with its hands.
So this is where we think this grasp reflex is
left over from in our babies.
But by about six months, she'll have forgotten how to do it.
Thank you so much, Vicki. Thank you. Thank you, Aria.
Thanks. Another gentle round of applause. Thank you!
So, we've seen now evidence of primate connections in the way
that we CAN move with our bodies, if we want to.
We've seen primate connections and this amazing grasp reflex
that we're all born with but then we then lose,
and there are other signs of these connections
when we look at anatomy.
I'm an anatomist, so I go under the skin and I start looking
at the structure of the body,
and what I've got here are two bones from two different species.
One of them is from a human, and one of them is from a chimpanzee.
First of all, there's this very, very narrow groove at the top
of this bone. If we look at the bottoms of the bones,
there are some differences as well.
So both of these bones have got a ball shape at the bottom.
And on this bone, you can see that there's a much more prominent
lip on it. So, there are really subtle differences that tell me
that this bone is the chimpanzee humerus, and this one
is the human humerus, but they're kind of shockingly similar.
Now, we're going to put them in context and bring in two complete
skeletons - a human skeleton and a chimpanzee skeleton.
And when you look at a whole skeleton like this,
I think you notice the differences more than the similarities at first,
especially because the human has been hung like this, so he looks
like he's walking on two feet.
And the chimpanzee's arranged like this, so he looks
like he's just getting ready to go knuckle walking,
which is what chimpanzees tend to do when they drop down to the ground.
So that was the humerus that we were looking at
in both of these animals.
That's a very similar bone in the chimp and the human.
There are other bones which are much more different.
So, if you look at the pelvis here, that's a completely different shape.
It's got a very long, flat blade,
whereas our pelvis is kind of a basin shape, and it's adapted to
us walking upright on two legs.
But there are other bits that are quite similar still,
and our hands are a great example of that.
So, if I hold up the chimp hand and the human hand,
you can see that the chimp thumb is a bit weedy
compared to the human thumb.
But still both of those hands are capable of doing something
that you can all do.
Those thumbs can move in a very special way.
The thumb can move right across the palm,
and you can touch the tip of your thumb to your little finger.
It may not feel like a really special thing to be able to do,
but this opposable thumb is really important in grasping.
It's something that other primates have as well,
but our opposable thumbs are exceptional.
So, they're really great when you're making and using tools.
But I want to demonstrate just how useful they are with two volunteers.
So, can I have two volunteers from the audience, please?
So, I'd like you in the mustard jumper and...
..yes, in the grey hoodie. Come down, come down.
And we've got a little challenge for you.
As you can see, it involves grapes. What's your name? Esme.
Esme, so, you're over there with the green grapes, Esme.
Are you right or left-handed? I'm right-handed.
OK, can you put your left hand behind your back? Sure.
Lovely. And what's your name? Lehner. Lehner.
So, Esme and Lehner, you're going to be pitted against each other
in a grape-picking challenge.
You're both right-handed, so, Lehner, if you put your left hand
behind your back as well, so you're not tempted to use it at all.
What I want you to do, when I say go, is pluck grapes from that bunch,
just using one hand, and put the grapes in this empty bowl.
So, that's the challenge. All right?
So, taking, taking grapes... I'll put the bowls round that way
for you as well, so it might be a bit easier.
So, you pluck the grapes off, you put them in the bowl
and you've got 15 seconds to do it.
I'm going to give you a countdown.
One, two, three, four, I declare...
..a thumb war. Go!
15 seconds.
Who's going to do better at this? LAUGHTER
I think that might be cheating! LAUGHTER
Right, stop! Stop, stop, stop! Drop the grapes.
Now, the really amazing thing about this demonstration
is it's meant to show how, if you don't have your opposable thumb...
LAUGHTER
I was just taking it up...! ..you're much worse at plucking grapes!
Do you know what, Lehner? We've done it with so many people
this afternoon in rehearsals, and we always end up with a
great pile of grapes over here and a very small pile of grapes over here.
LAUGHTER
I think possibly you cheated by picking up the bunch and shaking it.
Maybe. LAUGHTER
But this does show something really important.
So, if you don't pick up the bunch and shake it,
then you're going to end up with fewer grapes in here.
Humans are also rather ingenious and very good at problem-solving.
So, thank you very much to Lehner and Esme
for testing out their thumbs. Thank you.
So, lots of things, then, that we've got in common
with our primate cousins - anatomy, behaviour -
but actually the similarities go down to the level
of molecules inside yourselves.
You can actually look for similarities like this
when you get down to the level of DNA.
So, this is when I'd like to introduce my friend,
the geneticist, Professor Aoife McLysaght.
APPLAUSE
OK, thank you so much.
Well, one of the really useful things about genetics and DNA
analysis is that we can actually put a number on these similarities
that Alice has already been describing.
So, the people in row five all have a very special ribbon
in front of you, all around there.
So, could you just take hold of that ribbon?
I'm going to tell you to stand up. So, are you ready?
OK, can you stand up, please?
And we're going to show this ribbon to everybody.
OK, great. So, what you can see here across the room,
that's a DNA sequence.
And that's not just any old DNA sequence, that's real DNA sequence.
The top ribbon is showing you DNA sequence from the human genome,
and the bottom ribbon is DNA sequence from the chimpanzee genome.
It's a real sequence.
This actually comes from a gene called Factor IX, which makes
part of your blood clotting system.
So the first thing you might notice when you look at these
is that the top and the bottom are mostly the same,
and this is what we see - the human and the chimpanzee
DNA sequences are really, really similar,
but there are a few differences. So I would like the people
in row four to help me out here. If you could just have a look,
and I just want to see letter differences.
So, raise your hand and show me if you've got one.
So, yeah, we've got one up here. Thank you.
So, what we see here is, in the human sequence on the top, we have a
C and a G, and in the chimpanzee sequence on the bottom,
we've got a T and an A, so we've got two letter differences there.
Have we got somewhere else? Got a difference? Give me a wave.
Yeah, over there.
So, yeah, so this one here, just one letter
that's different here. So, we've got a T in human and a C in chimpanzee,
but the rest, they're all pretty much the same.
So, that's just one kind of difference that we can look at.
And if we looked over the whole genome, we find that this amount
of difference is actually quite representative of what we see
over the whole DNA comparison.
So, that's about 1% different, or 99% the same,
you could say. But that's just one way of counting the differences.
There are actually other kind of differences.
So, somewhere in this ribbon, we've got a loop that's
sticking out. Give me a wave if you can see the loop.
OK, over here, yeah.
So, in this loop here, that's the human sequence
going across the top. Chimpanzee sequence across the bottom.
And there's this bit that's looping out in human,
there's nothing to match it against on the other side.
So this is...there's a piece of DNA that's either been inserted
into the human genome or deleted from the chimpanzee genome.
But we just, we can't match those up.
And there are other bits like that around the genome,
if we were to do the whole comparison,
and that adds about another 3% different.
So, if we put these together, we get it to about 4% different,
or 96% the same.
It's the kind of thing you might like to see on a T-shirt
or something, don't you think? Alice, I'd like it on a T-shirt.
ALICE LAUGHS
OK. OK, then. Yeah.
We'd better do a countdown, hadn't we?
OK, yeah, we should do a countdown for this. Three, two, one!
Boom! Woo! LAUGHTER
OK, so, thank you so much.
So, the people in row five can sit down.
Who got the T-shirts? Can we have a look at them?
"99% chimp," yeah, great.
What does your one say?
"96% chimp, including insertions and deletions."
Very good! Who's going to wear those T-shirts?
Yeah? Wear them with pride. 96% chimp and proud.
We made that comparison kind of easy for you.
We just showed it to you.
Now I'm actually going to test you on something
we're not telling you in advance.
So, we've got some other species we want to compare.
So, what we have here...
So, Alice has a human and a chimpanzee,
and I have a mouse and a rat.
They're very cute, aren't they? They're very sweet. Yes.
So, I'm going to ask you to tell me which pair you think is more similar
at the genetic level.
So, hands up if you think that human and chimpanzee are most similar
at the genetic level.
So, good few hands.
Hands up who thinks mouse and rat are most similar
at the genetic level.
Oh, not as many, OK. This is interesting.
So, even though mouse and rat look much more similar,
they're actually very similar-looking
- at least they are to me - they are much more different genetically
than human and chimpanzee are.
So, we have 99%, or 96 taking into consideration the insertions
and deletions, but in rat and mouse, when we compare them,
just the genes we can align, it's about 93%.
And then there's lots and lots of those loops.
So, lots more that we can't compare.
These animals look very, very similar.
I mean, you've got DNA here making a very similar body -
little ears, little paws, little tail.
These animals look much, much more different from each other,
so that small percentage difference translates into a big difference
in actual body. A huge difference, a huge difference. Yeah.
But what we've done now, anyway, is we've learned how to count
those differences and describe those differences, but the thing
we really want to know is how the genetic differences
make those physical differences that you see.
Because, despite the similarities, there are these big differences,
aren't there? There's a big gulf between us and our closest
relatives. I mean, chimpanzees don't go to school.
Chimpanzees don't go to Christmas lectures.
And I don't think Father Christmas even knows that chimpanzees exist.
Very sad indeed.
There's another big difference, and that's when chimpanzees
stop climbing around in trees and come down to the ground,
they don't do what we tend to do, which is walking on our two feet.
They tend to walk on all fours.
They knuckle-walk.
So, when did we start walking on two feet?
In order to answer that, I'm going to need a very brave volunteer,
and somebody who's brilliant at balancing.
Er, Christmas jumper in the second row back, please come down.
That's a fantastic jumper!
Thank you very much for volunteering, you're very brave.
What's your name? Stephen.
Stephen, right.
Now, Stephen, you can see exactly what you volunteered for.
So, this is a tightrope challenge.
So, I'd like you to go and stand on there.
I'll help you get up.
And before you start doing this tightrope challenge,
let me just show you what I want you to start doing, because I'd like
you to behave a little bit like one of your primate cousins.
making its way across a tightrope. LAUGHTER
So Stephen, what I'd like you to do is bring your hands down to
the cable here, bring your hands down to the tightrope.
Can you go across on all fours?
Are you going to be able to make it?
Is he going to be able to do it, ladies and gentlemen?
No! I'm sorry, Stephen. I don't think anybody in the audience
could do it either. I don't think you can do it.
There's plenty of people that are keen.
We've tried it with lots of people. Nobody can do it.
Nobody can get all the way from there to there.
We are apes.
We've got quite big bodies compared with the capuchin monkey
that you just saw.
He's a little, tiny small-bodied monkey.
He can run along, he can keep his body weight
above quite a narrow branch, or even a tightrope.
How would you prefer to travel across that?
Standing on two legs with weights on my either side.
OK, I'm not going to give you weights, but if you pop back
up there, shall I give you a hand, you all right?
Yeah, I'm good. You can do it on two feet, then.
Have a go then, let's be nice and quiet, let's give him some...
That's it! Yeah. Try that.
I'm going to let you go now, Stephen.
You all right?
LAUGHTER
It's really difficult.
It's really difficult, and it's also quite terrifying,
even though you're only a foot or two above the ground.
I'm going to do something now which I think will make it
an awful lot easier for you. So, you see that rope going up?
So if you walk underneath that rope, and back up on the pedestal,
now you can use this to help you.
Don't pull on it hard, and just use one hand.
But I think it will give you a lot of help.
So, let's see how Stephen does this time.
He's using the rope just to help him balance,
he's not putting much weight on it at all, you can see.
He's weight-bearing on his feet.
Well done! Well done!
Stephen, that was absolutely brilliant.
And I now want to show you an ape doing something very similar,
shot from a slightly strange angle, I must say.
But let's have a look at an orangutan doing the same thing.
So, what that orang is doing is walking along that rope
on his feet like you walked along the tightrope,
and using his hands to stabilise him.
So, you were doing exactly the same thing.
Thank you very much. Thank you.
We can do this thing of walking along a tightrope and
suspending ourselves, or at least stabilising ourselves,
by holding on to other things.
And as we've seen with the orangutan,
other apes do this as well.
So, what we think happened deep back in our ancestry...
Oh, hello.
What we think happened deep back in our ancestry is that our ancient
tree-living ancestors were doing this, were walking around in trees,
and then when they started walking on the ground more,
it was quite a simple thing for them to do,
to drop out of the tree and just continue walking
on two legs, on two feet, on the ground.
So we don't have to explain how you go from being a four-legged
quadrupedal animal to being an upright animal.
We think our ancestors always were upright,
and then they just swapped walking in the trees
for walking on the ground.
And then, by the time we get to about four,
to three million years ago, we find ancestors who have started to adapt
in their bodies to this new way of getting around.
So, their skeletons have started to change,
so they're getting better and better at walking.
And I want to introduce you to one of these ancestors.
So this is a reconstruction of the fossil of a very,
very famous fossil discovery.
She's called Lucy, and she was discovered in Ethiopia.
She belongs to a species called Australopithecus afarensis.
Australopithecus means southern ape,
and afarensis means she comes from the Afar region of Ethiopia.
And this is a reconstruction of Lucy here, so we can imagine
what she would have looked like in the flesh.
So we can see from her skeleton that she's got adaptations
to walking on two legs.
Her pelvis has changed, it's become adapted to bipedalism,
to two-legged walking.
Her femur, her thigh bone, is curving in to bring her knees
and her feet underneath her centre of mass.
She's still got some adaptations to climbing
left in her skeleton, though, including quite curved finger bones.
And we're not quite sure if she was still doing
a lot of climbing,
or whether these are just left over from HER ancestors.
But she's quite small.
There are some other individuals from her species who are a bit
bigger than her. But there's something else that's
quite striking, I think, about her limb proportions.
She's got longish arms and short legs,
so she doesn't really look like us yet.
And there's a change to long legs that happens about
two million years ago, with a new species appearing.
And this species is called Homo erectus.
And Homo erectus appears about two million years ago.
This particular reconstruction is based on a fossil
from 1.5 million years ago, and he's called Nariokotome Boy,
because his fossilised remains were found
near the Nariokotome River in Kenya.
And he's quite interesting when you look at his bones,
because he looks like he's 15.
Have we got any 15-year-olds in the audience tonight?
If I were to do an X-ray and look at your bones, I'd see that
some of your bones would still have gaps at the ends.
They haven't fused yet, cos you're still growing.
And his skeleton looks a bit like that,
but you're nearly fully grown.
So he's got the skeleton of a 15-year-old, almost fully grown,
but then if we look carefully at his bones and his teeth,
it turns out that he was only 8.
So he's only 8, but with the body of a 15-year-old.
He grew up really, really fast.
He didn't have the long childhoods that we have,
and those childhoods are really important.
Important to us as humans.
They allow us time to learn before we grow up into adults.
We can see other things in his skeleton.
In his back here, he's got strong back muscles,
and then moving down to his legs, he's got strong leg muscles,
and he's got really springy tendons, particularly this one here,
the Achilles tendon, that attaches at the heel.
We can see from the bones that he had a really lovely
big springy Achilles tendon, and that's why we've reconstructed
him like this, because we think Nariokotome Boy was a runner.
But in order to see just how good the human body is at running,
we're going to look at it in action, and Aoife's in the library
with a runner.
Hi, Alice. Yeah, I'm here in the library, and I'm with Marcus
from Sheffield Hallam University, and also our very wonderful
volunteer Tom who's been running
here on the treadmill for quite a few minutes.
So, Marcus, you've been capturing his movements.
Yeah, exactly. So, you might see that Tom's covered
in all of these spherical markers,
and what we can do is use these motion capture cameras
that you can see dotted around in the red cameras, and they can
really accurately measure the position of those markers.
Yeah, and we see his head is staying quite steady,
and we also see that his shoulders are moving back and forth.
So motion capture is a technology which people like Marcus
who are sport scientists can use to analyse how the human body moves,
but also to help athletes improve their performance.
And we can see, looking at that little stick man
there of Tom, his shoulders are moving.
So by the point in time we've got Nariokotome Boy,
we've got a nice long waist, and that enables your shoulders
to rotate, and that helps you to balance and it makes
running more efficient.
And we've also got his head staying quite still,
so, like Nariokotome Boy, he's got nice strong muscles
and that strong ligament in the back of the head, and strong back muscles
to stop his body pitching forward.
Cos actually when you're running, you're pretty much falling over
almost at every step, and you've got to stop yourself doing that.
So we're seeing those adaptations in action.
But actually, there's something else that would stop you in your tracks
with running, and I think, Aoife, you're measuring that as well.
Yeah, so Tom is a pretty wonderful volunteer because he's also
swallowed one of these.
This is a really small thermometer.
And he was asked to do this by Dr Danny Longman
from Cambridge University, who's also joining us here.
So what have you been measuring?
Sure, so the pill that Tom swallowed earlier is transmitting data
wirelessly to this laptop here.
And that's giving us information about Tom's deep core
body temperature, letting us know how warm he really is.
And what do you see here? So, we've got a graph of his temperature?
We do indeed.
So, we see here at rest, Tom had a core body temperature of
37 degrees, which is that of a healthy human.
However, when he started to run about here,
we see that his core body temperature started to rise,
and that was because his muscles were activated and muscle activation
generates a lot of heat.
He looks quite hot! He does indeed.
So, when Tom started to warm up, his evolved heat loss mechanisms
began to kick in, and he was able to lose heat at the same rate
as his muscles were producing them.
And we can see here we actually get a plateau in core body temperature.
And is this the same, then, for other animals?
Well, if we were to have a gazelle or a cheetah doing this experiment
in place of Tom, we would see that the core body temperature
would continue to increase.
They don't have the mechanisms to lose heat that we do.
So a cheetah would have to stop, despite being so fast?
Absolutely. Yeah, yeah. So Tom here is better than a tom cat!
So there's obviously something that our bodies are doing in order
to regulate that temperature and to try to keep us cool
whilst everything we're doing is trying to make us hotter
and hotter and hotter.
And the amazing thing about being able to regulate our
temperature like this is it means we can just carry on running.
We're really good at endurance running.
We can even outrun horses and dogs, and there's a particular secret
to how we do it. That was good, wasn't it?
And, Aoife, you happen to be back in the theatre. Uh-huh.
So, you're going to demonstrate for me, Aoife... Yeah.
..what our superpower is, how we manage to keep our temperature down.
OK, yeah. There's a spike. Uh-huh. And we've got these balloons.
So this balloon represents the amount of sweat that a 70kg dog
sweats out during an hour of exercise.
70kg is bigger than me. Yeah. That's a big dog. Yeah.
I'm going to go and stand over here. OK.
You're making me worried, Alice.
I'm wearing my good shoes!
OK. Well, I need a countdown.
I'm not doing this by myself, OK?
Three, two, one...
OK!
It wasn't as bad as I expected, so that's a 70kg...
That was a 70kg dog.
Dogs don't sweat that much.
They have to stop, and they have to bring their temperature down
by panting. OK. But humans sweat quite a bit.
So this balloon contains the amount of sweat that a human sweats out
during an hour of exercise.
So, we probably need a countdown again.
Three, two, one...
AOIFE SCREAMS
That was two litres! Oh, yeah!
Two litres of sweat. I think I felt it, yeah.
Are you a bit wet? I'm a bit wet!
I'm sorry, Aoife. You're not really sorry though, are you?
Not really, no. Not really.
So, Aoife has magnificently... I'm so sorry, Aoife.
She's going to get me back now in lecture three, isn't she?
She's going to be thinking of something to do to me.
Aoife's demonstrated - brilliantly, I thought, absolutely brilliantly -
the secret of sweat.
This is how we humans manage to keep our temperature down,
and there's something about us that's very,
very different from our closest living ape relatives,
and that is it looks as though we've lost the fur over our bodies.
In fact, that's not quite true, because over the surface
of the human body, we've got five million hair follicles,
and that's actually the same as a chimpanzee has.
It's just that our hairs are so much finer over our bodies,
and that's really important,
because it means those hairs don't trap sweat.
The sweat spreads out on the surface of the skin,
and then it can evaporate off, and as it evaporates off,
it takes heat with it.
So we're really, really good at sweating.
And so we are able to run long distances, and we think
this was incredibly important to our ancient ancestors,
people like Nariokotome Boy.
So going back two million years ago,
we've got the expansion of grasslands in Africa, Savannah.
And with the expansion of those grasslands, we've got
the expansion of populations of animals who are eating that grass,
so grazers. And then the predators are eating the grazers.
And if you could run fast, and get to a carcass that a predator
had taken down, perhaps those lions have gone off to sleep in the shade,
you can steal some of that meat.
So our ancestors were certainly scavenging,
they may have been hunting as well, and we also know that they were
making stone tools that can cut through flesh and sinew.
And now I want to introduce to you two people who make stone tools
today, and they make stone tools that are very much
like those of our ancestors -
Antony and Nada from the Ancient Technology Centre in Dorset.
Let's give them a round of applause.
Now, before they get started, some very sharp flakes can fly
from this, so I'm going to put goggles on,
and those of you in the front row have got goggles.
I think, yeah, front and second row.
We may get some flakes flying off, so let's just be careful about it.
So, Antony and Nada are going to start making stone tools,
and they do it by bashing rocks together.
It's actually quite complicated, isn't it? I've had a go
at doing it, and it IS difficult to do it.
There's quite a lot to it, yeah, it's quite a technical process.
Bash a couple of flakes off, and let's see what happens. OK.
And he's using a cobble to break those flakes off.
That's quite a big one. That's amazing, look at that.
As soon as you do this, as soon as you start breaking flakes off,
you end up with things that have got very sharp edges.
It's a cutting edge. I mean, this is a stone knife.
Absolutely brilliant.
So, you can actually see how thin that flake is just there,
especially if I shine a light through it.
You should be able to see quite nicely
that it's incredibly thin at the edges.
That's a really, really sharp cutting edge,
so you'd be able to cut up your Christmas turkey
with that very easily indeed.
Thank you.
So, Antony's making fairly basic flake tools,
and over here, Nada is making something a little bit
more sophisticated.
The kind of tool that Nariokotome Boy might have made, actually.
Nada, would you mind holding it up? Not at all.
So, this is a hand axe. She's making flakes which are useful as knives,
but this is useful too, isn't it?
Yes, absolutely. It's a multipurpose tool.
Yeah, so you could use it for chopping, maybe,
smashing bones to get marrow out of.
Absolutely, yes. Yeah, all sorts of things.
The other really interesting thing about this particular shape
is it's a shape that gets copied and copied and copied,
and passed on down through the generations.
And I think this tells us something really important about the minds
of these toolmakers, because it's not just simply
a question of bashing away at it, is it?
You've got a shape in your mind.
No, you have to visualise what you want to get out of a rock,
and work towards that shape, absolutely.
Yeah. So you are like a sculptor, you're making the shape.
So that means our ancestors, even as long ago as Nariokotome Boy,
were capable of abstract thought like this.
They could hold the idea of a shape in their heads.
It's quite a special thing to be able to do.
And not only that, they could make it real,
which is even more special.
Thank you ever so much, Nada and Antony.
That was brilliant. Thank you.
Now, stone tools tend to stick around in the archaeological record.
They're the kinds of things that archaeologists can easily find
and dig up.
They are, after all, stone. It doesn't really rot away.
Things we don't find so often in archaeology
are made of organic materials.
So, anything made out of leaves or grass or wood
is usually going to rot away.
And so it's very difficult to know exactly what our ancestors
were using in terms of wooden tools at this point in time,
but we do know that lots of hunter gatherers use very simple
wooden tools like this.
And you can imagine making this, just taking a stick, and then using
one of those stone flakes to sharpen the end of it until you get a point.
And then perhaps what you're thinking is
I'm going to use that as a spear.
Well, I could, but actually you can use it for something else
as well. Something very important.
Lots of modern day hunter gatherers use sticks like this to dig food
out of the ground.
And there's a really important clue as to what that underground food
might be when we delve into genetics.
That sounds like my part!
Yeah, so we can actually learn something very interesting
about our adaptations by looking at our genes.
So, in your mouth you have spit, of course, and in your saliva,
there is an enzyme called amylase that helps you digest starch
in your mouth, start breaking down the starch in your mouth.
And the amount of amylase you have in your saliva
depends on your genes.
So, all of you will have noticed you have a little packet
of crackers, so you can get your packet of crackers out.
Yeah, so you're not to start eating them yet, because I need to
tell you what to do first, but you can just quickly
take them out of the wrapper.
OK, what I want you to do is I want you to start chewing the cracker,
but you're not to swallow it, OK?
You have to keep it in your mouth and keep chewing.
Not yet, not yet.
It's going to get all mushy, and it's going to go all gooey
and whatever, but that's fine.
Just keep it in your mouth and keep chewing, chewing, chewing.
And at some point, the flavour is going to change,
so when the flavour changes, I want you to stand up.
OK, so is everybody ready? Steady? Go.
Just chew, chew, chew.
Don't swallow it.
And then let me know when the flavour changes.
We've got one already, very good.
Yeah.
More. And this is totally normal.
It's actually expected that different people stand up
at different times.
This is amazing, everybody's starting to stand up! So...
I'm running around the stairs...
What was the flavour change for you?
Boring. Boring! OK.
It changed to boring. did it start out interesting?
What did you think? Sweet.
It changed to sweet. What did you think? Sweet.
Interesting. This is very good.
What did you think?
It got sweeter. It got sweeter.
It's interesting that we have people saying sweet,
because that's what I expected.
So the amylase enzyme in your saliva, what it does
is it breaks the starch down into simple sugars.
So it's what we expect, is that it starts to feel sweet for you.
And the reason different people stood up at different times
is because actually we know that humans have different numbers
of copies of this gene that makes the amylase.
So, some people have two copies, but some people have as many as
18 copies of this gene.
So if you have more copies of the gene,
we expect that the flavour would change to sweet sooner.
And in parts of the world where there is a traditional diet
that's very starch rich, so things like rice and potatoes
and yams, we see that people who come from that part of the world
tend to have more copies of the amylase gene.
So it's an adaptation to diet that's written in our genes.
Yes, but our ancient ancestors also had another way of unlocking
the energy from their food.
By a million years ago, our ancestors had controlled fire.
And with fire, they could do all sorts of things.
They could obviously keep themselves warm,
they could ward off predators, and they could do something
really important when it came to food - they could cook it.
So things start to taste a bit nicer, perhaps.
But even more importantly, if you can cook food,
then it means you're doing some of the work in unlocking the energy
from that food before you get it anywhere near your mouth.
So you're effectively getting more energy from your food.
And we think that this is reflected in a change
in our ancestors' anatomy.
So, over time what happened is that our ancestors
- thank you very much - who started off with teeth
as big as this, huge gnashers, over time, those teeth diminished
in size, and got a lot more like the teeth in your mouth.
So modern human teeth are tiny in comparison
to this australopithecine jaw with its teeth.
So, if you can make your food softer - you can do that by pounding it,
you can do it by cooking it - it means there's no longer
any advantage in having great big teeth like this,
and your teeth can grow smaller.
And then something else that happens is that brains are getting larger.
And if I compare these two skulls by showing you the skulls like that,
you can see that this modern human skull is much bigger
compared with this one.
The brain cavity, especially at the front just above the eyes,
is much, much bigger.
Now, the brain is a really important organ, and making a change
to a brain is something that's quite difficult to do,
as we can see from genetics.
Yes, we do.
And so there's something really, really amazing that we can do
with DNA sequence analysis which allows us to actually
figure out which are the important genes.
And so, to explain this to you, I'm going to tell you a story.
And it's a true story, and it takes place in World War II.
So, the Air Force wanted to reinforce their planes,
so they had this idea but they would reinforce the parts
of the planes that get lots of bullet holes.
So they brought in a statistician to help them, they wanted him
to count the bullet holes and figure out where they are.
But in order to picture this, and to figure out the kind of
challenge this was, we're going to do something.
So you all have paper aeroplanes under your seat.
So just take them, don't do anything with them yet.
OK.
So if you just take a quick look at those,
you'll see that they have holes punched in them.
So that's like a bullet hole.
And so what I want you to do, when I give you the word
- don't anybody go early - I want you to throw those aeroplanes,
and I want you to aim for me. Not yet, not yet, please!
You aim for me because basically I'm on home base, OK?
Are you ready?
Steady?
Go!
SHE SCREAMS
SHE LAUGHS
OK!
Well, that worked!
OK, so the job the statistician had then, these are all the planes
that made it back to home base, and he wanted to look at these.
So, I need to mark, I need to keep track of what's happening.
OK, I'll mark them on this. Alice, you can give me a little hand here.
So this one has a bullet hole there.
So you can take that from me. Yeah.
What I'm going to do is I'm going to make little marks
on this plane. So there's one there... There's one on the wing.
One on that little bit of the wing. Yeah.
OK, this is going to take forever. We need a bigger plane!
Thank you! OK.
So, this plane, we've already collected all these data.
So this is what the statistician had to do.
He had to collect the information from all the different planes
that came back, and he mapped them onto a picture of the plane.
And the legend is that the Air Force's first instinct was,
"Well, we're going to patch up those bits of the plane
"that have loads of bullet holes in them".
But the statistician said to them, "No, you've got it wrong,
"really, because actually we notice these parts of the plane
"that have no bullet holes in them," so what's happening there?
Well, they're the planes that didn't come home.
They're the ones that had really bad damage they couldn't fly with.
These are the bullet holes that allowed the plane to fly,
despite the damage.
So, these parts of the plane are things like the engine,
or the cockpit, or the steering gear.
So by looking at the pattern of bullet holes, you can see
the important parts and the less important parts.
And it turns out we can do this same kind of analysis
with gene sequences.
So, if you imagine for a moment that this is a genome.
Then we had some genes in the genome where lots of mutations happen.
So, the DNA changes, but it doesn't really matter.
So, there's a change, but it's not a significant change.
And then there are other parts of the genome,
other genes, that they really matter, and when you get a change
in them, it really affects the individual.
So they can't survive and thrive as well.
And if we look across mammals and we say,
"Which are the genes in these really important areas?",
We find that there's especially, in these parts of the genome,
it's especially genes that are involved in your brain.
So genes that work in your brain.
But something really changed in human evolution.
So, in early human evolution, these brain genes started
changing quicker. They started evolving faster.
So this is a really unusual pattern, and this tells us that something
was driving that change, something really important had happened.
So, in order for those mutations to start appearing and then building
up and creating this big difference in brains and getting brains to grow
larger, there must have been a significant advantage in growing
a bigger brain. And anthropologists have racked their brains
about what that could possibly be that was driving this increase
in brain size in human evolution.
They said, "Our ancestors must have been working together in teams
"on the African plains, as hunters, so maybe it's cooperative hunting,
"maybe that's what's driving this increase in brain size".
But then, hunting dogs and lions are great at cooperating in hunting,
and their brains aren't very big at all.
So then apologists said, "Well, maybe there's something else.
"Maybe it's stone tools, maybe you need a big brain
"in order to be able to make stone tools."
But actually, that turns out not to be likely either
because our ancestors started making stone tools more than three million
years ago, when again, their brains were pretty small.
There's another group of anthropologists
who think they've got a hypothesis which stacks up when it comes
to brain size, and I need a volunteer now to help me
explore that hypothesis.
I'm particularly drawn by Christmas jumpers, so I'm going to pick
you with a fantastic reindeer Christmas jumper. Come on down.
APPLAUSE Jasmine, right.
OK, I've got a bit of a challenge here for you, Jasmine.
What we've got here are some cubes, and the cubes represent brain size.
In fact, they represent a very special bit of the brain,
they represent the grey matter on the outside that we call
the neocortex, and we've scaled it to body size,
so this must be an animal with a very small amount of neocortex,
and this must be an animal with a large amount of neocortex.
Underneath these cubes, that represent that different brain size,
we've got a clue as to what it is that's driving brain size increases,
or explaining brain size increases.
So what I'd like you to do is lift up each of these cubes,
and we'll reveal a score for each species.
Here we go, then, what's the score for this one?
Oh! The score is one.
And this species is...
..a slow loris.
A very cute type of primate.
OK, what about this species here?
Let's reveal a score for this one.
Oh, that's a lot.
That's 17... I can count very quickly! ..small cubes.
And this species is a spider monkey.
What about this one? What's the score for that one?
Oh, 54 small cubes!
LAUGHTER
This one is a chimpanzee.
And then finally, would you like to lift that big cube?
Ah! There's a pile of people underneath it.
This is a human... LAUGHTER
..and what these scores...
LAUGHTER
What these scores represent,
Jasmine, is the size of social group that these animals normally live in.
So the slow loris is a very solitary creature.
It doesn't have any friends. It just lives on its own.
Spider monkeys are a little bit more gregarious.
They live in a social group which averages 17,
chimpanzees, even more.
Average group size of 54.
Humans, on average, we have 150 friends,
and that's not just acquaintances, that's people we know pretty well.
Jasmine, thank you for revealing the secret of big human brains.
Thank you very much. APPLAUSE
So, it turns out, then, that it's most likely
that our big brains are all about making friends,
making friends and keeping friends, making those connections.
After all, we are quite puny apes, and we've done ever so well
for ourselves as a species, and we've managed to expand
across the whole world, and what we're going to do now
is map out those expansions, and I need two volunteers to come
and help me colonise the world.
There's somebody in a blue T-shirt, second row to the back.
Yes, you! Come down.
Aoife, have you got a volunteer your side? Yes.
Hello. I've got Tessa here.
Come on down. Come on down. APPLAUSE
Wonderful. Come here, turn around.
So, what's your name? Shareen.
Shareen, lovely to meet you.
So, Tessa and... Shareen. Shareen, what we're going to ask you to do
is start in Africa, because that's where our species starts,
so can you find Africa on the map?
Plant your feet on it, occupy it.
That's where our species starts, and our species originated in Africa
about 300,000 years ago, so you can each put a pair of feet
firmly on Africa.
We might need to reload these as we go. We might. OK.
So, we start in Africa, plant them on the map.
You can walk around in Africa a bit, you're all over Africa.
So, our species was just an African species for a few hundred thousand
years, and then about 100,000 years ago...
Tessa, if I move you backwards, you can start to come out of Africa.
Make a little trail of footprints, and you can come all the way
along here into Asia. Do you need a bit more paint?
And you can come along here, through south Asia...
Do you want to come all the way down into Australia?
By 65,000 years ago, modern humans had reached Australia!
Yay! Fantastic! APPLAUSE
I'll move you back over here. And now, Shareen, if you...
Are you nicely loaded up with paint?
You can start making your way into Europe, if you like.
So From about 50,000 years ago, and you can walk all the way
over to Britain... Can you see Britain on the map?
By 40,000 years ago, modern humans, Homo sapiens
like us had reached Britain. Lovely. APPLAUSE
Tessa, I've got a bit more work for you to do.
Start from here in South Asia, and you can walk all the way
up to the north, up to the coast of the Arctic Ocean by 30,000 years
ago, come over here. You can walk across here.
Actually, there's a land bridge here, because the sea level is low,
and you can pop across into Alaska, and now the ice is melting
in Alaska, and you can walk all the way down to South America.
We've colonised North America.
That's the Clovis hunters of North America, and we've got people
going all the way down into South America
and we have colonised the world! Yay!
APPLAUSE
Fantastic! Well done, Shareen!
Brilliant handiwork, I think there, Shareen and Tessa.
Or I should say, footwork.
We've colonised the globe, good work!
Thank you very much. Well done! APPLAUSE
It took a while to get into Europe, didn't it?
It did, there was a little bit of hanging around.
I think they might have met some friends around here.
Oh, indigenous European people.
Well, these earlier humans who were already there
before the modern humans got there, Neanderthals.
So the Neanderthals where the inhabitants of Europe
before our lot got there, and we used to think they were entirely
separate. Looking at their bones, we thought there was never any real
interaction between modern humans and Neanderthals,
but genetics has changed all of that.
Yes, so what we can do now, we can actually get DNA
out of these really old bones.
So, we've been able to get DNA out of Neanderthal bones,
and this revealed some really interesting surprises, because
when we look at the Neanderthal DNA, you could see that it didn't look
actually totally different from human DNA.
So, as you know, you got half your DNA from your mum
and half from your dad,
so 50-50, and then you've got about 25% of your DNA from
each of your grandparents, and then different amounts
from other ancestors, and when we look at people today,
we find we have chunks of DNA that are from a Neanderthal ancestor.
I've got a bit in my genome. Me, too.
There's only one way to get a chunk of DNA from somebody else.
Yes, shenanigans. Shenanigans. Something went on!
There was some serious interaction between modern humans
and Neanderthals. You're shocking the parents.
And it's not just Neanderthals, there's these other species
who were around over here in Asia, and we met up with them as well.
We don't... Well, they may be a species,
they may just be a slightly different set of people.
They're called the Denisovans. My view is that they are
the same species. We're all the same species because of all this mixing.
Do you think? Yeah. That's something we disagree on.
I say from bones, Neanderthals are a different species,
but genetically, you're saying they're the same.
See, scientist don't always agree. No.
But with the Denisovan, there's so little you can say, anyway.
There's so little, in terms of bones.
A finger bone and three teeth, I think.
Mm-hm. But we can get really good DNA...
Even though it's just a tiny bone, the DNA inside it was really well
preserved, so it's really good DNA sequence, and if we look at people,
especially people from around this part of the world,
we see that they have chunks of DNA from Denisovans.
But we've got quite a lot of Neanderthal DNA hanging around,
haven't we? Yes. We all have chunks of Neanderthal DNA.
But we have different chunks of DNA.
So if I were to take all the different chunks and tile them
together, we would get about 70% of the Neanderthal Genome
is in people walking around today.
I can do better than that, Aoife. Can you?
I can show you a whole Neanderthal.
APPLAUSE
So, with the help of some quite amazing prosthetics,
we have transformed a modern human into an ancient Neanderthal
and we can see that there are differences in the face shape.
She's got a very big brow ridge compared with us modern humans,
and actually, she has a lump at the back of her skull as well,
which you can't see under all this hair, but the skull shape
is also different shape to ours, too.
A bit long and low, compared with our more globular face shapes,
or head shapes.
She's got a very chunky jaw, but actually, she looks similar enough
to us that I don't think you'd really notice
if she was walking down the street, would you?
And we keep on finding more clues that Neanderthals
were more like modern humans than we thought,
and one of those clues is in what she's holding in hand.
So, this is a shell, and it's a replica based on one that was
dug out of a cave in Spain, and it's a scallop shell
that's been pierced, so perhaps used as a pendant,
and also painted with red ochre.
So it seems that Neanderthals were interested in decoration
and art in the way that we know our own modern human ancestors
were as well.
So perhaps a lot more similar to us than we previously expected.
Anthropologists for a long time have wondered whether Neanderthals
had language like we do, and that's something we may not ever know.
I mean, can you speak?
Of course I can speak!
We've solved the riddle. APPLAUSE
Thank you.
Although Neanderthals have left a little bit of themselves behind
and still alive in the form of fragments of their DNA
in our genomes, as a group of people,
they had died out by 20,000 years ago.
We don't find their fossils any more, but modern humans survived
through the peak of the last ice age when the ice sheets descended
over northern Europe and over North America,
and it's at this particular time that we see an amazing
explosion in art.
We see our ancestors making fantastic sculptures out of bone
and ivory, and they also painted the caves that they lived in,
and here's a wonderful painting of an ancient human in a cave,
painting some of the animals that are in her environment
and there's a child holding a lamp there, which has properly got some
animal fat in it, burning away, so that she can see what she's doing.
And you might think that this seems really frivolous,
that these are people surviving through the depths of the Ice Age
and shouldn't they be out, hunting and gathering
and keeping their families alive?
What are they doing painting caves and making art?
But it's not frivolous.
Art is a really important part of the way that we communicate
with each other, and this really underpins our success as a species.
We carry on expanding, we carry on making culture.
And what we see from the genetics is that, throughout our history,
we've been moving and mixing with archaic humans
and with modern humans, and we see this continuing today.
The ethnic groups and the populations that we recognise today
are just a mix of lots and lots of people.
In the third lecture, we're going to look at human diversity today,
and we're going to find out how those ancient migrations contributed
to the patterns that we see around us today.
And we're going to look at how our DNA influences who we are.
But for now, we're going to close this lecture with a celebration
of all of our ancient hominin ancestors,
everything that they've given us, our love of art, our language,
all of those secrets and gifts tucked away in our DNA,
and we're going to celebrate them all with a little musical number.
Ta-da! APPLAUSE
You can help me here, Alice. Really?
Yeah, I'll just leave you in charge of one. OK? Everybody ready?
See if you recognise this.
SHE PLAYS JINGLE BELLS
CHEERING AND APPLAUSE
The Christmas lectures have been filmed for 82 years,
but a few are missing from the Royal Institution archives.
If you think you might have any recordings hidden away
in your attic, please dig them out and let us know.
The missing lectures are listed on the Royal Institution website.
Thank you.