0:00:03 > 0:00:07Hello, and welcome back to Prehistoric Autopsy.
0:00:07 > 0:00:10Here, at Glasgow University, we've been piecing together the bodies
0:00:10 > 0:00:14of some of our most iconic ancient relatives.
0:00:14 > 0:00:17Tonight the spotlight is on one of the most famous.
0:00:17 > 0:00:21She's called Lucy and she lived over three million years ago.
0:00:21 > 0:00:26For months we've been painstakingly rebuilding her skeleton.
0:00:27 > 0:00:30Once again, we've consulted international experts
0:00:30 > 0:00:32and used the latest research...
0:00:33 > 0:00:36That's amazing, we've got a very, very different pattern
0:00:36 > 0:00:39- in the way the forces are spreading throughout the bones.- Yeah, yeah.
0:00:41 > 0:00:45Here is an individual still growing its brain
0:00:45 > 0:00:48and still learning from their parents.
0:00:48 > 0:00:51..and we find out if our primate relatives hold any clues
0:00:51 > 0:00:54as to how Lucy might have communicated.
0:00:54 > 0:00:57- There's one here who is going... - HE TUTS
0:00:57 > 0:01:00- This is the lip smacking behaviour. - Friendly?- Yes.
0:01:01 > 0:01:04We're going to find out just how important she was
0:01:04 > 0:01:08on the evolutionary road to becoming human.
0:01:08 > 0:01:11So, let's go inside and get started.
0:01:25 > 0:01:29So far we've met a Neanderthal, La Ferrassie One,
0:01:29 > 0:01:34and a member of the species Homo erectus, Nariokotome Boy.
0:01:34 > 0:01:38Tonight, we're going to use these few bones, here,
0:01:38 > 0:01:41to build one of our early bipedal ancestors.
0:01:41 > 0:01:45In other words, someone who routinely walked upright.
0:01:45 > 0:01:48So, how far have we come? Well, it's been quite a journey.
0:01:48 > 0:01:53We started here in 2012 with us, Homo sapiens,
0:01:53 > 0:01:56the ONLY species of human on the planet.
0:01:56 > 0:01:58But you don't have to go back very far
0:01:58 > 0:02:00to find we were sharing the planet with other species,
0:02:00 > 0:02:04including a Neanderthal like La Ferrassie One.
0:02:04 > 0:02:06We found out that they were good hunters,
0:02:06 > 0:02:10probably had language and, although they eventually died out,
0:02:10 > 0:02:13some of their DNA lives on in many of us.
0:02:13 > 0:02:17Then we travelled further back, 1.5 million years ago,
0:02:17 > 0:02:20to meet Homo erectus.
0:02:20 > 0:02:22He's one of the first humans to look a lot like us.
0:02:22 > 0:02:25He was a good runner with long legs,
0:02:25 > 0:02:28he used tools and he could probably control fire.
0:02:28 > 0:02:31Tonight we are going even further back
0:02:31 > 0:02:34and to do that we are going to have to shrink the scale down
0:02:34 > 0:02:37because the bit we are interested in is round about here,
0:02:37 > 0:02:393.2 million years ago,
0:02:39 > 0:02:44and we're going to meet a female Australopithecus afarensis called Lucy.
0:02:44 > 0:02:46But why did our ancestors leave the trees
0:02:46 > 0:02:51and what did they trade for the ability to walk on two legs?
0:02:51 > 0:02:54To try to get some answers we've got our lab up there, on the balcony,
0:02:54 > 0:02:58where we'll be examining how these ancestors walked.
0:02:59 > 0:03:03And over here is our experimental area
0:03:03 > 0:03:07where we will be putting our ancestor's teeth to the test.
0:03:07 > 0:03:10Paleoartist Viktor Deak and our team of model makers
0:03:10 > 0:03:15have drawn on all this research to help them reconstruct Lucy.
0:03:15 > 0:03:18There's very little of her skeleton to go on
0:03:18 > 0:03:22and the team have spent weeks carefully rebuilding it, bone by bone.
0:03:22 > 0:03:26Along the way we have gained an extraordinary insight
0:03:26 > 0:03:31into how she walked, what she ate and even how she gave birth.
0:03:32 > 0:03:35Lucy's species lived in Eastern Africa
0:03:35 > 0:03:38between three and four million years ago.
0:03:38 > 0:03:42When her skeleton was discovered it transformed our view of human evolution
0:03:42 > 0:03:47and the man who discovered her is Professor Don Johanson.
0:03:47 > 0:03:51He was working out in East Africa in 1973
0:03:51 > 0:03:54when he came across a fossilised bone that eventually led him
0:03:54 > 0:03:58to the skeleton of one of our early bipedal ancestors.
0:04:03 > 0:04:07I caught up with him at Oakland Zoo, in California.
0:04:07 > 0:04:09PRIMATE HOOTING
0:04:09 > 0:04:11- What I saw was that... - I mean, that's not much to go on!
0:04:11 > 0:04:15..sticking out of the ground and I didn't think much of it.
0:04:15 > 0:04:17I looked at it and I tapped it with my sneaker
0:04:17 > 0:04:20and out fell this bone
0:04:20 > 0:04:23but then I walked a couple of feet further and I looked down,
0:04:23 > 0:04:28and found this bone, which is the bottom end of your thigh bone.
0:04:29 > 0:04:34And when I put them together, like that, and looked at it,
0:04:34 > 0:04:38I could see the characteristic angle of the shaft
0:04:38 > 0:04:43- that comes with being a biped, walking upright.- In a straight line?
0:04:43 > 0:04:45In a chimpanzee it would be in a straight line,
0:04:45 > 0:04:47in a baboon it would be a straight line,
0:04:47 > 0:04:50but in a human it's at an angle.
0:04:50 > 0:04:54'This single knee joint had enormous implications.'
0:04:54 > 0:04:55All other primates,
0:04:55 > 0:04:58in fact, all other mammals on the planet, walk on four legs
0:04:58 > 0:05:00and we walk on only two legs.
0:05:00 > 0:05:04So, to be able to find a bone that was,
0:05:04 > 0:05:07that testified to the fact that these creatures,
0:05:07 > 0:05:10these early humans at 3.4 million, was walking upright,
0:05:10 > 0:05:14justified its placement on the human family tree,
0:05:14 > 0:05:16rather than the ape family tree.
0:05:16 > 0:05:20One year later, in 1974, Don returned
0:05:20 > 0:05:22and made an even more remarkable find.
0:05:24 > 0:05:26And a little glint of bone,
0:05:26 > 0:05:28tiny little fragment of bone, caught my eye
0:05:28 > 0:05:32and then I saw a shard of skull and a chunk of mandible,
0:05:32 > 0:05:35and I looked up the slope and I could see other bones eroding out
0:05:35 > 0:05:38and I thought, "My God, this is part of a skeleton!"
0:05:39 > 0:05:41He'd found the most complete skeleton
0:05:41 > 0:05:44of one of our early ancestors.
0:05:44 > 0:05:47It was an extraordinary moment because at that point,
0:05:47 > 0:05:50in terms of the search for human origins,
0:05:50 > 0:05:52anything older than four million years,
0:05:52 > 0:05:55you could put those remains in the palm of your hand.
0:05:55 > 0:05:56There was a single tooth, a fragment of jaw,
0:05:56 > 0:06:01a bit of arm but nothing else. This was really the childhood dream.
0:06:01 > 0:06:03This is the dream I had as a kid.
0:06:03 > 0:06:08Going to Africa, finding a skeleton, finding more than just a bone.
0:06:08 > 0:06:11Don gave the skeleton a name.
0:06:11 > 0:06:14Lucy, why did you call her that?
0:06:14 > 0:06:17Well, I've always been a great fan of The Beatles
0:06:17 > 0:06:20and I had a Beatles tape playing in my little tape recorder,
0:06:20 > 0:06:22and Lucy In The Sky With Diamonds was playing,
0:06:22 > 0:06:24and my girlfriend on the expedition said,
0:06:24 > 0:06:27"Well, if you think it's a female, why don't you call her Lucy?"
0:06:27 > 0:06:30And that's how she got her name.
0:06:30 > 0:06:32Well, what a discovery.
0:06:32 > 0:06:36Tonight, to help us turn those few bones that Don found
0:06:36 > 0:06:39into a life-size reconstruction of Lucy
0:06:39 > 0:06:43we're joined by Professor Carol Ward from the University of Missouri.
0:06:43 > 0:06:46And Carol knows Don and Lucy really well, don't you?
0:06:47 > 0:06:49I do, we've all worked together for many years!
0:06:49 > 0:06:52So, tell us a little bit about her.
0:06:52 > 0:06:55She is the smallest Australopithecus afarensis that we have.
0:06:55 > 0:06:56She is minute.
0:06:56 > 0:06:59How about her age? Any idea on her age?
0:06:59 > 0:07:02Well, we can tell that even though she is small, she was fully adult.
0:07:02 > 0:07:05When you look at the bones and the teeth, you can see signs of age,
0:07:05 > 0:07:07for example, she has her wisdom teeth in.
0:07:07 > 0:07:10So that is about a modern human 20-year-old, or so.
0:07:10 > 0:07:13But on the long bones,
0:07:13 > 0:07:16we can see that her growth plates would have been completely fused up.
0:07:16 > 0:07:17No sign of a growth plate.
0:07:17 > 0:07:19So she wouldn't have gotten any taller.
0:07:19 > 0:07:22That happens when we get to be at the end of our teenage years.
0:07:22 > 0:07:25- So, she is a young adult? - She is a young adult.
0:07:25 > 0:07:28Her teeth weren't too worn down so we know she wasn't very old.
0:07:28 > 0:07:29- Maybe 20 years old or so.- Yeah.
0:07:29 > 0:07:31It is really interesting comparing her with that chimp.
0:07:31 > 0:07:33It is really small. Because if you compare that
0:07:33 > 0:07:35to that upper arm bone of the chimpanzee,
0:07:35 > 0:07:37it is smaller, isn't it?
0:07:37 > 0:07:42Yes. She is tiny, really tiny. But we know that she stood upright.
0:07:42 > 0:07:44So, how tall would she have been?
0:07:44 > 0:07:48About the size of a three-and-a-half-year-old child.
0:07:48 > 0:07:52- So, very, very small. Smaller than that chimp if it stood up.- Yes.
0:07:52 > 0:07:53She is very, very tiny.
0:07:53 > 0:07:57We are comparing her to a chimpanzee
0:07:57 > 0:07:58and there is a good reason for that.
0:07:58 > 0:08:03We know that we share 98.8% of our DNA with a chimpanzee.
0:08:03 > 0:08:07Yes, we are both modern animals. Chimpanzees aren't our ancestors,
0:08:07 > 0:08:10but it is still useful to make these comparisons.
0:08:12 > 0:08:15We share a common ancestor with chimps.
0:08:15 > 0:08:19Around five to seven million years ago we split.
0:08:19 > 0:08:22The ancestors of chimpanzees took one evolutionary path
0:08:22 > 0:08:24and our ancestors took another.
0:08:28 > 0:08:33Around the time of the split much of Africa was covered in dense forest.
0:08:33 > 0:08:35Our closest living relatives
0:08:35 > 0:08:38are still well adapted to this environment.
0:08:38 > 0:08:42When I visited Kibale Forest in Uganda,
0:08:42 > 0:08:44I tried following one of them.
0:08:50 > 0:08:52It looks as though they are moving quite slowly
0:08:52 > 0:08:54but I can assure you they're not!
0:08:54 > 0:08:57This is a fairly fast pace to be moving through the jungle.
0:08:57 > 0:09:01'So, if getting around on all fours is so efficient
0:09:01 > 0:09:05'why did our ancestors begin to walk upright?'
0:09:05 > 0:09:10The answer could lie in the way that the world's climate was changing.
0:09:10 > 0:09:14Around three to four million years ago in Eastern Africa,
0:09:14 > 0:09:16where Lucy's species lived,
0:09:16 > 0:09:20the thick jungle was gradually being replaced by open savanna.
0:09:24 > 0:09:25And it was this changing environment
0:09:25 > 0:09:28that may have contributed to Lucy's species
0:09:28 > 0:09:32spending more and more time on the ground, walking on two legs.
0:09:33 > 0:09:35So, what did she look like?
0:09:35 > 0:09:37Well, these bones are really wonderful.
0:09:37 > 0:09:41They are an incredibly accurate cast of Lucy's skeleton
0:09:41 > 0:09:44and they are the starting point for our reconstruction.
0:09:44 > 0:09:46Viktor is our paleoartist.
0:09:46 > 0:09:50Viktor, there is really not that much to go on with Lucy.
0:09:50 > 0:09:51We have 40% of her skeleton
0:09:51 > 0:09:54but there are lots of missing bits as far as you are concerned.
0:09:54 > 0:09:56So how are you filling it all in?
0:09:56 > 0:09:58What I am doing is,
0:09:58 > 0:10:01because Lucy is similar to humans in some respect, I am using
0:10:01 > 0:10:05a modern human skeleton to help me infer some of the missing pieces.
0:10:05 > 0:10:09I have mirror-imaged certain bones to fill in the gaps.
0:10:09 > 0:10:12Wow! Fantastic. This is just a virtual skeleton
0:10:12 > 0:10:15but a team in America have filled in some of the missing parts
0:10:15 > 0:10:18using other fossils and making a physical model of the skeleton
0:10:18 > 0:10:20which we are going to use
0:10:20 > 0:10:22as the basis for our own reconstruction of Lucy.
0:10:23 > 0:10:26We had a copy of it delivered to our model-makers' workshop
0:10:26 > 0:10:31and I went down to help them put it together.
0:10:31 > 0:10:34Jez Gibson Harris is in charge of the team.
0:10:36 > 0:10:40Cast in plaster, these bones are an exact copy of the originals,
0:10:40 > 0:10:44which are kept under lock and key in Ethiopia.
0:10:44 > 0:10:46So the brown parts are casts of the original fossils.
0:10:46 > 0:10:47So they have been painted
0:10:47 > 0:10:50so that we know that that's what the original fossil was.
0:10:50 > 0:10:52And then the white parts are the reconstruction.
0:10:52 > 0:10:55But that will have been based on other fossils.
0:10:55 > 0:10:59- Isn't it amazing how narrow her jaw is?- It is very small.
0:10:59 > 0:11:01- But the teeth are huge.- Yes.
0:11:01 > 0:11:05All we have to do now is assemble it.
0:11:07 > 0:11:09It is quite nerve-racking
0:11:09 > 0:11:13having got this amazingly accurate cast, to then start drilling into it!
0:11:13 > 0:11:17Everything is hanging off the skull and the spine.
0:11:17 > 0:11:19I just want to check something else,
0:11:19 > 0:11:22which was the angle that these would fit onto the apron.
0:11:22 > 0:11:24This is a very close-fitting joint.
0:11:24 > 0:11:26It is a question of getting that anterior edge,
0:11:26 > 0:11:29the front edge here, matching up.
0:11:29 > 0:11:33- OK.- So it kind of feels right. It locks in.
0:11:33 > 0:11:38'But with important pieces like the rib cage, hands, and feet missing,
0:11:38 > 0:11:41'there are still a lot of questions to answer.'
0:11:43 > 0:11:46Ancient skeletons are often found without hands and feet
0:11:46 > 0:11:49because they are small bones and the first to disappear.
0:11:49 > 0:11:52But luckily there are other ways that we can find out
0:11:52 > 0:11:54how our ancestors walked.
0:11:54 > 0:11:57- And George, you are finding out, up on the balcony.- Absolutely.
0:11:57 > 0:11:59I am up here in the lab
0:11:59 > 0:12:02with Professor Robin Crompton of the University of Liverpool.
0:12:02 > 0:12:05Robin, you are one of the world's experts
0:12:05 > 0:12:08on the bipedalism of afarensis.
0:12:08 > 0:12:09What have we got here?
0:12:09 > 0:12:11What we can see in front of us is a small section
0:12:11 > 0:12:16of a series of footprint trails from the Laetoli area in Tanzania.
0:12:16 > 0:12:21And you can see one small trail representing a young individual.
0:12:21 > 0:12:26And next to it, a larger trail which we think represents two adults,
0:12:26 > 0:12:29with the second adult treading in the footsteps of the first.
0:12:29 > 0:12:32- So it's a family group? - It's a family group.
0:12:32 > 0:12:35And rather nicely, they may have been holding hands.
0:12:35 > 0:12:37How do we know that these footprints
0:12:37 > 0:12:41were made by Australopithecus afarensis?
0:12:41 > 0:12:45To the best of our knowledge there is only one species present at Laetoli
0:12:45 > 0:12:49at 3.65 million years ago, and that is indeed Australopithecus afarensis.
0:12:49 > 0:12:50How did it form?
0:12:50 > 0:12:53There was a nearby volcano called Sadiman
0:12:53 > 0:12:57which occasionally erupted and produced volcanic ash.
0:12:57 > 0:12:59The layers appear to be about 20 centimetres deep.
0:12:59 > 0:13:04And they get wet, the moisture seeps through the ash layer,
0:13:04 > 0:13:06and becomes cemented and rigid,
0:13:06 > 0:13:08so that the footprints can form clearly above it.
0:13:08 > 0:13:13And extra ash from the volcano falls on top, and seals this in time?
0:13:13 > 0:13:15Exactly.
0:13:15 > 0:13:19- How would my footprint compare to these?- Let's have a look.
0:13:19 > 0:13:23I thought you might say that, actually!
0:13:23 > 0:13:26What I'd like you to do is go to the end of this trackway here,
0:13:26 > 0:13:29and, I'm afraid, take your shoes and socks off.
0:13:29 > 0:13:34What we have got is a little short section of sand.
0:13:34 > 0:13:37To get you used to the feel of sand under your feet
0:13:37 > 0:13:39before you tread in the ash layer,
0:13:39 > 0:13:42which is the closest mimic we can produce for the Laetoli deposits.
0:13:42 > 0:13:44That is what you are after?
0:13:44 > 0:13:49A nice, even short stride, with, if possible, both feet in the ash layer.
0:13:49 > 0:13:55Right. I am going to walk as if ambling along a volcanic ash bed.
0:13:55 > 0:14:00There we are. Fantastic. Right, well, you have got two there.
0:14:00 > 0:14:01You've got a left and a right.
0:14:01 > 0:14:05- What happens now? - OK, let's scan them.
0:14:07 > 0:14:10And we put the rather Heath Robinson arrangement on top.
0:14:10 > 0:14:12I like that, it's good.
0:14:12 > 0:14:13Laser scanner.
0:14:16 > 0:14:18And we should be set up.
0:14:18 > 0:14:19And here we go.
0:14:21 > 0:14:23This is really hi-tech stuff.
0:14:23 > 0:14:30That helps you make a completely accurate 3D image of my footprint?
0:14:30 > 0:14:32Absolutely.
0:14:32 > 0:14:34- And here's the image. - There it is!
0:14:34 > 0:14:40Now we do some analysis using other software to bring up the image.
0:14:40 > 0:14:41I hope that's me in the middle.
0:14:41 > 0:14:46That is indeed you in the middle, with a lovely high arch
0:14:46 > 0:14:49- demonstrating you're undoubtedly a human.- And that is afarensis?
0:14:49 > 0:14:50That is afarensis.
0:14:50 > 0:14:53What you're seeing here is the deeper the red,
0:14:53 > 0:14:55the higher the pressure. You can see in particular,
0:14:55 > 0:14:58and most importantly, a large, deeper impression
0:14:58 > 0:15:02under the heel which is absolutely diagnostic of upright walking.
0:15:02 > 0:15:04Excellent.
0:15:04 > 0:15:08And here we have a bonobo, or pygmy chimpanzee.
0:15:08 > 0:15:10Look at the difference.
0:15:10 > 0:15:14Afarensis and me, our big toe is much in line, parallel...
0:15:14 > 0:15:18We've closely adapted, or brought into the other toes.
0:15:18 > 0:15:21They are giving push-off force to the ground
0:15:21 > 0:15:24and there's very little of that in the bonobo.
0:15:26 > 0:15:29The Laetoli footprints show that Lucy, and her kind,
0:15:29 > 0:15:33had traded their opposable big toe for an arched foot like ours
0:15:33 > 0:15:37and were walking upright over three million years ago.
0:15:38 > 0:15:41And that's not all, there were other footprints,
0:15:41 > 0:15:46some from hyenas and even Deinotherium.
0:15:46 > 0:15:50Ancestors of the modern elephant, they were around four metres tall
0:15:50 > 0:15:53and weighed up to 18 tonnes.
0:15:53 > 0:15:58For little Lucy, and her kind, this would have been a dangerous place to walk around in,
0:15:58 > 0:16:01but walk they did.
0:16:01 > 0:16:05Well, it's not just our feet that were changing,
0:16:05 > 0:16:07not just our ancestors' feet that were changing,
0:16:07 > 0:16:10it was other bits of their anatomy as well.
0:16:10 > 0:16:12And we should have some animations coming up.
0:16:12 > 0:16:15Now, this is a human walking along,
0:16:15 > 0:16:19and we can see that we walk with a nice, straight leg.
0:16:19 > 0:16:21And one of the key bits of anatomy is up here,
0:16:21 > 0:16:23these are the abductor muscles on the outside of your hip joint,
0:16:23 > 0:16:28and they stop your hips swinging from side to side as you're walking.
0:16:28 > 0:16:30- Robin, that's a chimp over your end, isn't it?- Yep.
0:16:30 > 0:16:32Completely different gait,
0:16:32 > 0:16:35so that's very bent, very bent hip, bent knee.
0:16:35 > 0:16:37Really, what you can see in the chimpanzee is
0:16:37 > 0:16:41the strong flexure of the knee,
0:16:41 > 0:16:43bringing all the force of the body down behind the knee
0:16:43 > 0:16:45and in front of the foot.
0:16:45 > 0:16:48Now this is continually flexing the knee joint
0:16:48 > 0:16:51and this is what makes that sort of walking so inefficient.
0:16:51 > 0:16:54- That looks very inefficient... - It does, yeah.
0:16:54 > 0:16:57..with this rotating hip. It's very hard to do.
0:16:57 > 0:17:00One of the reasons is if you stand in this sort of posture,
0:17:00 > 0:17:03gravity's continuing to flex your knee
0:17:03 > 0:17:06and your muscles at the front of your thigh work harder and harder
0:17:06 > 0:17:09to stop you bending more and more and it becomes very tiring.
0:17:09 > 0:17:12It's very tiring and your knees start to shake.
0:17:12 > 0:17:16So it's much more efficient to actually straighten your legs.
0:17:16 > 0:17:19- It's more efficient to stand that way and walk this way.- Absolutely.
0:17:19 > 0:17:22- And so who's this in the middle, then?- That's Lucy.
0:17:22 > 0:17:25So this is how Lucy would have walked?
0:17:25 > 0:17:28I would say a little bit more straight-legged than that too.
0:17:28 > 0:17:31- Even more straight-legged? - More straight-legged than that.
0:17:31 > 0:17:33There's a slight swing of the hips, isn't there.
0:17:33 > 0:17:36There's basically a broader hip than we would have had.
0:17:36 > 0:17:38I think we need to emphasise that chimpanzees
0:17:38 > 0:17:42are NOT our ancestors and we're using them as a comparison.
0:17:42 > 0:17:46It seems that what we've got here in Australopithecus afarensis
0:17:46 > 0:17:50is something which is almost halfway between a very chimpanzee-like
0:17:50 > 0:17:53way of walking and a modern human way of walking.
0:17:54 > 0:17:57Well, looking at the anatomy of Lucy's feet,
0:17:57 > 0:18:01knees and pelvis, it suggests she's spending lots of time
0:18:01 > 0:18:02walking on the ground.
0:18:02 > 0:18:06But some new research has been looking at another bit of her anatomy - her hands.
0:18:06 > 0:18:11And this may shed some light on how much she was using THEM for climbing.
0:18:17 > 0:18:21Even though I'm a human and well adapted to walking on the ground,
0:18:21 > 0:18:24I'm still a primate and I can climb pretty well.
0:18:24 > 0:18:28This is quite unapelike this first bit...
0:18:28 > 0:18:29climbing up a ladder.
0:18:31 > 0:18:36There's no doubt that our ancient ancestors spent a lot more time in the trees than we do.
0:18:36 > 0:18:40So when did they decide to trade life in the trees
0:18:40 > 0:18:41for life on the ground?
0:18:43 > 0:18:46Now, I'm really excited by some new research which is looking
0:18:46 > 0:18:49not just at the shape of bones but looking right inside them
0:18:49 > 0:18:53at their detailed architecture and it has the potential
0:18:53 > 0:18:59to give us a new insight as to when our ancestors came out of the trees.
0:19:01 > 0:19:03It seems the way that we use our hands,
0:19:03 > 0:19:07in climbing a tree or gripping a tool
0:19:07 > 0:19:10may be recorded within our wrist bones.
0:19:14 > 0:19:18I've come to Powell Cotton Museum in Kent, where I did work for my PhD.
0:19:20 > 0:19:24It's home to one of the most important primate study centres in the world.
0:19:28 > 0:19:32'I'm meeting paleoanthropologist Professor Gabriele Macho.
0:19:32 > 0:19:36'She's been studying the wrist bones of modern chimpanzees and humans
0:19:36 > 0:19:40'and comparing them with wrist bones from Lucy's species,
0:19:40 > 0:19:42'Australopithecus afarensis.'
0:19:43 > 0:19:46Gabriele, specifically which bones have you been looking at?
0:19:46 > 0:19:49We have been looking at the capitate,
0:19:49 > 0:19:51which is the biggest bone of the wrist,
0:19:51 > 0:19:54and it's sitting right in the middle here
0:19:54 > 0:19:57and it's along the main load transfer from the middle finger
0:19:57 > 0:19:59- to the upper arm.- Right.
0:20:00 > 0:20:04'Gabriele has been putting capitate bones into a CT scanner
0:20:04 > 0:20:08'to reveal the internal structure of trabecular bone.'
0:20:10 > 0:20:14In a little bone like this you get a very complex arrangement
0:20:14 > 0:20:16of trabecular bone.
0:20:16 > 0:20:20And it's no coincidence that it is also called the spongy bone.
0:20:20 > 0:20:24- It looks like a sponge. - Of course, it's completely hard.
0:20:24 > 0:20:27It's amazing when you look at these little tiny bones
0:20:27 > 0:20:29and the complexity of the structure on the inside,
0:20:29 > 0:20:32- all this scaffolding inside them. - Absolutely!
0:20:33 > 0:20:36'Having made CT scans of capitate bones,
0:20:36 > 0:20:39'Gabriele applied the same computer modelling
0:20:39 > 0:20:45'that aircraft manufacturers use to analyse stress on aircraft wings.
0:20:45 > 0:20:48'This showed where the spongy bone had been reinforced
0:20:48 > 0:20:51'to cope with the forces applied to them.'
0:20:52 > 0:20:55The difference between the two bones is quite striking.
0:20:55 > 0:21:00In the chimpanzee you see the red loads travel towards the left side
0:21:00 > 0:21:05- and this is the side where you have your little finger.- Right, OK.
0:21:05 > 0:21:07And in the modern humans, see it quite nicely,
0:21:07 > 0:21:11it is travelling towards the thumb side.
0:21:11 > 0:21:14'So chimps show evidence of reinforcement
0:21:14 > 0:21:16'on the little finger side of this bone
0:21:16 > 0:21:20'because that is where the loading is greatest when they climb trees.
0:21:21 > 0:21:24'But in humans, who use their thumbs far more,
0:21:24 > 0:21:26'the loading is on the thumb side of the bone.'
0:21:28 > 0:21:32That's amazing, so applying these virtual loads we've got a very different pattern
0:21:32 > 0:21:35- in the way the forces are spreading throughout the bone.- Yeah.
0:21:37 > 0:21:41This technique could reveal how much time ancient species
0:21:41 > 0:21:42spent in the trees.
0:21:45 > 0:21:49Next Gabriele looked at capitates from Austraolopithicus afarensis,
0:21:49 > 0:21:52the same species as Lucy.
0:21:52 > 0:21:56She also analysed capitates from another slightly older species,
0:21:56 > 0:21:59Australopithecus anamensis.
0:21:59 > 0:22:02So looking at this anamensis capitate,
0:22:02 > 0:22:07this does look like it's loading on this side, on the little finger side,
0:22:07 > 0:22:10- just like the chimpanzee. - That's correct.
0:22:10 > 0:22:16And in afarensis the loads start to travel towards the thumb's side.
0:22:16 > 0:22:19What does that mean in terms of what these species
0:22:19 > 0:22:22would have been doing with their hands?
0:22:22 > 0:22:24Anamensis probably climbed the tree,
0:22:24 > 0:22:30either for shelter, for protection, sleep, or for feeding purposes.
0:22:30 > 0:22:35By 3.5 million years, when you come to Australopithecus afarensis,
0:22:35 > 0:22:40they were mainly using the terrestrial habitat.
0:22:40 > 0:22:43So what do you think about this wrist bone, then?
0:22:43 > 0:22:46Because that's what we were looking at in the film,
0:22:46 > 0:22:47was this little tiny capitate bone,
0:22:47 > 0:22:51and the differences between the capitate bone,
0:22:51 > 0:22:55which comes from just there in the hand, in afarensis and anamensis.
0:22:55 > 0:22:58What we may be seeing is a process of evolutionary change.
0:22:58 > 0:23:02Not all animals change all body parts at the same rate and time in evolution.
0:23:02 > 0:23:05Do you think we can still say that Lucy's kind
0:23:05 > 0:23:07was spending less time in the trees,
0:23:07 > 0:23:09or do you think it's difficult to argue that
0:23:09 > 0:23:11based on just what we've got in the fossils?
0:23:11 > 0:23:14I think that would be a tough thing to argue right now,
0:23:14 > 0:23:15what we need is more fossils.
0:23:15 > 0:23:17It's really interesting, isn't it?
0:23:17 > 0:23:18We always need more fossils!
0:23:18 > 0:23:21The cry is always, "more fossils"!
0:23:21 > 0:23:26What I find fascinating is, is the way we are talking about this mosaic model of evolution.
0:23:26 > 0:23:28It's not like things all arrive in a package.
0:23:28 > 0:23:31Bits of the body are changing at different times
0:23:31 > 0:23:36and species are adapting bits of themselves to changing environments over time.
0:23:36 > 0:23:39Exactly, and that's partly how we know they're different species.
0:23:39 > 0:23:43They're using the environments in different ways, in different parts of the world.
0:23:43 > 0:23:47Well, there's one bit of Lucy's anatomy that could tell us
0:23:47 > 0:23:50so much more if only we had it - her hands.
0:23:50 > 0:23:53Unfortunately, we've only got a few of her finger bones.
0:23:56 > 0:23:59'So the challenge for our model makers was how to recreate
0:23:59 > 0:24:03'this key part of Lucy's anatomy for our reconstruction.
0:24:04 > 0:24:07'I went down to their workshop to find out how they were getting on.
0:24:09 > 0:24:13'They'd been to America to scan a replica Australopithecus afarensis hand.'
0:24:15 > 0:24:19- Are you Matt?- I am. Nice to meet you, Alice.- Nice to meet you too.
0:24:19 > 0:24:23- So, this is Lucy's hand. - This is it!
0:24:23 > 0:24:26'With this data, designer Matt is able to build a physical model
0:24:26 > 0:24:30'using a process called stereolithography.'
0:24:30 > 0:24:35So this is a very technologically advanced photocopier?
0:24:35 > 0:24:37Yes, well, sort of.
0:24:37 > 0:24:41It's already looking like a hand, it looks fantastic.
0:24:41 > 0:24:46'Four hours and several cups of tea later, the hand is complete.'
0:24:48 > 0:24:51That looks really odd. It looks kind of slimy.
0:24:51 > 0:24:54Well, that's the support material you see in there.
0:24:54 > 0:24:59- That's the stuff you've got to peel away to reveal the model bones inside.- Right, OK.
0:24:59 > 0:25:02- But the actual print of the bones is inside there?- That's right.
0:25:03 > 0:25:08'All that remains now is to carefully remove the bones from the printer
0:25:08 > 0:25:11'and clean off the support material.'
0:25:11 > 0:25:14Right, so hands in here, into the rubber gloves.
0:25:17 > 0:25:18Wow! Oh, my God!
0:25:18 > 0:25:21- Nothing's coming off. - Go a little bit closer.
0:25:23 > 0:25:25It should almost act like a blade.
0:25:25 > 0:25:29Ah, this is so satisfying. Look at that.
0:25:31 > 0:25:34That's lovely, so you can really start to see the detail now.
0:25:36 > 0:25:39That little hand, that's lovely.
0:25:40 > 0:25:44'With both hands finished, we finally have all the elements
0:25:44 > 0:25:46'we need to complete our Lucy skeleton.'
0:25:48 > 0:25:51And here is our finished reconstructed skeleton.
0:25:51 > 0:25:52It's wonderful.
0:25:52 > 0:25:56It's fantastic to see her standing up. It's great.
0:25:56 > 0:25:58- It's lovely. - And she's really tiny.
0:25:58 > 0:26:01I think when you put all the bones together like this
0:26:01 > 0:26:03you suddenly realise how small she really is.
0:26:03 > 0:26:06What always impresses me is how you can reconstruct this
0:26:06 > 0:26:10from just a tiny handful of bones.
0:26:10 > 0:26:12And she's got a quite nice straight leg there,
0:26:12 > 0:26:15- so I think Robin would be happy with that.- Very happy.
0:26:15 > 0:26:19- She's knock-kneed, her knees are right under her centre of gravity. - That's lovely.
0:26:19 > 0:26:22The way the femurs are sloping in towards the knees here.
0:26:22 > 0:26:24And the beautiful curvatures in her spine,
0:26:24 > 0:26:28which is something that only humans have, you never see in apes.
0:26:28 > 0:26:31So why did our ancient ancestors choose to walk upright?
0:26:33 > 0:26:36The forests were retreating and out on the savanna
0:26:36 > 0:26:38they were easy prey.
0:26:39 > 0:26:42Walking meant they could travel further to find food
0:26:42 > 0:26:45and it freed up their hands.
0:26:45 > 0:26:48Walking on two legs clearly has advantages
0:26:48 > 0:26:50but it comes at a price
0:26:50 > 0:26:53and it's one we're still paying today.
0:26:54 > 0:26:57Well, over here we have Professor Karen Rosenberg,
0:26:57 > 0:26:59from the University Of Delaware.
0:26:59 > 0:27:03She's been studying this part of Lucy's anatomy very carefully.
0:27:03 > 0:27:05So this is a modern human pelvis,
0:27:05 > 0:27:09and it's a completely different shape from the chimpanzee.
0:27:09 > 0:27:13It's completely different because of the way that we walk.
0:27:13 > 0:27:16As bipeds we've had to modify our pelvis completely
0:27:16 > 0:27:20in order to walk on two legs, which a chimpanzee doesn't do.
0:27:20 > 0:27:21I mean, this is like a blade.
0:27:21 > 0:27:24- In fact, we do call this the iliac blade, don't we?- Exactly.
0:27:24 > 0:27:27And in us it's formed a kind of basin shape.
0:27:27 > 0:27:29- It's a completely different shape. - Completely different.
0:27:29 > 0:27:32And the birth canal is completely different as well.
0:27:32 > 0:27:36In humans, the birth canal, which is here, is wide at the top,
0:27:36 > 0:27:39and then long at the mid-plane in the middle,
0:27:39 > 0:27:42and then approximately round at the outlet.
0:27:42 > 0:27:45And chimpanzees are long in all dimensions,
0:27:45 > 0:27:51- so it's quite a different shape. - So do chimpanzees have any problems giving birth?
0:27:51 > 0:27:53Apparently not, apparently they have a pretty easy time.
0:27:53 > 0:27:56The baby's head is much smaller than the birth canal
0:27:56 > 0:27:59and it seems to go through in a pretty straightforward way
0:27:59 > 0:28:00without a lot of difficulty.
0:28:00 > 0:28:06So, do you think that the changes to the human pelvis,
0:28:06 > 0:28:09that have come about because of this adaptation to walking on two legs,
0:28:09 > 0:28:12- have had a knock-on effect for childbirth?- Huge effect for childbirth.
0:28:12 > 0:28:14And not just the modifications for locomotion,
0:28:14 > 0:28:17but it's because we give birth to babies with large brains.
0:28:17 > 0:28:21Yeah, that's a bad bit of design, isn't it?
0:28:21 > 0:28:23- A very bad design.- OK.
0:28:23 > 0:28:27So, babies with big brains would have come along a bit later,
0:28:27 > 0:28:29after Lucy's kind, but over here
0:28:29 > 0:28:35we've got a reconstructed Lucy's pelvis. I think it's very useful
0:28:35 > 0:28:39to see the pelvis in the round with the sacrum at the back as well.
0:28:39 > 0:28:40Now, first of all, it's very, very tiny,
0:28:40 > 0:28:43but I think if I put it in the middle there,
0:28:43 > 0:28:46I think that looks more like a modern human pelvis
0:28:46 > 0:28:47than it does like a chimpanzee.
0:28:47 > 0:28:50- It's looks nothing like a chimpanzee pelvis.- Absolutely.
0:28:50 > 0:28:53The modifications that happened because we walk on two legs
0:28:53 > 0:28:57had taken place obviously by the time of Lucy,
0:28:57 > 0:29:00and so the pelvis looks much more similar to a modern human.
0:29:00 > 0:29:02But it doesn't look exactly like a modern human.
0:29:02 > 0:29:06And that's because the birth canal didn't have to give birth
0:29:06 > 0:29:07to a large-brained baby.
0:29:07 > 0:29:10So do you think Lucy would have still been able
0:29:10 > 0:29:13- to give birth relatively easily, then?- Relatively easily,
0:29:13 > 0:29:15but differently than in a chimpanzee.
0:29:15 > 0:29:19How have you been able to work that out and how differently?
0:29:19 > 0:29:21Well, quite differently.
0:29:21 > 0:29:23If we look at the way that modern humans give birth.
0:29:23 > 0:29:25So this is a newborn baby, by the way.
0:29:25 > 0:29:27This is a model of a newborn baby.
0:29:27 > 0:29:30In modern humans, the fit between the baby's head
0:29:30 > 0:29:33and the baby's shoulders and the birth canal is quite tight,
0:29:33 > 0:29:36as lots of people know from personal experience.
0:29:36 > 0:29:39Yes, I know it from personal experience!
0:29:39 > 0:29:42The baby's head typically enters the birth canal facing to the side,
0:29:42 > 0:29:46- like this.- Yeah. - But then it usually gets stuck.
0:29:46 > 0:29:49So it usually turns, rotates, 90 degrees,
0:29:49 > 0:29:52and emerges like this...
0:29:52 > 0:29:55..so the back of the baby's head
0:29:55 > 0:29:58is facing to the front of the mother's body.
0:29:58 > 0:30:01So the mother can't easily reach down and clear
0:30:01 > 0:30:04the baby's breathing passage, or move the umbilical cord if it's around the neck.
0:30:04 > 0:30:06Those are things that, in other animals,
0:30:06 > 0:30:08the mother can do for herself,
0:30:08 > 0:30:10but it's more difficult for humans to do.
0:30:10 > 0:30:14Humans are typically, almost always, born with another person helping.
0:30:14 > 0:30:18So with Lucy's pelvis, then, why do you think it would have been
0:30:18 > 0:30:21difficult to get a baby out through Lucy's pelvis?
0:30:21 > 0:30:24Because her babies would have had much smaller heads than ours.
0:30:24 > 0:30:28Yes, but Lucy's pelvis and Lucy's birth canal in particular
0:30:28 > 0:30:31is different from both modern humans and a chimpanzee.
0:30:31 > 0:30:35It's like a modern human in that it's wide from side to side,
0:30:35 > 0:30:38but then, it has that shape all the way through.
0:30:38 > 0:30:41- So her baby wouldn't have twisted around in the same way?- Exactly.
0:30:41 > 0:30:44And not only didn't need to turn and twist,
0:30:44 > 0:30:45it probably couldn't turn and twist.
0:30:45 > 0:30:47This is really interesting.
0:30:47 > 0:30:51It means that in order to stand and walk upright on two legs,
0:30:51 > 0:30:53Lucy was paying a price.
0:30:53 > 0:30:57She was paying a price in that it made childbirth more difficult.
0:30:57 > 0:30:58Absolutely.
0:30:58 > 0:31:01This is all about babies fitting through birth canals.
0:31:01 > 0:31:03There are things on the outside of the pelvis as well,
0:31:03 > 0:31:05and that's what I want to have a look at next,
0:31:05 > 0:31:07so let's go over and see Viktor,
0:31:07 > 0:31:10who should be putting the muscles on the outside of Lucy's skeleton.
0:31:11 > 0:31:12That's lovely, Viktor.
0:31:12 > 0:31:17Yeah, I mean, she's a strong little female.
0:31:17 > 0:31:18And we're really kind of getting
0:31:18 > 0:31:21an idea of her proportions there as well.
0:31:21 > 0:31:24She's got quite short legs and long arms,
0:31:24 > 0:31:26especially compared to Nariokotome Boy.
0:31:26 > 0:31:30Right, absolutely. Her skeleton shows a lot of virgosities.
0:31:30 > 0:31:32It means that she had strong muscles in certain parts -
0:31:32 > 0:31:35- forearms, shoulders. - And you're reflecting that.
0:31:35 > 0:31:37So she is quite well-muscled, isn't she?
0:31:37 > 0:31:39She's really starting to take shape.
0:31:39 > 0:31:41Imagine her walking along on that volcanic ash
0:31:41 > 0:31:43- in Laetoli and making those footprints.- I know.
0:31:43 > 0:31:46When you're reconstructing this,
0:31:46 > 0:31:49you're not just thinking about the muscles and skin
0:31:49 > 0:31:53and all that, but their lives and what affected them.
0:31:53 > 0:31:56- She's really starting to take shape. That's great, Viktor.- Thank you.
0:31:58 > 0:31:59Down in the model-making workshop,
0:31:59 > 0:32:02the team use Viktor's digital prototype
0:32:02 > 0:32:04as a starting point for the final reconstruction.
0:32:06 > 0:32:10Following his advice, sculptor Reza began to put flesh on the bones.
0:32:10 > 0:32:12She's looking great so far.
0:32:12 > 0:32:13My biggest suggestion might be
0:32:13 > 0:32:16to tone down the thickness of the calves,
0:32:16 > 0:32:18cos you get this from a lot of running,
0:32:18 > 0:32:20and while Lucy definitely had the ability to run,
0:32:20 > 0:32:24- her calves may not have been as developed.- Right.
0:32:24 > 0:32:28However, her thighs would probably still stand to be developed,
0:32:28 > 0:32:31because either climbing and walking, they're going to be strong.
0:32:31 > 0:32:35The gluteus looks good. It's flat and broad,
0:32:35 > 0:32:38really following what the anatomy of the pelvis is showing,
0:32:38 > 0:32:41so you've done a really great job at capturing that.
0:32:41 > 0:32:44It's painstaking work, and Reza's job now
0:32:44 > 0:32:48is to build Lucy from the bottom up before the next stage
0:32:48 > 0:32:51in the model-making process can begin.
0:32:51 > 0:32:54Well, we've discussed her pelvis and childbirth, but until recently,
0:32:54 > 0:32:58there was very little information about afarensis children.
0:32:58 > 0:33:01But all that changed six years ago
0:33:01 > 0:33:04when a dramatic new discovery was announced.
0:33:07 > 0:33:12Found buried beneath the sandstone of Ethiopia's Dikika region
0:33:12 > 0:33:14were the remains of a fossilised child.
0:33:16 > 0:33:18From the same species as Lucy,
0:33:18 > 0:33:21this child was just three years old when she died,
0:33:21 > 0:33:24but lived 3.3 million years ago.
0:33:25 > 0:33:27It's a discovery that's given us
0:33:27 > 0:33:30more information about how Lucy's species moved.
0:33:30 > 0:33:31But more importantly,
0:33:31 > 0:33:36it's cast light on a fundamental aspect of being human - childhood.
0:33:37 > 0:33:41To meet the man who freed this child from her sandstone tomb,
0:33:41 > 0:33:45I've come to the California Academy of Sciences in San Francisco.
0:33:54 > 0:33:58Paleoanthropologist Professor Zeray Alemseged is still
0:33:58 > 0:34:01researching his once-in-a-lifetime discovery.
0:34:02 > 0:34:06Known as Dikika Baby, these exact casts of her tiny bones
0:34:06 > 0:34:11hold clues to the origins of one of our oldest ancestors.
0:34:11 > 0:34:14What makes this find so special?
0:34:14 > 0:34:22This find is simply unprecedented because it has a face.
0:34:22 > 0:34:26When you have a face like this, you are basically looking at a child
0:34:26 > 0:34:28that lived 3.3 million years ago.
0:34:28 > 0:34:31You can actually look straight into her eyes.
0:34:31 > 0:34:32She looks at you too.
0:34:36 > 0:34:40But when this child was found, she looked nothing like this.
0:34:40 > 0:34:44Her entire remains were completely encased in sandstone.
0:34:46 > 0:34:51When found, only this cheekbone was sticking out of the sandstone.
0:34:52 > 0:34:54That is amazing.
0:34:56 > 0:34:59It took Zeray years of painstaking work
0:34:59 > 0:35:02to remove the sandstone rock with a dentist's drill -
0:35:02 > 0:35:04one grain at a time.
0:35:05 > 0:35:08This represents three years of work.
0:35:08 > 0:35:11Three years of work removing sandstone grains,
0:35:11 > 0:35:13a grain at a time?
0:35:13 > 0:35:16A grain at a time, and there is no short cut.
0:35:16 > 0:35:18You can now see the skull,
0:35:18 > 0:35:20you can see the jaw...
0:35:20 > 0:35:22And you can see the spinal column at the back...
0:35:22 > 0:35:23..folded round there.
0:35:23 > 0:35:25..which was almost invisible here.
0:35:27 > 0:35:31Zeray cast copies of the bones at every stage of the process,
0:35:31 > 0:35:34and it took him a total of eight years' labour
0:35:34 > 0:35:37before the final result was revealed.
0:35:39 > 0:35:40What a reward!
0:35:40 > 0:35:43I mean, what an incredible...
0:35:43 > 0:35:44An amazing reward.
0:35:46 > 0:35:49'This skeleton is a far more complete record than Lucy's bones.
0:35:49 > 0:35:52'It's over 60% complete.
0:35:52 > 0:35:55'Among her bones are Dikika Baby's two scapulae,
0:35:55 > 0:35:59'and they have their own evolutionary story.'
0:35:59 > 0:36:04Tell me about the shoulder blade. What does it particularly reveal?
0:36:04 > 0:36:08This shoulder joint is critical in exploring
0:36:08 > 0:36:13the type of movement that this creature was involved in.
0:36:13 > 0:36:17'This is the socket that the arm sits in.
0:36:17 > 0:36:19'In humans it faces sideways.'
0:36:19 > 0:36:21In Dikika,
0:36:21 > 0:36:24we know that it was oriented upwardly,
0:36:24 > 0:36:27like what you see in apes.
0:36:27 > 0:36:30Which means it could hang very easily?
0:36:30 > 0:36:31It could raise its arms, yes.
0:36:34 > 0:36:37But even more important evidence was revealed
0:36:37 > 0:36:39when Zeray examined the skull.
0:36:41 > 0:36:45Three-year-old Dikika Baby's skull was the same size
0:36:45 > 0:36:47as a three-year-old chimp's skull.
0:36:49 > 0:36:53But unlike a chimp, Dikika's brain hadn't finished growing.
0:36:54 > 0:36:58And this is crucial for our evolution as a species.
0:36:59 > 0:37:04Here is an individual from the dawn of humanity, 3.3 million years ago,
0:37:04 > 0:37:09still growing its brain and still learning from the parents -
0:37:09 > 0:37:11the mother, the father, the brother.
0:37:11 > 0:37:15Because their brain is very immature at birth.
0:37:15 > 0:37:20And this is, I think, the earliest known evidence
0:37:20 > 0:37:22for the emergence of childhood,
0:37:22 > 0:37:25which is a unique thing characterising homo sapiens today.
0:37:26 > 0:37:28Quite incredible.
0:37:31 > 0:37:35I have to confess, it was really quite emotional
0:37:35 > 0:37:39looking into that child's face from that far back in time.
0:37:39 > 0:37:43And so much painstaking work going into exposing that fossil as well.
0:37:43 > 0:37:47Such a tiny, delicate fossil that gives us so much information.
0:37:47 > 0:37:51So the gist of this is that Dikika Baby's brain
0:37:51 > 0:37:57is so small that actually she was still a child,
0:37:57 > 0:37:58or this was still a child,
0:37:58 > 0:38:01that there was still some growing to do,
0:38:01 > 0:38:03whereas if she grew at the same rate as chimpanzees,
0:38:03 > 0:38:09then we would have expected that baby to have an adult-size brain.
0:38:09 > 0:38:11Or at least slightly larger, exactly.
0:38:11 > 0:38:14This is an Australopithecus afarensis adult,
0:38:14 > 0:38:17and a chimp adult.
0:38:17 > 0:38:23And the brain is bigger, isn't it, by about 20% in afarensis?
0:38:23 > 0:38:24Very slightly larger.
0:38:24 > 0:38:27It overlaps with chimps, but it's just a little bit bigger.
0:38:27 > 0:38:31And it's really interesting, then, to know that from Dikika Baby,
0:38:31 > 0:38:35that not only is the brain getting bigger in afarensis,
0:38:35 > 0:38:37but it's taking longer to grow as well.
0:38:37 > 0:38:40We may be beginning to see a very slight change
0:38:40 > 0:38:42towards a longer childhood.
0:38:42 > 0:38:43But it's only very slight.
0:38:43 > 0:38:48OK, so even if it is only slight, what are the implications of that?
0:38:48 > 0:38:50Well, the reason we have long childhoods is that it takes
0:38:50 > 0:38:52a long time to learn to be a grown-up.
0:38:52 > 0:38:54Kids take a long time to learn from their parents,
0:38:54 > 0:38:56and that's what the long childhood is about.
0:38:56 > 0:38:59If we're beginning to see that in early hominids,
0:38:59 > 0:39:01that may be the start of becoming human in a way.
0:39:01 > 0:39:04And it's very interesting that we may begin to see
0:39:04 > 0:39:07little tiny hints of that in Australopithecus.
0:39:07 > 0:39:09Unfortunately, there's so much about our ancestors
0:39:09 > 0:39:12that doesn't fossilise, like learning and language.
0:39:12 > 0:39:16But there is another important line of evidence that we can turn to,
0:39:16 > 0:39:18and that is looking at living primates.
0:39:18 > 0:39:22I've been to find out about a new research project
0:39:22 > 0:39:25in its infancy that's looking into just that.
0:39:28 > 0:39:31Language is a key part of what it means to be human.
0:39:31 > 0:39:34So how did our ancestors communicate with each other
0:39:34 > 0:39:37before they could speak like we do today?
0:39:37 > 0:39:39It may be possible to find some clues
0:39:39 > 0:39:42by looking at the way primates communicate.
0:39:45 > 0:39:47Supervising a study doing just that
0:39:47 > 0:39:50is evolutionary psychologist Dr Bridget Waller
0:39:50 > 0:39:53from the University of Portsmouth.
0:39:54 > 0:39:57So you look at all the living primates nowadays,
0:39:57 > 0:40:00they are all using very similar facial expressions -
0:40:00 > 0:40:02so we can be very confident if you try and reconstruct
0:40:02 > 0:40:04the behaviour of extinct hominid species
0:40:04 > 0:40:07that they would have used very similar-looking facial expressions -
0:40:07 > 0:40:10things that look a bit like smiling, look a bit like laughing.
0:40:10 > 0:40:13Some things are a little more confusing, like frowning,
0:40:13 > 0:40:15but lots of them would look very, very similar.
0:40:17 > 0:40:20It's an intriguing idea, and in Hampshire,
0:40:20 > 0:40:23a new research project is putting this theory to the test.
0:40:24 > 0:40:28Marwell Wildlife Park is home to the world's first centre
0:40:28 > 0:40:33specialising in the study of this remarkable creature -
0:40:33 > 0:40:36the rare Sulawesi crested macaque.
0:40:37 > 0:40:40Here, Bridget's colleague Jerome Micheletta
0:40:40 > 0:40:44is six months into a long-term research project
0:40:44 > 0:40:46working with the macaques.
0:40:46 > 0:40:49What exactly are you trying to find out about them?
0:40:49 > 0:40:53What I'm interested in is their communicative ability in general,
0:40:53 > 0:40:57so that includes vocalisation, facial expressions and gestures.
0:40:57 > 0:41:00And I'm interested in how they combine all these things
0:41:00 > 0:41:02to communicate in their daily social life.
0:41:04 > 0:41:08Ultimately, Jerome wants to quantify the range of facial expressions
0:41:08 > 0:41:10that these macaques use.
0:41:10 > 0:41:12There's one here who is going...
0:41:12 > 0:41:14SMACKS LIPS
0:41:14 > 0:41:16- The lip smacking behaviour. - Friendly.- Yes.
0:41:16 > 0:41:20He's designed an experiment to measure the macaques' abilities
0:41:20 > 0:41:23to communicate non-verbally.
0:41:23 > 0:41:25Here is how the experiment works.
0:41:25 > 0:41:28On this touch screen here, which the macaques have access to,
0:41:28 > 0:41:30appears a picture of a macaque.
0:41:30 > 0:41:32If they want to play the game,
0:41:32 > 0:41:35they touch the screen three times.
0:41:35 > 0:41:36Two other pictures appear.
0:41:36 > 0:41:38One exactly matches the first,
0:41:38 > 0:41:41the second one isn't the same at all.
0:41:41 > 0:41:44If they press the image that matches the first one...
0:41:44 > 0:41:47- MACHINE BLEEPS - ..they get a bing and they get a treat.
0:41:49 > 0:41:51If they choose the wrong image...
0:41:51 > 0:41:53QUIET BEEP
0:41:53 > 0:41:55..they get a "bloop" sound and they don't get any reward,
0:41:55 > 0:42:00and they have to wait longer for the screen to restart.
0:42:03 > 0:42:05So far, they're not doing too badly.
0:42:07 > 0:42:08So, he's got the majority correct.
0:42:08 > 0:42:10I think so, yeah.
0:42:10 > 0:42:12MACHINE BLEEPS
0:42:13 > 0:42:16On average, how successful are they?
0:42:16 > 0:42:20At the moment, they are around 70% of success.
0:42:21 > 0:42:26That's impressive, but this is only the first phase of the research.
0:42:26 > 0:42:31The next step is to get the macaques to match facial expressions
0:42:31 > 0:42:33and eventually for Jerome to be able to work out
0:42:33 > 0:42:37what those expressions mean.
0:42:38 > 0:42:40A recent study of rhesus monkeys showed
0:42:40 > 0:42:44they distinguish up to a dozen different expressions.
0:42:44 > 0:42:47Jerome thinks macaques might recognise even more.
0:42:49 > 0:42:51So how important could facial expressions have been
0:42:51 > 0:42:55to Lucy's species three million years ago?
0:42:55 > 0:42:58Lucy would have lived in a certain group structure.
0:42:58 > 0:43:01She would have been in a group with lots of females,
0:43:01 > 0:43:03possibly one or more males,
0:43:03 > 0:43:07and so that tells us that they would have needed to communicate
0:43:07 > 0:43:09in order to live in such a structure.
0:43:09 > 0:43:11They would have needed to use their faces,
0:43:11 > 0:43:14would have needed to use non-verbal behaviour
0:43:14 > 0:43:16in order to solidify the communication
0:43:16 > 0:43:17and the social interactions
0:43:17 > 0:43:19that they would have had with each other.
0:43:20 > 0:43:24By looking at the behaviour of modern-day primates,
0:43:24 > 0:43:26new research like this is beginning to shed light
0:43:26 > 0:43:29on how language might have evolved.
0:43:29 > 0:43:35Perhaps Lucy communicated with her group just like these macaques.
0:43:35 > 0:43:37So, if you can't talk, it's all about how you look.
0:43:37 > 0:43:39It is interesting, isn't it,
0:43:39 > 0:43:41that there are all these complex facial expressions
0:43:41 > 0:43:43that primates are using very generally
0:43:43 > 0:43:45to communicate with each other.
0:43:45 > 0:43:47Primates are such social animals,
0:43:47 > 0:43:49and that's where we got it all from too.
0:43:49 > 0:43:52We use everything we can to communicate with one another.
0:43:52 > 0:43:55And it even looks as though chimpanzees smile.
0:43:55 > 0:43:58I think the latest research shows that the bared teeth grin
0:43:58 > 0:44:01of chimpanzees is actually equivalent to human smiling.
0:44:01 > 0:44:04They do. They smile, they effectively laugh,
0:44:04 > 0:44:06they communicate with looks and gestures all the time.
0:44:06 > 0:44:09There's so much more than making sounds to communication.
0:44:09 > 0:44:13Non-visual communication is really prevalent among primates.
0:44:14 > 0:44:17We've discovered a lot about Lucy's species.
0:44:18 > 0:44:22We know they had been walking on two legs for some time.
0:44:23 > 0:44:26This was probably as a result of the changing climate
0:44:26 > 0:44:30and the need to adapt to different environments.
0:44:30 > 0:44:34The price they paid was a more difficult childbirth.
0:44:34 > 0:44:37But it's not just about walking upright.
0:44:37 > 0:44:40In terms of survival, the ability
0:44:40 > 0:44:44to eat a variety of foods is a big evolutionary advantage.
0:44:44 > 0:44:46And thanks to a new scientific technique,
0:44:46 > 0:44:50we may be able to say what Lucy and her species were eating.
0:44:50 > 0:44:53This is Dr Paul Constantino,
0:44:53 > 0:44:57and he's a biological anthropologist from Marshall University in the US.
0:44:57 > 0:45:02Paul, what can you tell about Lucy by just looking at her teeth?
0:45:02 > 0:45:06There are a few different techniques that researchers have developed over the years,
0:45:06 > 0:45:08but one that my colleagues and I have developed lately
0:45:08 > 0:45:12is extracting information about diet and bite force from chips in teeth.
0:45:12 > 0:45:17What does this machine do and how can it help us understand what's happening with teeth wear?
0:45:17 > 0:45:20I'm going to crank down on this handle here
0:45:20 > 0:45:22and what that's going to do, you can see a human molar tooth
0:45:22 > 0:45:26loaded there, and just above it is an indenter.
0:45:26 > 0:45:29- You can also see that on this image over here.- That's a hard object.
0:45:29 > 0:45:34- Exactly.- It's going to bear down on the tooth.- Exactly.
0:45:34 > 0:45:35It's simulating a large, hard object.
0:45:35 > 0:45:38We've loaded it near the cusp of the tooth, near the edge,
0:45:38 > 0:45:40so that it will create a chip.
0:45:40 > 0:45:42- OK.- Shall we have a go? - Absolutely, yeah.
0:45:42 > 0:45:46- We should put on our safety glasses just in case.- Is it that hazardous?
0:45:46 > 0:45:49Every once in a while, a chip will fly across the room.
0:45:49 > 0:45:52- 99% of the time, it just drops to the side.- OK. Right.
0:45:54 > 0:45:57So here you go, applying the force.
0:45:57 > 0:46:00First I have to tell the computer to acquire the data and start reading.
0:46:00 > 0:46:01Now we can see that graph.
0:46:05 > 0:46:09And there it goes, that's going to be a small chip, but you can see,
0:46:09 > 0:46:12here's where the force was being loaded onto the tooth.
0:46:12 > 0:46:15- And then it dropped.- Then it drops off because a chip has pulled away
0:46:15 > 0:46:18from the side of the tooth and...
0:46:18 > 0:46:20So we should be able to see a small fragment.
0:46:20 > 0:46:22Yes, I just have to unload it a bit.
0:46:22 > 0:46:25That's quite a large fragment of tooth!
0:46:25 > 0:46:27Actually, it is quite a large fragment.
0:46:27 > 0:46:30That's sheared off the whole of that edge there.
0:46:30 > 0:46:32It was loaded so close to the edge of the tooth
0:46:32 > 0:46:35that it took a big portion off without that much force, actually.
0:46:35 > 0:46:38That would be something that might happen
0:46:38 > 0:46:41if you'd chewed down a really hard object.
0:46:41 > 0:46:45- Like an olive stone or something. - Exactly.
0:46:45 > 0:46:47We chip our teeth all the time, actually.
0:46:47 > 0:46:49It turns out hominins did as well.
0:46:49 > 0:46:52Here's a maxilla of Australopithecus afarensis, Lucy's species,
0:46:52 > 0:46:56and you can see at least three different chips in these teeth.
0:46:56 > 0:46:59- This one is quite enormous. - That's a huge one there.
0:46:59 > 0:47:01- That's a massive great chunk.- It is.
0:47:01 > 0:47:04And what can this research actually tell us
0:47:04 > 0:47:08about what afarensis and her kind were eating?
0:47:08 > 0:47:11The interesting thing about this research is that
0:47:11 > 0:47:15we've been able to, through several of these experiments,
0:47:15 > 0:47:18plot the force that's required to create a chip
0:47:18 > 0:47:20versus the size of the chip itself.
0:47:20 > 0:47:23What we've learned is that it's a nice linear relationship.
0:47:23 > 0:47:26So what this means is that we can look at chips in the teeth
0:47:26 > 0:47:30of Australopithecus afarensis in this instance
0:47:30 > 0:47:32and just measure that chip and get an estimate of the bite force
0:47:32 > 0:47:34the animal was using when it created that chip.
0:47:34 > 0:47:39And that shows that they were actually able to access
0:47:39 > 0:47:42a wide range of foodstuffs, soft and hard.
0:47:42 > 0:47:45In afarensis' case, they were probably able to access things
0:47:45 > 0:47:48that chimpanzees, for instance, or ancestors of chimpanzees, weren't.
0:47:48 > 0:47:53So, if you were able to access a wide range of foods, harder foods,
0:47:53 > 0:47:58that other things perhaps can't, that makes you much more adaptable and able to survive.
0:47:58 > 0:48:01Animals that can generate a lot of bite force generally don't
0:48:01 > 0:48:04specialise just on harder, tough foods, but they expand
0:48:04 > 0:48:07the breadth of their diets so they still eat the same food as everybody else,
0:48:07 > 0:48:10but now they can access some certain hard nuts and seeds
0:48:10 > 0:48:15which can be quite nutritious, or even things like underground storage organs like tubers,
0:48:15 > 0:48:19which may not be super nutritious, but they can get you through tough times when other food is scarce.
0:48:19 > 0:48:21That is very interesting.
0:48:21 > 0:48:24But there's something even more intriguing about her diet.
0:48:24 > 0:48:28Was she using tools to access those kinds of food?
0:48:30 > 0:48:33Chimps use twigs as tools to dig out termites,
0:48:33 > 0:48:35but their fingers lack the precision grip of humans.
0:48:38 > 0:48:41But was Lucy gripping and using tools more like us?
0:48:42 > 0:48:47It's controversial, but animal bones unearthed in Ethiopia,
0:48:47 > 0:48:52in the same region as Dikika Baby was found, may hold a clue.
0:48:54 > 0:48:57Back at the California Academy of Sciences,
0:48:57 > 0:49:00Professor Alemseged showed me the evidence.
0:49:01 > 0:49:02So, what have we got here?
0:49:02 > 0:49:06This is a bone from an animal
0:49:06 > 0:49:11that lived over 3.4 million years ago.
0:49:11 > 0:49:17And comes from a site which is only 200 metres away from where the Dikika child was found.
0:49:17 > 0:49:19What makes it so special?
0:49:19 > 0:49:22What's special is marks that were induced
0:49:22 > 0:49:27when early hominins were wielding stone tools,
0:49:27 > 0:49:29removing meat off the bone
0:49:29 > 0:49:33and maybe pounding on the bones to access the bone marrow.
0:49:33 > 0:49:36Therefore this is the earliest evidence for tool use.
0:49:36 > 0:49:42'This looks convincing, but what's the scientific evidence?'
0:49:42 > 0:49:46What we did is we mapped the chemical composition of the bone,
0:49:46 > 0:49:49in the marks and out of the marks.
0:49:49 > 0:49:52And when we did that, the part that is not marked
0:49:52 > 0:49:55was very rich in calcium and phosphorus,
0:49:55 > 0:49:57- which is what you expect for bones.- Yeah.
0:49:57 > 0:50:00Whereas when we mapped in the marks themselves,
0:50:00 > 0:50:04we found a small crystal, a rock fragment, that must have been
0:50:04 > 0:50:10dislodged from the tool that was wielded to induce these marks.
0:50:10 > 0:50:15And the way we know that is that the chemical composition of that rock
0:50:15 > 0:50:20was very similar to what you encounter in igneous rocks.
0:50:20 > 0:50:24And of course if you were attempting to use a tool to cut off meat,
0:50:24 > 0:50:26you would not use a soft rock,
0:50:26 > 0:50:28you would pick the hardest rock around, an igneous rock...
0:50:28 > 0:50:30There's evidence of that rock right in the cut.
0:50:30 > 0:50:32That's it.
0:50:32 > 0:50:36It's as if the hominins were kind enough to leave evidence to tell us,
0:50:36 > 0:50:39"By the way, we were using this tool.
0:50:39 > 0:50:43- "If you can't recognise us, here's the evidence."- I'm convinced. - Thank you.
0:50:44 > 0:50:48He was really passionate about it and the marks seem
0:50:48 > 0:50:51so exactly parallel and the bits of rock inside.
0:50:51 > 0:50:55- I was sort of convinced of that. - I'm a bit more sceptical.
0:50:55 > 0:50:56How about you, Carol?
0:50:56 > 0:51:00Whether it's convincing evidence or not, I think it's fairly good.
0:51:00 > 0:51:02The fact that these guys were using and making tools
0:51:02 > 0:51:05shouldn't really surprise us too much because after all,
0:51:05 > 0:51:10chimpanzees use and make tools today, even orang-utans use them for all kinds of purposes.
0:51:10 > 0:51:14We probably shouldn't be too surprised if Lucy and her relatives were using tools, too.
0:51:14 > 0:51:19Why are you sceptical? Why... Because, you know.
0:51:19 > 0:51:22I'm sceptical because other researchers have looked at that evidence
0:51:22 > 0:51:29and they've said, come on, actually, this bone was lying in ground which had lots of stones within it
0:51:29 > 0:51:33and actually, those marks could have been caused by trampling.
0:51:33 > 0:51:37So, OK, yeah, they're effectively the mark of a stone on a bone,
0:51:37 > 0:51:41but that could have got there by a trampling where that stone
0:51:41 > 0:51:44has effectively been driven into the bone.
0:51:44 > 0:51:47But the section of the cuts is like that,
0:51:47 > 0:51:50as if you've dragged something across the bone.
0:51:50 > 0:51:53Yeah. I think it's up for debate at the moment.
0:51:53 > 0:51:58Some people believe it and some people think you could see the same thing from trampling.
0:51:58 > 0:52:00But I think Carol's hit the nail on the head.
0:52:00 > 0:52:03Chimpanzees make and use tools so why on earth wouldn't
0:52:03 > 0:52:06we expect Australopithecus afarensis to have been doing the same thing?
0:52:06 > 0:52:10I think, as we'll see more and more people going into the field and finding evidence of using tools,
0:52:10 > 0:52:13if they're really using them, we're going to find more evidence of it.
0:52:15 > 0:52:18With only a couple of bones to go on, these marks need to be
0:52:18 > 0:52:22treated with caution, but it's an intriguing discovery.
0:52:22 > 0:52:25Now, our reconstruction of Lucy is nearly finished.
0:52:25 > 0:52:30The finer details have to be honed with a mixture of deduction and intuition.
0:52:30 > 0:52:33Let's catch up with Viktor. How are you doing?
0:52:33 > 0:52:38Yeah, I would love to show her to you right now, but I've got to hold off for a minute.
0:52:38 > 0:52:39You are showing me her back.
0:52:39 > 0:52:43Well, you know, what you're seeing here may look different than many
0:52:43 > 0:52:46Australopithecus afarensis you've seen, but what's great about working in this nature
0:52:46 > 0:52:50is that it gives you the ability to test out different looks,
0:52:50 > 0:52:54different hair and different skin colour, before you commit.
0:52:54 > 0:52:57So the science gives you the kind of range of possibilities
0:52:57 > 0:53:01- that then as an artist you can choose where you're sitting within that. - Precisely.
0:53:01 > 0:53:03There's all these decisions at the end,
0:53:03 > 0:53:06- like choosing what her eyes are going to be like.- Sure.
0:53:06 > 0:53:10We can talk about it before we go to the final thing to make that decision.
0:53:10 > 0:53:13We can all be in agreement before a hair is punched.
0:53:13 > 0:53:16- I just want her to look at me. She's looking fantastic. - She will, thank you.
0:53:20 > 0:53:22So our reconstruction is almost complete
0:53:22 > 0:53:24and now that the muscles are finished,
0:53:24 > 0:53:27the model-making team can focus on the next stage in the process.
0:53:27 > 0:53:29It's in the bag.
0:53:29 > 0:53:32Viktor has flown over with Lucy's head,
0:53:32 > 0:53:35which he made at his workshop in New York.
0:53:35 > 0:53:38There are some important decisions to be made
0:53:38 > 0:53:41that will have a big impact on how she will look when she's finished.
0:53:42 > 0:53:46It's interesting thinking about afarensis and eyes.
0:53:46 > 0:53:48They are apes, they are bipedal apes,
0:53:48 > 0:53:51but what's interesting is when you look at chimpanzee eyes,
0:53:51 > 0:53:55the sclera, the whites of the eyes, aren't that pronounced.
0:53:55 > 0:53:57They can be earlier on.
0:53:57 > 0:54:01The colouration in the iris tends to sort of bleed out over time.
0:54:01 > 0:54:05When you look at certain gorillas, mountain gorillas,
0:54:05 > 0:54:07they have very human-looking eyes.
0:54:07 > 0:54:12So I think any route you take is going to be fine.
0:54:12 > 0:54:15However, one is going to give you
0:54:15 > 0:54:17a slightly more human appearance to her face
0:54:17 > 0:54:19and this one's going to give her
0:54:19 > 0:54:23a slightly more ape-ish look to her face.
0:54:25 > 0:54:26With the final decisions made,
0:54:26 > 0:54:29the model-makers can put the finishing touches to Lucy
0:54:29 > 0:54:32before revealing her to us for the first time.
0:54:33 > 0:54:37So we're coming to the end of our incredible time here.
0:54:37 > 0:54:40We began with just us, Homo sapiens,
0:54:40 > 0:54:43and then we started with fragments of skeletons
0:54:43 > 0:54:48and pieced together the bodies of three of our most iconic ancestors
0:54:48 > 0:54:51in extraordinary anatomical detail.
0:54:51 > 0:54:57First we met a Neanderthal, La Ferrassie 1, from 70,000 years ago.
0:54:57 > 0:55:00Each night we've travelled further and further back,
0:55:00 > 0:55:03deep into our evolutionary past.
0:55:03 > 0:55:06At 1.5 million years ago, we met Nariokotome Boy
0:55:06 > 0:55:10from the species Homo erectus, one of the earliest humans.
0:55:10 > 0:55:15And now we've arrived back 3.2 million years ago
0:55:15 > 0:55:20to meet Lucy, from the species Australopithecus afarensis.
0:55:20 > 0:55:23- Viktor, please can we unveil her? - Guys, everybody.- I'm so excited.
0:55:23 > 0:55:25I thought you would never ask!
0:55:25 > 0:55:28- Come and have a look.- It's time. I'm feeling a bit emotional.- Me too.
0:55:28 > 0:55:32- I bet you are.- I can't wait to see what she looks like.
0:55:32 > 0:55:35- Everybody ready?- Yeah.- Right.
0:55:35 > 0:55:37One...two...three.
0:55:40 > 0:55:43- Wow!- She's so little. - She's so sweet!
0:55:43 > 0:55:46- That's amazing.- Isn't she lovely?
0:55:47 > 0:55:51- She really is.- Look at this little person from three million years ago.
0:55:51 > 0:55:54- Incredible. - Those hands are just wonderful.
0:55:54 > 0:55:56Really beautiful.
0:55:56 > 0:55:58She could have held a stone flake,
0:55:58 > 0:56:00she could have made stone tools, possibly.
0:56:00 > 0:56:02Even though the hands are bigger than ours are, perhaps,
0:56:02 > 0:56:06they're shaped so human-like and so in proportion that it's really astonishing.
0:56:06 > 0:56:09And she's only just entering adulthood,
0:56:09 > 0:56:12but presumably she could have already had children.
0:56:12 > 0:56:15Just about now, yeah. About the time she died, absolutely.
0:56:15 > 0:56:17Robin, the feet are so human-like.
0:56:17 > 0:56:21Those prints now come alive for me
0:56:21 > 0:56:24and you can see a couple with a child walking across that ash.
0:56:24 > 0:56:28Very nice little story about that because the small individual
0:56:28 > 0:56:32actually speeds up at the end of the trail to match...
0:56:32 > 0:56:35- He's lagging behind. - Exactly. It's true.
0:56:35 > 0:56:39The stride length changes to match the two adults.
0:56:39 > 0:56:40- Saying, "Come on, keep up!"- Yeah.
0:56:42 > 0:56:47And the jaw. You can't see the teeth.
0:56:47 > 0:56:50That's the one thing that to me looks a bit more chimp-like.
0:56:50 > 0:56:54You can see she's quite prognathic, her face sticks forward quite a bit.
0:56:54 > 0:56:57This is obviously different from modern humans,
0:56:57 > 0:57:00where our jaws have become quite retracted.
0:57:00 > 0:57:01She's fantastic.
0:57:01 > 0:57:05By piecing together how these three moved and how they looked
0:57:05 > 0:57:07and how similar they were to us today,
0:57:07 > 0:57:11I think we've gained a better understanding of not only our family history,
0:57:11 > 0:57:14but what it means to be human.
0:57:14 > 0:57:16Thanks to everyone here and all the experts
0:57:16 > 0:57:21who've helped put flesh on the bones of our three ancient ancestors.
0:57:21 > 0:57:23And thank you at home for joining us here
0:57:23 > 0:57:28on this four-million-year journey back into our past.
0:57:28 > 0:57:30- Goodnight.- Goodnight.