0:00:06 > 0:00:09The shape of your face,
0:00:09 > 0:00:12walking on two legs,
0:00:12 > 0:00:14the way you see the world...
0:00:14 > 0:00:17What makes you the person you are?
0:00:22 > 0:00:27The story of each and every one of us can be traced back millions of years
0:00:27 > 0:00:30to the plains of ancient Africa.
0:00:33 > 0:00:36The answers to the question "What makes us human?"
0:00:36 > 0:00:41lie buried in the ground in the fossils and other traces of our ancestors,
0:00:41 > 0:00:48but also lie deep within our own bodies, in our bones, flesh and genes.
0:00:51 > 0:00:55As an anatomist, I'm fascinated by the way our bodies
0:00:55 > 0:00:59have been sculpted by our ancestors' struggle for survival.
0:01:05 > 0:01:10But why did we leave behind the other apes in the forest...
0:01:12 > 0:01:15..to become the only one of our kind left today?
0:01:17 > 0:01:20How did living into old age,
0:01:20 > 0:01:26and learning from each other, shape our large, clever brains?
0:01:28 > 0:01:32The way our brains work today, the way we think, feel and behave,
0:01:32 > 0:01:37is a direct consequence of our ancestors' struggle for survival.
0:01:37 > 0:01:41But where other human species died out,
0:01:41 > 0:01:44was it really our brains that gave us the edge?
0:01:46 > 0:01:51I want to find out how our brains led us to be the successful, global species we are today,
0:01:51 > 0:01:56and why we are the only humans left on the planet.
0:02:14 > 0:02:17Our bodies are amazing machines,
0:02:17 > 0:02:21honed over millions of years of evolution.
0:02:24 > 0:02:31But our basic flesh and bones aren't that different from our closest ape relatives, chimpanzees.
0:02:33 > 0:02:38Fundamentally, we are just another species of ape,
0:02:38 > 0:02:42but we do feel ourselves to be different, to be special,
0:02:42 > 0:02:45and that comes down to the very striking difference between us
0:02:45 > 0:02:51and any other species on Earth. And that lies up here.
0:03:02 > 0:03:05We are creatures of the mind.
0:03:05 > 0:03:11We have an ability to think, imagine and create,
0:03:11 > 0:03:13that has changed the world.
0:03:14 > 0:03:20We have the ability to ponder the very nature of our own existence.
0:03:21 > 0:03:26The emergence of the human mind is one of the great mysteries,
0:03:26 > 0:03:31and it's a question which has been tackled by religion, philosophy and science.
0:03:31 > 0:03:38And, as a scientist, I believe the answer is physical, the mind is a product of the brain.
0:03:38 > 0:03:42And if we want to understand the way we think and act today,
0:03:42 > 0:03:44we need to look at where we've come from.
0:04:10 > 0:04:14This is the Rift Valley in east Africa.
0:04:14 > 0:04:18It's here that the human story began.
0:04:25 > 0:04:30This beautiful landscape is incredibly important to our story.
0:04:30 > 0:04:34So many traces of our ancestors, going back millions of years,
0:04:34 > 0:04:36have been found here.
0:04:36 > 0:04:40So if we want to understand who we are,
0:04:40 > 0:04:43there's not really a better place to start looking.
0:04:45 > 0:04:48Fossilised fragments of bones unearthed here
0:04:48 > 0:04:55show that we are the last of a large and ancient family of human-like creatures.
0:05:00 > 0:05:06I'm going to use the shadow cast by these trees to recreate the human family tree.
0:05:08 > 0:05:11It's more like a bush than a single branch of a tree,
0:05:11 > 0:05:18but what I'm really interested in here is the size of the skulls.
0:05:18 > 0:05:23To begin with, this is Sahelanthropus tchadensis, from Chad,
0:05:23 > 0:05:26dating to about six-seven million years ago.
0:05:26 > 0:05:31He's an upright walker, but has a tiny brain, about the same size as a chimpanzee's.
0:05:38 > 0:05:43Around four million years ago, we see something a bit more human appearing, the Australopithecines.
0:05:43 > 0:05:46This is Australopithecus africanus, a slightly bigger brain.
0:05:51 > 0:05:55The next character is the first member of our own genus, Homo,
0:05:55 > 0:06:01Homo habilis, the handyman, the tool maker, at around two and a half million years ago.
0:06:05 > 0:06:09This is Homo erectus, brain size getting bigger,
0:06:09 > 0:06:12appears around about two million years ago.
0:06:15 > 0:06:20Jumping forwards in time, we get to Homo heidelbergensis,
0:06:20 > 0:06:23appearing around 600,000 years ago.
0:06:23 > 0:06:25The brain size is nearly as big as ours.
0:06:30 > 0:06:35And finally, there's just one twig surviving to the present day,
0:06:35 > 0:06:37and that is us.
0:06:37 > 0:06:43In fact this is me - this is a replica of my skull.
0:06:43 > 0:06:45So I'm going to represent Homo sapiens.
0:06:45 > 0:06:48Looks like a fairly decent brain size in there.
0:06:59 > 0:07:04The skulls of our ancestors clearly show an increase in brain size.
0:07:06 > 0:07:09This important change defines our story.
0:07:18 > 0:07:25Our evolutionary journey starts with the chimpanzee-like Sahelanthropus, in the forests of Africa.
0:07:28 > 0:07:34The first apes to walk out of the forest on two legs were the Australopithecines.
0:07:36 > 0:07:44And a million years later, Homo erectus, with a very tall, very modern-looking physique,
0:07:44 > 0:07:46strode out onto the African savannah.
0:07:49 > 0:07:54And all this time our ancestors' bodies and brains were getting bigger.
0:07:55 > 0:08:01Today, our brains are almost four times the volume of our earliest ancestors,
0:08:01 > 0:08:05shaping the way we think and behave.
0:08:08 > 0:08:12So why did our ancestors' brains get bigger?
0:08:12 > 0:08:13It's such a difficult question
0:08:13 > 0:08:17and we're not going to be able to answer it just by looking at their skulls.
0:08:17 > 0:08:22But what we can do is look at the wider context, the environment they lived in.
0:08:22 > 0:08:29What was going on around here at the time our ancestors' brains were expanding?
0:08:39 > 0:08:44The Rift Valley has been called the crucible of human evolution.
0:08:46 > 0:08:50It's long been thought that it was the struggle to survive here,
0:08:50 > 0:08:54in this harsh habitat, that drove our evolution.
0:08:59 > 0:09:05But recently, scientists have been taking a closer look at the rocks here,
0:09:05 > 0:09:12looking back in time to see what the environment was really like millions of years ago.
0:09:12 > 0:09:17And here, on the side of this hill, is a bit of that environmental sequence.
0:09:17 > 0:09:23And you can read it. This area here, that I'm standing on, this white, chalky layer,
0:09:23 > 0:09:30is sediment from the bottom of an ancient lake. And inside it, there are microscopic algae diatoms,
0:09:30 > 0:09:33that tell us that this was a very deep lake.
0:09:33 > 0:09:37As we move up to this layer here, the lake is drying out,
0:09:37 > 0:09:42it's becoming much more salty. There are diatoms in here that are salt-loving.
0:09:42 > 0:09:49Then there's another change and we've got this yellow/brownish layer here, and that is an ancient soil,
0:09:49 > 0:09:55and it's even got the root patterns within it of the grass which once grew on it.
0:09:55 > 0:10:01And then this grey layer here is volcanic ash from a distant volcano,
0:10:01 > 0:10:05the ash cloud billowed over and dumped right here.
0:10:05 > 0:10:10As we walk further up, we start to get another white layer, so we're moving into a lake again.
0:10:10 > 0:10:15And then the lake dries out, and we're left this time with a salt flat,
0:10:15 > 0:10:18and you can see the surface of it just there.
0:10:18 > 0:10:24And then after the salt flat, we're back to a lake again, with this white sediment.
0:10:24 > 0:10:28And that spans just 5,000 years.
0:10:37 > 0:10:42During our evolution, this area was changing every few hundred years.
0:10:45 > 0:10:50This rapid rate of change would have made it difficult to adapt physically.
0:10:52 > 0:10:57Instead, the apes here learned to change something else - their behaviour.
0:11:01 > 0:11:06Only those individuals who were clever enough to find new ways
0:11:06 > 0:11:10of getting food and water as the landscape changed
0:11:10 > 0:11:13would have survived and passed on their genes.
0:11:15 > 0:11:18At the time our ancestors' brains are expanding,
0:11:18 > 0:11:23they were living in this highly fluctuating environment.
0:11:23 > 0:11:26And one theory says the two are intrinsically linked,
0:11:26 > 0:11:33that those big brains allowed our ancestors to develop highly flexible behaviour.
0:11:33 > 0:11:37So rather than that old tale of ancient humans adapting to life on the savannah,
0:11:37 > 0:11:41it seems that they were evolving to be adaptable,
0:11:41 > 0:11:47to be able to survive and flourish in a range of different environments.
0:11:48 > 0:11:53The way our ancestors might have behaved isn't preserved in the fossil record,
0:11:53 > 0:11:57but clues can be found in the behaviour of our closest cousins.
0:12:02 > 0:12:07Here at Edinburgh Zoo, researchers have been studying chimpanzees,
0:12:07 > 0:12:11to get insights into the origins of human intelligence.
0:12:13 > 0:12:18Hello. What do you think of me? I'm a bit like you.
0:12:21 > 0:12:26Chimps and humans share a common ancestor, going back some seven million years ago.
0:12:26 > 0:12:31So, if we compare ourselves with chimpanzees, then we can assume
0:12:31 > 0:12:35that any behaviours we share may have been there in our ancestors,
0:12:35 > 0:12:40whereas any differences have arisen on the way to becoming modern species.
0:12:44 > 0:12:48Like us, the chimps live in a tight-knit social group.
0:12:48 > 0:12:52But the social politics here are being thrown into turmoil
0:12:52 > 0:12:56by the arrival of a new group from the Netherlands.
0:12:56 > 0:12:59Betsy Herrelko is studying how they react.
0:12:59 > 0:13:03So coming up in the middle is Claus, the dominant male from the Dutch group,
0:13:03 > 0:13:06and we've got Kindia and Qafzeh, the dominant male from the Edinburgh group,
0:13:06 > 0:13:09who are just starting to kind of throw ropes around
0:13:09 > 0:13:13and it looks like there's a little bit of a face off.
0:13:13 > 0:13:18The Dutch chimpanzees quickly assess who's who in the Edinburgh group,
0:13:18 > 0:13:24working out whom they can challenge and whom they should suck up to.
0:13:24 > 0:13:27Oh, and here we've got a little submission from Lianne,
0:13:27 > 0:13:31so she's showing her bottom to him and she's doing a full bare-teethed grin.
0:13:32 > 0:13:38In this changing power structure, making and keeping political allies is crucial.
0:13:38 > 0:13:43Here we have Claus, with Sophie. Claus is the dominant male of the Dutch group
0:13:43 > 0:13:46and Sophie is a lower-ranking female over there.
0:13:46 > 0:13:51And she's lower ranking, but she's going up to him, she's not appeasing him, but she's trying to touch him,
0:13:51 > 0:13:58just pay attention to him and make sure she's in his good graces, before she feeds right next to him.
0:13:58 > 0:14:03So is it really important for the dominant chimp to have alliances, to have friends in the group?
0:14:03 > 0:14:08It's very much like our political system, you have to play the field and see who can be your ally
0:14:08 > 0:14:11and benefit you in some ways, and when you might need to drop them.
0:14:13 > 0:14:18And if you're clever enough to work out whom you can bully,
0:14:18 > 0:14:23and whom you need to run away from...
0:14:23 > 0:14:26..you can work out other things,
0:14:26 > 0:14:29like how to get that apple from the other side of the fence.
0:14:32 > 0:14:40And it's mental flexibility like this that enabled our ancestors to adapt to their changing environment.
0:14:40 > 0:14:43Looking at the behaviours that we share with chimpanzees,
0:14:43 > 0:14:48it's clear that we've inherited cunning brains from our ancestors.
0:14:48 > 0:14:53We are social animals, we have this acute sense of political awareness.
0:14:53 > 0:14:57We understand what others are doing and where they fit in
0:14:57 > 0:15:01in the social system, and we use that to our advantage.
0:15:02 > 0:15:07But we differ from chimpanzees in a very important way.
0:15:07 > 0:15:13Our ancestors developed a mental ability so useful that it's written into our faces today.
0:15:18 > 0:15:21They say the eyes are the windows into the soul.
0:15:23 > 0:15:25And our eyes are unique.
0:15:27 > 0:15:34We are the only animals on the planet which show the whites of their eyes.
0:15:44 > 0:15:47We can do something that no other animal on Earth can do -
0:15:47 > 0:15:50we can tell what somebody's thinking just by looking at their eyes.
0:15:50 > 0:15:53We can literally read their minds.
0:16:05 > 0:16:10It's something most of us start to do naturally from the age of about four.
0:16:11 > 0:16:15Children use people's eye gaze to tell what they're thinking.
0:16:17 > 0:16:20So the first thing I'd like you to do is,
0:16:20 > 0:16:23can you guess which sweets I like?
0:16:23 > 0:16:25- No.- I think this.
0:16:28 > 0:16:29Chocolate mice.
0:16:31 > 0:16:34You're so clever. How did you guess that?
0:16:34 > 0:16:37Because, cos you... cos your eyes were looking at them.
0:16:37 > 0:16:40Oh! And you're right.
0:16:40 > 0:16:42Well, that seemed very simple,
0:16:42 > 0:16:46but in fact our ability to read minds goes much further than that.
0:16:46 > 0:16:51We can tell when people are happy, or sad, honest, or deceitful.
0:16:51 > 0:16:57This mind-reading means that we don't always take things at face value.
0:16:58 > 0:17:01'So here's another quick test.
0:17:01 > 0:17:04'I've hidden a sweet under one of the three cups.
0:17:07 > 0:17:11'Can they guess where it is, if I tell them one thing...'
0:17:11 > 0:17:15I'll give you a clue - he might be under the blue cup.
0:17:15 > 0:17:18'..But my eyes tell a different story.'
0:17:18 > 0:17:19- Green.- Green.
0:17:22 > 0:17:25'The kids immediately realised I was fibbing
0:17:25 > 0:17:29'and, by reading my mind, go straight for the sweets.'
0:17:29 > 0:17:32These children are doing something incredibly complex,
0:17:32 > 0:17:38they must be thinking, "I know you want me to think the sweet is under here,
0:17:38 > 0:17:45"but I think you actually know it's there." So they're seeing through my deceit.
0:17:45 > 0:17:48And this degree of mind-reading ability,
0:17:48 > 0:17:55this understanding ourselves and others and what others are thinking, is unique to us,
0:17:55 > 0:18:01and it underpins all of our ability to share knowledge and ideas with each other.
0:18:05 > 0:18:08Our unique ability to read minds is thought to be linked
0:18:08 > 0:18:16to one of the most important ideas to emerge in our evolutionary history - learning to make tools.
0:18:20 > 0:18:26The ability to make stone tools is one of the defining features of humans, of our genus Homo.
0:18:26 > 0:18:30And tools like this were made by the earliest humans, Homo habilis,
0:18:30 > 0:18:33going back about 2.5 million years ago.
0:18:39 > 0:18:42Homo habilis wasn't much like you or me.
0:18:42 > 0:18:45He only had a brain half the size of ours.
0:18:47 > 0:18:54Yet he's the first ancestor that we know had tools, and that's why he's called Homo, meaning human.
0:18:56 > 0:19:01And these tools enabled him to overcome the challenges of his environment.
0:19:04 > 0:19:08These tools allowed them to extend their own biological capabilities.
0:19:08 > 0:19:12It was as though they were arming themselves with the tusks,
0:19:12 > 0:19:17the sharp teeth and the claws that they didn't naturally possess.
0:19:17 > 0:19:23And, crucially, those tools meant that they could get to a much wider range of food
0:19:23 > 0:19:27than you'd normally expect an ape to be eating.
0:19:27 > 0:19:30And, over time, those tools became more complex.
0:19:35 > 0:19:40Within a million years, a new species had evolved, Homo erectus,
0:19:40 > 0:19:45slender and tall, with a larger brain that his predecessors.
0:19:48 > 0:19:54And that brain was being shaped by his tool-making technology.
0:20:01 > 0:20:07Here at Olorgesailie, you can see where Homo erectus people made their tools.
0:20:07 > 0:20:10Incredibly, they still lie scattered across the ground,
0:20:10 > 0:20:15where they were dropped by ancient hands a million years ago.
0:20:20 > 0:20:24Doctor Rick Potts has been studying how they were made.
0:20:24 > 0:20:30It's a complex process, which starts with quarrying the rocks.
0:20:30 > 0:20:38We're here at a place where the hand axe makers came, almost a million years ago,
0:20:38 > 0:20:41and they quarried the volcanic rock
0:20:41 > 0:20:46to test which rocks were the best ones to take away as hand axes.
0:20:46 > 0:20:49So you're absolutely sure these rocks have been quarried
0:20:49 > 0:20:53- by human hand, they're not just naturally broken? - Yeah, let me show you.
0:20:53 > 0:20:57What we found here were thousands and thousands of stone-flaking debris,
0:20:57 > 0:21:01and so we're pretty sure that, where you're sitting, a Homo erectus sat,
0:21:01 > 0:21:04one of these hand axe makers, a million years ago,
0:21:04 > 0:21:10- making stone tools, testing the rock and seeing which hand axes to take away.- That's amazing.
0:21:10 > 0:21:14- This is a moment in time, that long ago.- It is, yeah.
0:21:15 > 0:21:20I sat in the spot, just like you did. It's extraordinary,
0:21:20 > 0:21:24it's an intuitive connection to these ancestors, to the hands,
0:21:24 > 0:21:26the things that they were capable of.
0:21:26 > 0:21:29You can see right here,
0:21:29 > 0:21:32where there is a large flake scar.
0:21:32 > 0:21:37- Yep.- And that was struck by using an enormous hammer stone right here.
0:21:37 > 0:21:40They were very strong, these hand axe makers.
0:21:40 > 0:21:45And we saw dozens of examples of rocks with imperfections that were left behind,
0:21:45 > 0:21:50so you can really get a sense of the decisions that these hand axe makers were making right here.
0:21:51 > 0:21:56Once the rocks had been selected, they then needed to be shaped,
0:21:56 > 0:21:59and that's something you really need to be taught,
0:21:59 > 0:22:02because it's far from straightforward.
0:22:03 > 0:22:06The principle here is that you strike the edge,
0:22:06 > 0:22:10and it sets up force that goes through the rock,
0:22:10 > 0:22:12and out from the other side pops a sliver.
0:22:14 > 0:22:16- Oh, wow.- OK? - Yeah, that's a decent flake.
0:22:16 > 0:22:19So there's your flake here. So why don't you have a go?
0:22:19 > 0:22:21OK, I'll try. All right then.
0:22:23 > 0:22:27- There we go. - Ooh, that's, oh, that's a nice one. - There we go, that's a good one.
0:22:27 > 0:22:32- Look at that.- Yeah, that's pretty typical of what you would find at a hand axe site.
0:22:32 > 0:22:36And you can see the platform, or the edge that you struck,
0:22:36 > 0:22:42and this is the piece that came off and the scar where the flake came.
0:22:42 > 0:22:46So the hand axe, when you're finished making it, will be a useful tool in its own right,
0:22:46 > 0:22:51- but the flakes that come off it are also useful?- That's right. The tool can be the sharp flake itself,
0:22:51 > 0:22:55or it can be at the sharp edge of the hand axe.
0:22:55 > 0:22:59- That's why they sometimes call it the Swiss army knife of the Stone Age.- Brilliant!
0:23:01 > 0:23:06Learning to make a Homo erectus hand axe is surprisingly complex,
0:23:06 > 0:23:12and it's only really possible if you understand your teacher's aims and intentions.
0:23:15 > 0:23:20You can imagine Homo erectus children sitting there watching their dads
0:23:20 > 0:23:24- and possibly their mums making these hand axes and learning how to do it. - Exactly, that's right.
0:23:24 > 0:23:31Here is a real hand axe made by Homo erectus from 900,000 years ago.
0:23:31 > 0:23:35Look what you've done, very similar to this, so I think you've done a great job.
0:23:35 > 0:23:39That's brilliant. So that is my very own hand axe, I made that.
0:23:44 > 0:23:51The tool-making culture of Homo erectus was a turning point in human history.
0:23:51 > 0:23:54With tools to butcher meat and protect themselves,
0:23:54 > 0:24:00our ancestors were able to spread into new territory and find food and shelter.
0:24:00 > 0:24:06For over a million years, the hand axe was the cutting edge of stone tool technology.
0:24:06 > 0:24:12A hand axe, together with the flakes that come off it, constitute an incredibly versatile tool kit.
0:24:12 > 0:24:17And all these ancient hand axes that are found across the Rift Valley
0:24:17 > 0:24:22wouldn't be there, were it not for humans' ability to copy from each other.
0:24:28 > 0:24:32Stone Age culture gave us far more than just tools.
0:24:32 > 0:24:38It crystallised in us an ability to learn from one another, and to share knowledge.
0:24:55 > 0:25:00Stone hand axes, and the more complex culture that follows them,
0:25:00 > 0:25:04tell us about the behaviour of our ancestors.
0:25:04 > 0:25:09But they also do more than that, they tell us about their minds.
0:25:09 > 0:25:13Because, in order to be able to make a complex stone tool,
0:25:13 > 0:25:17it certainly helps to be able to understand what other people are thinking.
0:25:17 > 0:25:21But you also have to have a mental image,
0:25:21 > 0:25:25an abstract idea in your mind of what that tool is going to look like.
0:25:25 > 0:25:30And it's been suggested that this mental ability to make stone tools
0:25:30 > 0:25:34is related to something else - language.
0:25:39 > 0:25:41And the plant life was out of this world.
0:25:41 > 0:25:43Her job paid more and it made sense.
0:25:43 > 0:25:49- Once the weather improves, I'll be on the allotment. - What's it called? Brain's gone.
0:25:49 > 0:25:51But I was never very sporty at school.
0:25:51 > 0:25:54We are unique in our ability to speak.
0:25:54 > 0:25:59But the moment when human language first evolved is shrouded in mystery.
0:26:00 > 0:26:04Language is such an important human characteristic,
0:26:04 > 0:26:09but there's no direct evidence of when it evolved.
0:26:09 > 0:26:13We can't even look at the vocal tracts of our ancestors -
0:26:13 > 0:26:17they're made of soft tissue, cartilage, muscles, ligaments, membranes.
0:26:17 > 0:26:20They don't fossilise like bones do.
0:26:20 > 0:26:28The only certainty is that language is central to one human species which emerged in Africa
0:26:28 > 0:26:35around 200,000 years ago, and that is us, Homo sapiens.
0:26:35 > 0:26:37Well, I'd always wanted to go to Machu Picchu.
0:26:37 > 0:26:41We use language in every aspect of our lives,
0:26:41 > 0:26:45from idle gossip to sharing our deepest thoughts.
0:26:45 > 0:26:48Go to Australia, that's even worse.
0:26:48 > 0:26:54Forming this range of sounds involves many parts of our anatomy.
0:26:54 > 0:27:00This is a scan of my own head and neck, showing all the anatomy which I use to produce speech,
0:27:00 > 0:27:05from the lips at the front, there,
0:27:05 > 0:27:09to the teeth, which are there,
0:27:09 > 0:27:13the palate, hard palate and then soft palate at the back there.
0:27:14 > 0:27:18And this enormous mass of muscle here is my tongue,
0:27:18 > 0:27:22which is very important in moulding the sounds coming out of my mouth.
0:27:22 > 0:27:26There's the epiglottis, which protects the larynx, the voice box,
0:27:26 > 0:27:30and, deep within the larynx, the vocal cords themselves.
0:27:33 > 0:27:37Bulb went from my outside light, so he changed the bulb...
0:27:37 > 0:27:42And on this amazing real-time MRI scan, you can see them all in action.
0:27:44 > 0:27:48Air from my lungs is forced between my vocal cords, causing them to vibrate.
0:27:48 > 0:27:55The sound passes upwards and is moulded by my tongue and my lips, emerging as speech.
0:27:55 > 0:28:00Aaaaa, eeeee, oooooo.
0:28:01 > 0:28:03Feel like a bit of a loony!
0:28:10 > 0:28:12Our ability to vocalise our inner thoughts
0:28:12 > 0:28:16gave our species the power to teach and learn
0:28:16 > 0:28:21at a level of complexity no other animal on Earth can match.
0:28:26 > 0:28:31Human language is so much more than just a series of sounds.
0:28:31 > 0:28:38It draws on something else which seems to be uniquely human, and that is symbolic thought.
0:28:38 > 0:28:45When we name something, we create an abstract representation of it,
0:28:45 > 0:28:50and crucially, we can take that idea and share it with someone else.
0:28:50 > 0:28:55With language, ideas are not just our own, they become common property.
0:29:01 > 0:29:06Using language to share ideas, we could build on the knowledge
0:29:06 > 0:29:10and culture of those who had gone before us.
0:29:10 > 0:29:16Over time, our brains evolved to be much larger than those of all our ancestors.
0:29:18 > 0:29:23But there is a price to pay for having a big brain.
0:29:24 > 0:29:26MOANING
0:29:29 > 0:29:30SHE PANTS
0:29:32 > 0:29:39Giving birth is one of the most painful and dangerous experiences women have to endure.
0:29:45 > 0:29:50I've come back to the hospital where I gave birth to my first baby 11 months ago.
0:29:50 > 0:29:55And it's very strange being here - it stirs up a real mix of emotions.
0:29:55 > 0:30:02I can remember back to certainly fear and pain, but also of course immense joy.
0:30:02 > 0:30:08But it does seem rather odd, given that reproduction is essential to the survival of any species,
0:30:08 > 0:30:15that, for humans, childbirth can be so difficult and painful.
0:30:16 > 0:30:19Allionna is giving birth for the second time,
0:30:19 > 0:30:21and although all is going smoothly,
0:30:21 > 0:30:25even a straightforward delivery is challenging.
0:30:25 > 0:30:27SHE WAILS
0:30:28 > 0:30:33And that's all down to the large heads of our big-brained babies.
0:30:33 > 0:30:37- The contraction is good, you rest now. OK?- OK, I'll rest.
0:30:38 > 0:30:41Mm, my baby took quite a while to appear.
0:30:42 > 0:30:49Erm, she started coming and it took about three and a half days for her to actually emerge.
0:30:49 > 0:30:52Erm, and I definitely needed help for that to happen.
0:30:52 > 0:30:55It wasn't something I could've done on my own.
0:30:55 > 0:31:00- Long pushes.- I can't.- Go on, yes you can. Go on, yes you can.
0:31:00 > 0:31:02You need to get the baby out now. OK?
0:31:02 > 0:31:07Humans are the only species that need help to give birth.
0:31:08 > 0:31:13Our babies' heads are so big that it's astounding they can get out at all.
0:31:13 > 0:31:15One more push, please. Go on.
0:31:15 > 0:31:21OK, when you feel the pain, push against that pain, OK? Push hard.
0:31:21 > 0:31:25So you can see the space through which the baby has to pass,
0:31:25 > 0:31:32from the inside to the outside, and it is quite a narrow space.
0:31:32 > 0:31:34If we look at the size of the baby's head,
0:31:34 > 0:31:38you can see that it is going to be a pretty tight fit.
0:31:38 > 0:31:45My baby got her head stuck in that position, which wasn't particularly helpful.
0:31:45 > 0:31:49Let's put her back in a slightly more co-operative position,
0:31:49 > 0:31:55and her head can now drop down inside the pelvis. But it's stuck again,
0:31:55 > 0:32:03so she needs to tuck her chin in, rotate round like that, and then the back of her head can come out,
0:32:03 > 0:32:08and then the shoulders can come out and the baby is born.
0:32:08 > 0:32:09WOMAN SCREAMS
0:32:09 > 0:32:12That's it, go on, keep on going, keep going. Keep going.
0:32:12 > 0:32:17Come on, that's it, that's my girl, well done, that's it.
0:32:20 > 0:32:22Yes, well done, that's it. Well done.
0:32:22 > 0:32:25WOMAN SCREAMS
0:32:35 > 0:32:37BABY CRIES
0:33:00 > 0:33:05We're born with the biggest brain our mother's anatomy can cope with.
0:33:05 > 0:33:09But to ensure that a baby like Reuben can be born,
0:33:09 > 0:33:13he has to come out before his brain is really ready,
0:33:13 > 0:33:16which means he's completely helpless.
0:33:28 > 0:33:32Well, this is Reuben. He's such a perfect little baby.
0:33:34 > 0:33:39But compared with most newborn mammals, his brain is relatively immature.
0:33:39 > 0:33:46He doesn't have much control over his body and even less ability to make sense of the world around him.
0:33:46 > 0:33:50It will be about eight years before his brain reaches its full size
0:33:50 > 0:33:53and he'll be in his mid-teens before it's properly mature.
0:33:56 > 0:34:03Growing our big brains takes time, and while it's happening, our children need looking after.
0:34:03 > 0:34:07And that has shaped our lives in ways you might not expect.
0:34:26 > 0:34:32To understand how a long childhood growing those big brains has affected our species,
0:34:32 > 0:34:37I've come back to Africa.
0:34:37 > 0:34:41I've come to meet the Hadza tribe in northern Tanzania.
0:34:41 > 0:34:46These are modern people, but living in a similar way to our ancestors,
0:34:46 > 0:34:51and their lifestyle gives us an insight into how we all evolved.
0:34:52 > 0:34:57I want to talk to the women about something which affects all human societies,
0:34:57 > 0:35:01it's a great concern to all of us, and that's childcare.
0:35:01 > 0:35:06Getting enough food to feed everyone takes a long time.
0:35:06 > 0:35:13Looking after young children whose brains are still developing is hard work.
0:35:13 > 0:35:17Nibala has five children and she's got another on the way.
0:35:17 > 0:35:21Nibala, how long did you breastfeed your babies for?
0:35:35 > 0:35:40Yes, I've got a baby who is 11 months old.
0:35:42 > 0:35:44Who is taking care of the baby?
0:35:44 > 0:35:46My husband is taking care of my baby.
0:35:52 > 0:35:56- Who is breastfeeding actually, Nibala, who is breastfeeding? - Oh right, oh.
0:35:56 > 0:36:02Erm, she, I've stopped breastfeeding now, so I breastfed her until seven months,
0:36:02 > 0:36:05and then now she is having a bottle.
0:36:08 > 0:36:13- Will it grow up?- Yes, yes, yes!
0:36:13 > 0:36:15LAUGHTER
0:36:15 > 0:36:18I think she thinks this is very strange.
0:36:18 > 0:36:21And I think, you know, I'm now looking at myself and thinking,
0:36:21 > 0:36:27this must sound really odd, this must sound very unnatural and very, very strange. It is.
0:36:30 > 0:36:35'It's normal for women here to have a baby every two to three years.
0:36:35 > 0:36:39'Feeding the older children while breastfeeding is very difficult without help.
0:36:39 > 0:36:47'For Nibala, the only way she can collect enough food is with help from her mother.
0:36:47 > 0:36:53'As in many human cultures, it's the grandmothers that play a vital role in caring for their grandchildren.'
0:36:53 > 0:36:57How important is their grandmother in providing for your children?
0:37:22 > 0:37:27It's not even eight o'clock and it's already blazing.
0:37:27 > 0:37:30'It's thought that the need to have extra help from older women
0:37:30 > 0:37:33'has actually affected how long we evolved to live for.'
0:37:42 > 0:37:44'Magdalena is in her seventies,
0:37:44 > 0:37:46'and helps to look after five grandchildren.'
0:38:14 > 0:38:19'And Magdalena isn't unusual. Even without modern medicine,
0:38:19 > 0:38:22'many Hadza live well into their 70s.'
0:38:32 > 0:38:39Having grandmothers around like this to help look after and provide for the children
0:38:39 > 0:38:41is such a great advantage,
0:38:41 > 0:38:47and one that may have driven the evolution of our unique life histories,
0:38:47 > 0:38:54where women survive for decades after their reproductive years, after the menopause.
0:38:54 > 0:39:02The fact that women live long past the end of their reproductive years originally baffled scientists.
0:39:02 > 0:39:06But it's now thought that, by living into old age and looking after their grandchildren,
0:39:06 > 0:39:14grandmothers could help their daughters produce lots of children in quick succession.
0:39:14 > 0:39:18By living longer, our species is able to breed more quickly,
0:39:18 > 0:39:21in far greater numbers than any other ape.
0:39:21 > 0:39:28And this population growth has ensured the success of our species.
0:39:28 > 0:39:33Grandmothers and grandfathers would not only pass on important information
0:39:33 > 0:39:38to the younger generation, but by supporting their children and grandchildren,
0:39:38 > 0:39:45they would help the human population to expand, and eventually spread across the globe.
0:39:49 > 0:39:54With their tools, big brains and growing populations,
0:39:54 > 0:39:57successive waves of human species left Africa.
0:39:59 > 0:40:02First Homo erectus, the hand axe maker.
0:40:05 > 0:40:11A million years later, they were followed by another human species, Homo heidelbergensis.
0:40:16 > 0:40:19In Europe, they evolved into the Neanderthals.
0:40:22 > 0:40:26And in Africa, they became us, Homo sapiens.
0:40:28 > 0:40:34And it was from Africa that our species spread out to colonise the world.
0:40:57 > 0:41:01With our large brains, we flourished in new environments.
0:41:02 > 0:41:05But we weren't alone.
0:41:08 > 0:41:13We know from fossils and archaeology that our pioneering ancestors
0:41:13 > 0:41:15weren't heading into virgin territory.
0:41:15 > 0:41:18Around the world, there were other species of humans
0:41:18 > 0:41:21already living there when we arrived.
0:41:23 > 0:41:29In Europe, Homo sapiens were entering the territory of the Neanderthals.
0:41:31 > 0:41:36Neanderthals were a species of human very similar to us.
0:41:36 > 0:41:40They were a physically formidable competitor, heavily built,
0:41:40 > 0:41:44with short limbs adapted for the colder climate.
0:41:44 > 0:41:46They may have been strong,
0:41:46 > 0:41:49but they have developed a reputation for being dim-witted.
0:41:53 > 0:41:59Because within a few thousand years of Homo sapiens arriving in Europe, the Neanderthals,
0:41:59 > 0:42:02like every other human species before, went extinct.
0:42:06 > 0:42:11It's always been thought the reason for our survival was our superior intelligence.
0:42:14 > 0:42:20This is me, this is my skull, which is a perfect specimen, of course, of a modern human,
0:42:20 > 0:42:22and this is a Neanderthal.
0:42:22 > 0:42:26And I hope you'll agree that they look distinctly different,
0:42:26 > 0:42:28especially when we look at the faces.
0:42:28 > 0:42:32The Neanderthal has a massive brow ridge over the eyes,
0:42:32 > 0:42:35and then a sloped-back, a swept-back forehead,
0:42:35 > 0:42:39whereas I've got a very slight brow ridge, if it's there at all,
0:42:39 > 0:42:43and then a very, very steep frontal bone, a steep forehead.
0:42:43 > 0:42:46The faces are very different,
0:42:46 > 0:42:50but there's an overwhelming similarity here,
0:42:50 > 0:42:57and that is in the size of the brain cases. Neanderthals had about the same size brains as us.
0:42:57 > 0:43:00So, if we're going on brain size alone,
0:43:00 > 0:43:06there's nothing to suggest that I should be any cleverer than a Neanderthal.
0:43:08 > 0:43:14So, if Neanderthals and Homo sapiens both had similarly large brains,
0:43:14 > 0:43:18why is it that today there's just us left?
0:43:22 > 0:43:27'At the Max Planck Institute in Leipzig, scientists are trying to understand
0:43:27 > 0:43:30'the secret of our success at a genetic level.'
0:43:34 > 0:43:38'They have achieved what was once thought impossible,
0:43:38 > 0:43:42'by searching for clues within Neanderthal DNA.'
0:43:46 > 0:43:52It's incredible to think that it's possible to extract tiny fragments of DNA
0:43:52 > 0:43:56from the bones of somebody who lived tens of thousands of years ago,
0:43:56 > 0:44:02and then to piece together those fragments to get the genetic code of an extinct human.
0:44:02 > 0:44:09That genome holds clues to the workings of the Neanderthal body and brain.
0:44:13 > 0:44:19Extracting DNA from ancient bones is a painstaking and complex process.
0:44:19 > 0:44:26'Professor Svante Paabo is head of the team trying to compare our DNA with that of the Neanderthals.'
0:44:29 > 0:44:34And what can Neanderthal DNA tell us about me?
0:44:34 > 0:44:38First of all, what it confirms is that we are very close relatives to Neanderthals.
0:44:38 > 0:44:39We share a common origin,
0:44:39 > 0:44:43something like 2, 300,000 years ago.
0:44:43 > 0:44:47Even since then, there have been interactions with Neanderthals,
0:44:47 > 0:44:51there has been interbreeding between Neanderthals and early modern ancestors.
0:44:51 > 0:44:54- So, in part, I'm a Neanderthal?- Yes.
0:44:54 > 0:44:57The Neanderthals are not quite extinct, if you like,
0:44:57 > 0:44:59they live on in some of us a little bit today.
0:45:01 > 0:45:06'As well as showing a degree of interbreeding between us and our cousins,
0:45:06 > 0:45:10'Neanderthal DNA has revealed clues about their brains.
0:45:13 > 0:45:18'The team here has discovered that Neanderthals share with us
0:45:18 > 0:45:25'the exact same form of a gene called FOXP2, which is connected with language.
0:45:26 > 0:45:30'So it's possible they had similar abilities to speak.'
0:45:30 > 0:45:35The scientists in there are combing through the Neanderthal genome,
0:45:35 > 0:45:37the vast majority of which is the same as ours.
0:45:37 > 0:45:42But what's really remarkable, what they're really looking for are those differences,
0:45:42 > 0:45:46so we're learning more about Neanderthals and about what makes us truly unique.
0:45:52 > 0:45:56I think sort of the billion dollar question to me
0:45:56 > 0:46:01over the next 20, 30 years in this field would be to find the genetic background
0:46:01 > 0:46:08for things like why did technology and culture take off in fully modern humans as it has?
0:46:08 > 0:46:12What made it possible for us to colonise the entire planet,
0:46:12 > 0:46:18every speck of land, something that other early forms of humans never did?
0:46:20 > 0:46:24'While the geneticists continue their search for answers,
0:46:24 > 0:46:29'if we want to understand why we're here, and the Neanderthals aren't,
0:46:29 > 0:46:31'we need to go back to where they lived.'
0:46:39 > 0:46:43'I've come to the British colonial outpost of Gibraltar.
0:46:43 > 0:46:48'We know that about 10,000 years after modern humans arrived in Europe,
0:46:48 > 0:46:53'the Neanderthals had disappeared.
0:46:53 > 0:46:56'So was this down to us outsmarting them?'
0:46:59 > 0:47:04We know from the fossils that Neanderthals had brains as big as ours
0:47:04 > 0:47:10and the genetics is now starting to give us glimpses of what that brain might have functioned like,
0:47:10 > 0:47:16so we know that we share a gene with the Neanderthals which is involved in speech.
0:47:16 > 0:47:19But the best chance we have of getting to know the Neanderthals
0:47:19 > 0:47:23and finding out just how similar or different they were to us,
0:47:23 > 0:47:27is by looking at the physical traces of their behaviour.
0:47:30 > 0:47:35Archaeologist Clive Finlayson has been studying the traces of our extinct cousins.
0:47:37 > 0:47:41So do you feel quite close to these people that you're investigating here?
0:47:41 > 0:47:46Very much indeed. They're enigmatic, there are always more questions,
0:47:46 > 0:47:48but you feel you begin to understand them
0:47:48 > 0:47:50when you begin to uncover their way of life.
0:47:57 > 0:48:01'Much of Clive's research has been centred on a site called Gorham's Cave.
0:48:04 > 0:48:07'Today, it's only accessible by sea.'
0:48:07 > 0:48:09Thanks, Darren.
0:48:13 > 0:48:18'This cave has revealed much about the way Neanderthals lived and behaved,
0:48:18 > 0:48:23'compared with the way modern humans were living at the same time.'
0:48:23 > 0:48:28Yeah, it's amazing to stand here and imagine what it must have been like
0:48:28 > 0:48:31when the sea was so much lower and so much further out.
0:48:31 > 0:48:35There were times when the sea would've been all the way down as far as that ship in the distance,
0:48:35 > 0:48:40and all this would have been the landscape, you know, of pine woods and wetlands,
0:48:40 > 0:48:42a little paradise, a little Eden for the Neanderthals.
0:48:44 > 0:48:49'It used to be thought that Neanderthals had a very limited diet, mostly eating big game.
0:48:49 > 0:48:53'But the cave has revealed some surprising finds.'
0:48:55 > 0:48:59- I can show you little bits of marine molluscs. - Yep, little bits of shell.
0:48:59 > 0:49:03The sea never came up here, so they would've been transported.
0:49:03 > 0:49:07And you can see the little flakes of bits of flint, they were transported by people.
0:49:07 > 0:49:11It's clear evidence that Neanderthals were eating marine molluscs,
0:49:11 > 0:49:16- one of these things which is meant to be a speciality of modern humans.- Yeah.
0:49:16 > 0:49:22'Beyond the food waste left behind, the tools they used tell us a lot about their intelligence.'
0:49:24 > 0:49:30This is a typical flake, made by a Neanderthal, multi-purpose, but still got a sharp edge as you can see.
0:49:30 > 0:49:35- It's very sharp.- So, nice for cutting. The modern humans tend to make these sort of blades,
0:49:35 > 0:49:38which are more sort of long and narrower than the flakes.
0:49:38 > 0:49:41Some people made this to be an important distinction
0:49:41 > 0:49:45but it's probably just a different style of doing it.
0:49:45 > 0:49:48So they're using a different tool kit, but they're achieving the same ends?
0:49:48 > 0:49:52The evidence suggests that they're just as intelligent as we were,
0:49:52 > 0:49:55but maybe did things a different way.
0:49:58 > 0:50:04'It's clearly far too simplistic to dismiss Neanderthals as being too stupid to survive.
0:50:09 > 0:50:15'Further back in the cave, Clive has uncovered more evidence of our extinct cousins.'
0:50:15 > 0:50:20So welcome to the real Gorham's Cave.
0:50:20 > 0:50:23- This is it.- Oh, wow!
0:50:23 > 0:50:26Gosh, you've got no idea of the extent of it as you come in.
0:50:26 > 0:50:32- So were the Neanderthals living this deep in the cave?- Absolutely. This was the big surprise.
0:50:32 > 0:50:35It's not a normal thing for Neanderthals to live at the back of caves,
0:50:35 > 0:50:41they didn't like it, but this seems to be a special cave in many ways.
0:50:41 > 0:50:45As you come down this way - be careful because it's been wet -
0:50:45 > 0:50:49it's rained a lot and it's slippery - but if you come along this way,
0:50:49 > 0:50:54this is a huge cavern that goes back 35 metres. Now...
0:50:54 > 0:50:58- Can I get, can I get in past there? - You can get a little bit in, yes, by all means.
0:50:58 > 0:51:02- Get an idea of how deep it is. - So what they had was a large chamber,
0:51:02 > 0:51:04and they're sleeping in there.
0:51:04 > 0:51:07This feels like it would've been a safe place to spend the night.
0:51:07 > 0:51:10It's a perfect choice. These guys knew what they were doing.
0:51:12 > 0:51:16'It's back here that Clive made his most important discovery.'
0:51:16 > 0:51:18- So are you OK there?- Yep, yep.
0:51:18 > 0:51:23- In there, we excavated a half a camp fire...- Yep.
0:51:23 > 0:51:24..made by Neanderthals.
0:51:24 > 0:51:28And we got radiocarbon date to around 28,000 years ago.
0:51:28 > 0:51:32And, to date, it's the last known site, the last place
0:51:32 > 0:51:35where the Neanderthals lived on the planet, is right there.
0:51:47 > 0:51:49This is a really special place, this cave -
0:51:49 > 0:51:52the archaeology here is quite remarkable.
0:51:52 > 0:51:54But it's also very emotive.
0:51:54 > 0:51:56It's quite sad to sit here
0:51:56 > 0:52:02and know that this was one of the last places that the Neanderthals lived in.
0:52:09 > 0:52:15So, if they had brains as big as ours, and were just as clever as us,
0:52:15 > 0:52:20why did Neanderthals die out, while we went on to flourish?
0:52:22 > 0:52:25In the centuries before the Neanderthals' demise,
0:52:25 > 0:52:28there was dramatic climate change across Europe.
0:52:28 > 0:52:32The woodlands that Neanderthals were used to shrank,
0:52:32 > 0:52:37giving way to open landscapes, where modern humans thrived.
0:52:37 > 0:52:44Do you see the eventual demise of the Neanderthals then really being, you know,
0:52:44 > 0:52:49a lot of chance but, but really being down to climate change?
0:52:49 > 0:52:54I think their luck ran out. They were exploiting a kind of environment that needed some trees for cover.
0:52:54 > 0:52:57They were ambush hunters, they got close to their prey.
0:52:57 > 0:53:01But they weren't built to be out on the open plains.
0:53:01 > 0:53:05It just happens that that landscape expanded at the moment
0:53:05 > 0:53:11when those modern humans have come in, and they tracked these resources, so they spread with that environment.
0:53:11 > 0:53:15And, as the modern human population increased,
0:53:15 > 0:53:21the Neanderthal population declined, leaving small, isolated groups.
0:53:21 > 0:53:27Something as simple as a bad winter or a prolonged drought could have easily wiped them out.
0:53:31 > 0:53:37The more we learn about the Neanderthals, the more like us they seem to have been.
0:53:37 > 0:53:43They were just another human population which, like so many others, has died out.
0:53:43 > 0:53:47But, as the Neanderthals were disappearing from Europe,
0:53:47 > 0:53:53something extraordinary was happening amongst the modern human populations who replaced them -
0:53:53 > 0:53:56a huge cultural explosion.
0:53:58 > 0:54:02Over the next 30,000 years,
0:54:02 > 0:54:06we would leave our mark on the world,
0:54:06 > 0:54:10creating wonderful art, and places of worship.
0:54:14 > 0:54:20Inventing farming and engineering to create a new world,
0:54:20 > 0:54:23building civilisations.
0:54:26 > 0:54:30Mapping and exploring the planet,
0:54:30 > 0:54:38we mechanised and urbanised and extended our reach up to the stars.
0:54:46 > 0:54:52In the blink of an evolutionary eye, we have created a world for ourselves
0:54:52 > 0:54:54which has changed beyond recognition.
0:54:57 > 0:55:03There is this great mystery which lies at the heart of human evolution,
0:55:03 > 0:55:06and it has to do with the way we use our brains.
0:55:06 > 0:55:12Because, for tens of thousands of years, our modern human ancestors lived very simple lives
0:55:12 > 0:55:15and made basic tools out of stone and wood.
0:55:15 > 0:55:20And then look at where we are today, at what we can build, and our technology.
0:55:20 > 0:55:27It just seems utterly mind-blowing that we're the same species which made those stone tools.
0:55:32 > 0:55:39It's been suggested that all this cultural change must be linked to a biological change in our brains.
0:55:39 > 0:55:47But the latest thinking suggests it's a product of something far more basic, a simple increase in numbers.
0:55:51 > 0:55:56As populations increase, ideas are passed on to more and more people,
0:55:56 > 0:56:02and there's a greater chance that any inventions, any innovations, will get picked up and will spread.
0:56:02 > 0:56:06The ideas then take on a life of their own, competing with each other,
0:56:06 > 0:56:11improving and proliferating, and that is cultural evolution.
0:56:11 > 0:56:14What's it called? Brain's gone.
0:56:14 > 0:56:21'Over millions of years, our brains evolved to enable us to pass on ideas,
0:56:21 > 0:56:24'to learn from one another.' Oh wow.
0:56:24 > 0:56:27'And to read each other's minds.
0:56:30 > 0:56:34'Combine that with an ability to expand our numbers
0:56:34 > 0:56:40'because we live longer, with grandmothers helping to raise our big-brained children,
0:56:40 > 0:56:46'and what you have is a perfect storm of biological and cultural evolution,
0:56:46 > 0:56:51'that has taken us from making simple stone tools
0:56:51 > 0:56:56'to creating the vast edifices of the modern world.
0:56:58 > 0:57:05'We have evolved to think and behave in ways that have turned out to be incredibly successful.'
0:57:05 > 0:57:10We have an unrivalled ability to co-operate with each other,
0:57:10 > 0:57:15to communicate, to understand what others are thinking and feeling,
0:57:15 > 0:57:18and to generate culture and technology.
0:57:18 > 0:57:20And as our population grew,
0:57:20 > 0:57:28so too did the cumulative effects of people's contributions to society, generation on generation.
0:57:28 > 0:57:33But all of those abilities that make us human, that bring us to where we are today,
0:57:33 > 0:57:40really come down to just one thing, one bit of each of us,
0:57:40 > 0:57:44our amazingly complex and clever brains.
0:58:07 > 0:58:09Subtitling by Red Bee Media Ltd
0:58:09 > 0:58:11E-mail subtitling@bbc.co.uk