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? [MUSIC PLAYING] [APPLAUSE] 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-- 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's 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? Hello. [LAUGHTER] It's all right. He's harmless. He does like you. Oh. 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're 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 [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? There's one thing that
makes you a primate. And also, all primates
are really, really good at climbing. [AUDIO OUT] [APPLAUSE] Alex and Dane, that
was absolutely amazing. How wonderful to
see people who can use their bodies in
that way and move around in 3D 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. What do you think, Albert,
to their parkour performance? [GRUNTS] Aww. Oh, I think it was
better than that. Oh well. A big round of applause
for our great ape. [APPLAUSE] Alex and Dane showed
just brilliantly how we can still move
around in 3D 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 clear one
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. [APPLAUSE] 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 at her hand. Is this all right, Vicki? Yes, of course. And what I'm trying to do is
put my finger in her hand. And she closes her fingers. [CRYING] She doesn't like it. Oh, no, Aria. I'm sorry, poppet. [CRYING] Oh. It's OK. Oh. 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. [CRYING] Oh, baby. Good girl. So this reflex disappears
by about six months of age. But it's something
that we think is leftover 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 a 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 leftover 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. Another gentle
round of applause. Thank you. [APPLAUSE] 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
in this amazing grasp reflex that we're all born
with but 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 a 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 is
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 is a
great example of that. So we'll 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, base 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 there with
the green grapes, Esme. Are you right or left handed? I am right-handed. OK. Can you put your left
hand behind your back? Lovely. And what's your name? Lena. Lena. So Esme and Lena,
you're going to be pitted against each other in
a grape picking challenge. You're both right-handed. So Lena, 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 grapes off-- I'll put the bowls
around that way for you as well, as it might
be a bit easier. Thank you. 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-- 1, 2, 3, 4, I
declare a thumb war. Go! [MUSIC PLAYING] 15 seconds. Who's going to do
better at this? [LAUGHTER] I think that might be cheating. [LAUGHS] All 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, you're much worse at plucking grapes. Do you know what, Lena? We've done it with so
many people this afternoon in rehearsals, and
we always ended 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. [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
Lena and Esme for testing out their thumbs. Thank you. [APPLAUSE] So lots of things,
then, that we've got in common with
our primate cousins-- anatomy, behaviour. But actually these
similarities go down to the level of molecules
inside your cells. 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] Thank you! Oh! 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 5 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'd like the people in
row 4 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. And 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, so
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 there's a piece
of DNA that's either been inserted into
the human genome, or deleted from the
chimpanzee genome. But 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's 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. [LAUGHS] OK. OK, then. Yeah. We'd better do
countdown, haven't we? OK, yeah, we should do
a countdown for this. OK. Three! Two! One! [POP] OK. So thank you so much. So the people in
row 5 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 were 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, a 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 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 is 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. Christmas jumper in
the second row back, please come down That's
a fantastic jumper. [APPLAUSE] Thank you very much
for that volunteering. You're very brave. What's your name? Steven. Steven. Right. Now, Steven, 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. And we've got a little
video to show you of a capuchin monkey making
its way across a tightrope. [LAUGHTER] So, Steven, 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-- 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 each 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? 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. Steven. You all right? [LAUGHS] 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 can 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! [APPLAUSE] Steven, 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. [APPLAUSE] We can do this thing of
walking along a tightrope and suspending ourselves-- or
at least stabilising ourselves by holding onto 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 4 to 3 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. Se 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 leftover 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
2 million years ago with a new species appearing. And this species is
called Homo erectus. And Homo erectus appears
about 2 million years ago. This particular reconstruction
is based on a fossil for 1 and 1/2 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 had gaps at the ends. They haven't fused yet,
because 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 was 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 is 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, we can 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 is a sport scientist, 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, low 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. Because 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 these
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 has also
swallowed one of these. This is a really
small thermometer. And he was asked to do
this by Doctor 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, I have to say. 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. Yeah. And is this the same
then for other animals? Well, if we were to have
a gazelle or a cheetah during 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 tomcat. 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-- Oh, yeah. --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. Yeah. There's a spike. Uh-huh. And we've got these balloons. And we've got these balloons. So this balloon represents
the amount of sweat that a 70-kilogramme dog sweats
out during an hour of exercise. 70 kilogrammes is
bigger than me. Yeah. Its quite a big dog. 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? 3, 2, 1! [POP] [SHRIEK] OK. OK. So it wasn't as
bad as I expected. So that's a 70-kilogramme-- No, it's not too bad, is it? That was a 70-kilogramme dog. Dogs don't sweat that much. They have to stop, and they had
to bring their temperature down by panting. 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. 3, 2, 1! [POP] [SHRIEK] 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 now, yeah. 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 3, 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
5 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're able to
run long distances. And we think this was
incredibly important to our ancient ancestors--
people like Nariokotome Boy. So going back 2
million years ago, we've got the expansion
of grasslands in Africa-- savanna. And with the expansion
of these 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. [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-- Go on then, Antony. Bash a couple of flakes
off and see what happens. And he's using a cobble
to break these flakes off. That's quite a good one. Oh, 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 is 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 ax. She's making flakes which
are useful as knives, but this is useful,
too, isn't it? Yes, absolutely. Yeah. It's a multi-purpose 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 that, I think, this tells
us something really important about the minds of
these tool makers. 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. 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 Anthony. That was brilliant. Thank you. [APPLAUSE] 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're, 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. And 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 that 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 get 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. Oh, we've got one already. Very good, now. Yeah. More. And this is totally normal. It's actually expected that
different people stand up at different times. So this is amazing. Everybody's starting
to stand up. So-- ba-ba-- I'm running around the stairs. What was the flavour
change for you? Boring. Boring. OK. [LAUGHING] It changed to boring. Did it start out interesting? What did you think? Sweet? It can change to sweet. What did you think? Sweet. Interesting. This is very good. What did you think? Did it change for you? 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've 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. [POOF] Woo! 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 could 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 to 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 am 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 that 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 what kind of challenge this was,
we're going to do something. So you all have paper
airplanes 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 airplanes. And I want you to aim for me. Not yet. Not yet, please! I want you to aim for
me, because basically I'm on home base, OK? Are you ready? Steady? Go. [SHRIEK] [LAUGHS] [APPLAUSE] 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 could give
me a little hand here. So this one has a
bullet hole there. So you could take that from me. Yeah. And what I'm going to
do is I'm going to make little marks on this plane. So there's one there. Yeah, there's one on the wing. One on that little
bit of the wing. There's one on that bit of wing. I'll do it. 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 have 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, well, 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. Woo! 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 these
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
wrapped their brains about what that
could possibly be that was driving this
increase in brain size in human evolution. They said, well, our ancestors
must have been working together in teams on the African
plains as hunters. So maybe it's
co-operative 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 anthropologists
said, well, maybe there's something else. Maybe it's stone tools. Maybe you need a really
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. Jasmine. Right. OK, I've got a
bit of a challenge here for you, Jasmine. What we've got
here is 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 then this must be an
animal with a large amount of neocortex. Underneath these cubes that
represent 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 will reveal a
score for each species. Here we go, then. What's the score for this one? Ah. The score is 1. And this species
is a slow loris. A very cute type of primate. OK. What about this species here? Let's review the
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. This one is a chimpanzee. And then finally, would you
like to lift that big cube? There's a pile of
people underneath it. This is a human. 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
all 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 on second row to the back. Yes, you. So come down. Aoife, have you got a
volunteer on your side? Yes. Hello. I've got Tessa here. Come on down. Come on down. [APPLAUSE] Wonderful. Just come here. Turn around. So what's your name? Shereen. Shereen. Lovely to meet you. So-- OK, so Tessa and-- Shereen. Shereen. 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? Go on. 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. Now we might need to
reload these as we go. We might. OK. So, you 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. Then about 100,000 years ago,
Tessa, if I move you backwards, you can start-- [INTERPOSING VOICES] --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! I'll meet you back over here. And now, Shereen, 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. Yes. Very nice job. [APPLAUSE] Tessa, I've got a bit
more work for you today. Start from here in South Asia. And then 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's 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. We have colonised the world. Yay! Fantastic! Well done, Shereen. Brilliant handiwork, I think
there, Shereen and Tessa-- or I should say footwork. We've colonised the globe. Good work. Thank you very much! Well done! Well done. Thank you. 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. Indigenous European people? Well, these earlier
humans who were already there before the modern
humans got there-- Neanderthals. So the Neanderthals were
the inhabitants of Europe before our lot got there. And we used to think they
were entirely separate. Looking at their bones, we
thought that there was never any kind of real interaction
between modern humans and Neanderthals. But genetics has
changed all 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 looked
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, right? 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 DNA. Yeah, me too. Yeah, we all have. There's only one way
to get a chunk of DNA from somebody else. Yeah. Shenanigans. Shenanigans. Something went on. There was some
serious interaction between modern humans
and Neanderthals. You're shocking the parents. [GASP] And it's not just Neanderthals. No. There's these other species who
were around over here in Asia. And we met up with them as well. Well, they may be a species. They may just be a slightly
different set of people there. I call them Denisovans. My view is that they're
the same species, and we're all the same species,
because of all this mixing. Do you think? Yeah. That's something we disagree on. That is something
we disagree on. I'd say from the
bones, Neanderthals are different species,
but genetically you're saying they're the same. See, scientists
don't always agree. No. But with the Denisovans, there's
so little you can say, anyway. There's so little
in terms of bones-- a finger bone and
three teeth, I think. But when we can get
really good DNA, actually, even though
it was just a tiny bone, the DNA inside it was really,
really well preserved. And 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, don't we? Yeah, yeah. So we all have chunks
of Neanderthal DNA. But we have different
chunks of DNA. So if I was to take all
the different chunks and tile them together,
we get about 70% of the Neanderthal genome is
in people walking around today. I could do better
than that, Aoife. I can show you a
whole Neanderthal. [LAUGHS] [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's
also a 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 these clues is in
what she's holding in her 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 ocher. 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 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! [LAUGHS] We've solved the riddle. 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 probably
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 hominid 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. Da-da! You can help me here, Alice. Really? Yeah, yeah, yeah. I'll just leave you
in charge of one. OK. Everybody ready? See if you recognise this. [PLAYING "JINGLE BELLS"] [CYMBAL CRASH] [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.
