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Stefanus
12th September 2011, 18:41
Missing Link?

Date: 11 April 2010
Producer: Carol Albertyn Christie
Presenter: Bongani Bingwa
Show: Carte Blanche (http://beta.mnet.co.za/carteblanche/Article.aspx?Id=3906&ShowId=1)

http://www.wendag.com/Documente/flash/MN_Carte_20100411_1_1_MissingLink_300K.flv http://www.wendag.com/Documente/flash/MN_Carte_20100411_1_2_MissingLink_1_300K.flv
On Thursday last week the world learned of one of the most significant paleoanthropological discoveries to date, the fossils of a new hominid species that lived almost two million years ago. The find is set to rewrite our history books because it may just help answer that seemingly impenetrable secret - where did we come from?

The latest find at the Cradle of Mankind in the Magaliesburg was of two complete skeletons and they are arguably among the most extraordinary in evolutionary science.

They are being kept under tight security at Wits Institute for Human Evolution.

Prof Lee Berger (Paleoanthropologist): 'And this is arguable the most complete early human ancestor skull ever discovered. You can see he is in almost perfect condition, 1.9-million years old, and it is the type specimen of the new species Australopithecus sediba.'

Sediba is Sotho for 'natural spring' and it is believed that this may have been the point from which the genus Homo arose.

Just over 18 months ago, Prof Lee Berger, a paleoanthropologist at Wits University, and his son Matthew, and their dog, aptly named Tau, were walking in the veldt in the Cradle of Mankind. Lee was charting all the known caves in the area on Google Earth. But they stumbled on something that would fundamentally change the way we view human evolution.

Prof Berger: 'And I reached a point right about here when I realised there was indeed a de-roofed cave here. And I could start seeing blocks. And I reached a point right here, which I will never forget, that spot right there. And there was a rock sitting there with an antelope humerus in it. And I knelt down and looked at it and then I looked around and realised there were lots of blocks and realised that this is a fossil site.'

The submerged cave was blasted open about 100 years ago by limestone miners. Luckily there wasn't enough lime for them to mine, and they abandoned the site with rocks strewn about.

Lee Berger told Matthew, who seems to be following in his father's footsteps, to go ahead and hunt for fossils.

Prof Berger: 'He goes off into the high grass and he went right over to that tree. You see that hollow tree?'

Bongani Bingwa (Carte Blanche presenter): 'Ja.'

Prof Lee Berger' 'He went right over in that direction.'

Matthew Berger: 'I just thought we were going to find just some small antelope fossils and then I walked off to the side and picked up a rock.'

Matthew found a bone sticking out of the rock and called to his father.

Bongani: 'So when you gave it to your dad, and you saw his reaction, what did you think?'

Matthew: 'I was like, 'What is it?' because he hadn't told me yet. He was just swearing when he was approaching me. So he said it was a hominid and I just couldn't believe it.'

Prof Berger: 'I couldn't believe it. I mean, it's what I did my PhD on. You know, to see something so rare - it's the first fossil - and something that I would be one of the few dozens of people who would probably be really qualified to identify that. An extraordinary moment.'

The bone he had found was the clavicle of a young male hominid, probably the same age as Matthew.

Prof Berger: 'I was stunned. I was even more stunned when I turned the block over and on the back of it was a canine and a mandible of a hominid and I knew that maybe we were dealing with an associated skeleton.'

Bongani: 'And your nine-year-old had just found it.'

Prof Berger: 'And Matthew had just found it.'

Charles Darwin first proposed the theory of human evolution in the late 19th century, the belief that all life descended from a common ancestor.

Although he never found fossils, he believed Africa would be the place to look for evidence of human evolution.

Bongani: 'Paleoanthropologists have only been studying fossils for the last 100 years. The first African hominid skull was found by Raymond Dart in 1924.'

It was also found in a lime quarry, this time in Taung, in the North West Province.
The Taung child, as its known, lived about two-and-a-half-million years ago and was only about three when he died. The species was called Australopithecus africanus and we are believed to be their direct decedents.

Twenty-three years later, palaeontologist Robert Broom discovered Mrs Ples, an adult Australopithecus africanus at the Sterkfontein caves. She could walk upright and had a relatively small brain, about the size of a chimp, with an intelligence to match.

Prof Berger is American by birth, but his need to know more about our origins brought him to South Africa. With determination he has walked these mountains searching for fossils for over 18 years.

Prof Berger: 'It's probably the hardest job in the world. We just don't find them. I mean, most people who are paleoanthropologists who dedicate their lives to this have never found one of these things in the field. I mean, we are searching for the rarest objects on earth.'

A few weeks after Matthew's initial find, Lee brought a group of Wits PhD students to look for more bones.

Prof Berger: 'Got here early in the morning. Two-and-a-half hours later we hadn't found a single definitive thing that we could say was a hominid. And as I was thinking of that the sun got just [high] enough - probably about 10:30 in the morning. And it was shining on the back wall, the wall that all of us had been searching dozens of times by then. And there sticking out of the wall was a proximal humerus, sticking literally 2cm out of the wall. I could not believe it. I climbed down in the pit and as I got about a metre away from that wall I saw next to it a scapular in articulation and I knew for sure at that moment we had the child skeleton'

Dr Job Kibii, a Kenyan paleoanthropologist, was present when Lee found the arm bone.

Dr Job Kibii (Paleoanthropologist): 'Let me tell you, the moment was nothing but magical. As a paleoanthropologist, that is what you are looking for, looking at fossils that will help you answer questions about human evolution.'

The latest technology was used in scanning the rocks to locate the skull of the child. Celeste Yates is a fossil preparator and she was the first to see the skull.

Celeste Yates (Fossil preparator): 'Exposing it bit by bit to see all sorts of things emerging and you're the first person to see it coming out after 1.9-million years... You're the first person to see it, to hold it, have a look at it, and virtually nobody has seen it before so you you're the only one... it was amazing, absolutely amazing.'

Over the next year, the site was carefully cleared and a paleontological treasure trove uncovered. The team not only found hominids, they also found a sabre tooth cat, a brown hyena, antelopes, and rodents.

Prof Berger: 'In a nutshell we have found the two most complete early ancestral skeletons ever discovered - a male and a female, a child and an adult - that existed in time when they died together and were probably related to each other.'

Two million years ago, the ground level would have been between 30 to 50 metres higher than it is today and the spot where the two hominids were found would have been a deep, dark cave.

Bongani: 'So would they have fallen into a type of a pit?'

Prof Berger: 'Well, they almost had to have because there is no scavenging. So no scavenger could get to them and survive and start eating them. Nothing that ended up down here lived except for maybe a couple of the small mice and stuff.'

The two skeletons are around 130cm long and would have weighed about 30kg each. They could walk upright on two legs like humans, but had particularly long arms and strong curved fingers, so could swing in trees like apes.

Bongani: 'In this story of evolution there is still much talk of a missing link, some transitional being that distinguishes us from the apes. It is in fact more accurate to think of evolution as a tree with missing branches. And this later fossil find falls into what Prof Lee Berger calls 'the muddle in the middle'.'

Prof Francis Thackeray is director of the Wits Institute for Human Evolution. He says sediba may fit between Austrolopithecus africanus and Homo erectus. There may have also shared other similarities with humans.

Prof Francis Thackeray (Institute for Human Evolution): 'But I would predict, yes, that sediba had the capacity for speech. Both sediba and Mrs Ples belong to the genus Australopithecus. They are perhaps 200 000 years apart. And since we've recognised that Broca's area - the language area - is present in Mrs Ples I would not be surprised if it were also present in the case of Australopithecus sediba, but that would need to be confirmed.'

Bongani: 'Tools?'

Prof Berger: 'Tools are a big deal. Everyone asked that question - did they use tools? And I think the reason that you asked that question is because that's something that we suppose is unique to 'us'. Other animals don't really do it. If we found tools in a site like this, in direct association with early hominids, it would be the first time anyone has ever found them in direct association.'

Bongani: 'You being a scientist, what's your sense? What does your instinct tell you?'

Prof Berger: 'On whether or not they had tools? Maybe.'

Like the Rosetta Stone, which unlocked the secrets of writing and language, this discovery may help us unlock the secrets of our evolution. Lee believes this may be richest early hominid site in the world, and that it may hold many other secrets about our beginnings.

Prof Berger: 'I happen to know that we are sitting within about a metre-and-a-half from another skeleton that, I know that for a fact, I've seen it. That is indescribable and that's not one of the ones we've found already. That kind of thing shouldn't happen in this field. And yet it's happened to me and it's happened to my team and it's a great feeling, but it's a powerful feeling too.'

Stefanus
12th September 2011, 19:04
Australopithecus Sediba

Date: 11 September 2011
Producer: Bernadette Cook
Presenter: Chantal Rutter
Show: Carte Blanche (http://beta.mnet.co.za/carteblanche/Article.aspx?Id=4427&ShowId=1)

http://www.wendag.com/Documente/flash/AustralopithecusSediba_1.flv http://www.wendag.com/Documente/flash/AustralopithecusSediba_2.flv
In 2008 a young boy and his dog stumbled upon one of the richest fossil finds ever in the Cradle of Humankind north west of Johannesburg.

[Carte Blanche April 2010] Matthew: "He said it was a hominid and I just couldn't believe it."

The boy's father, Dr Lee Berger, a paleoanthropologist from the Institute of Evolution at Wits was elated.

[Carte Blanche April 2010] Dr Lee Berger: "I was stunned I was even more stunned when I turned the block over and on the back of it was a canine and a mandible of a hominid and I knew that maybe we were dealing with an associated skeleton."

[Carte Blanche April 2010] Bongani Bingwa (Carte Blanche presenter): "And your nine-year-old had just found it?"

[Carte Blanche April 2010] Lee: "And Matthew had just found it."

The ensuing dig unearthed two of the most complete hominid fossils ever discovered and in April 2010 the scientific community learnt that Matthew had stumbled on a new hominid species - previously unknown to science that lived around two million years ago.

[Carte Blanche April 2010] Lee: "And this is arguably the most complete early human ancestor skull ever discovered."

This new hominid, Austropithicus Sediba, brought with it the promise of unlocking secrets to that impenetrable question - where do we come from?

Chantal Rutter (Carte Blanche presenter): "Since the discovery of this site in 2008, 80 scientists have collaborated from around the globe to try and make sense of this rare find."

Their intense studies have revealed Sediba is a species in transition, with unique features that suggest Sediba could be the missing link. This week their research culminated in five papers being published in the prestigious journal "Science". It's unheard of says project leader - Prof Lee Berger.

Lee: "These five papers studied these two skeletons in-depth and new material from these skeletons. We have a young male - he's the holotype or type specimen - he's about 13 years of age and an adult female."

This seminal fossil find has provided a rare insight into a kind of early ancestor scientists only imagined possible - it's part ape and part man. In our family tree it fits after Lucy, mankind's original ancestor from east Africa and Mrs Ples on the one hand and before Homo Erectus on the other - possibly dislodging Homo Habilis as our immediate human ancestor.

Lee: "Last year we said that these fossils lived between 1.78 and 1.95 million years ago... that's all changed. Now with new advances in uranium lead dating and paleomagnetic dating which looks at reversals in the Earth's magnetic pole - we've achieved the most accurate dates ever achieved on this continent or maybe on any continent."

Dated as 1.977 million years old - the Sediba fossil have taken Lee and his team on a fascinating journey of discovery.

Lee: "We've applied state-of-the-art technology to every aspect of the anatomy of these skeletons, because of their importance, because of their completeness because of their other uniqueness."

Using groundbreaking 3D imaging technologies - they have been able to analyse Karabo, the younger of the two Sediba fossils brains.

Lee: "We used it to look at the brain and produce the most accurate scan that has ever been produced of an early human ancestor brain."

Dr Kristian Karlson, a Human Evolution researcher at Wits - conducted the studies into the brain.

Dr Kristian Karlson: "We took this to a local hospital and we CT scanned it and this allowed us to see what was inside and so we were able to using computers, remove the inside of the skull which is containing the brain of course and we made a model that's like this."

Wanting even higher resolution, Kris then took the mould to France to create the best mould of a hominid brain ever made - this is the 3D printout.

Dr Karlson: "That was for us a breakthrough because we now had an opportunity comment on this brain, to a much greater extent. Here we could talk about size whereas now we could combine size with regional differences."

Although Karabo's brain was three times smaller than a human brain it was advancing along human lines.

Dr Karlson: "We see some re-organisation, especially if you look at the bottom surface here where you see more protrusions up behind the eyes here and shrinking of areas further back. So we are seeing areas of the frontal lobes that are beginning to change relative to the ways humans differ from chimpanzees."

These changes would affect mental capabilities like future planning, multi-tasking and intelligence.

Dr Karlson: "Reorganisation happening suggests see bigger areas related to this multi-tasking and reasoning not nearly human like but becoming more human like relative to earlier Austropithices like Mrs Ples."

The fossils differ quite vastly from our earliest known ancestor too.

Lee: "This fossil differs from Lucy in a large number of ways in many ways it's much more advanced, the brain shape is more advanced than Lucy was, its teeth are more advanced, they are smaller, they look more like our teeth in some ways and different in others."

The findings from these near complete skeletons puts a whole new spin on human ancestry according to Dr Tracy Kivell, who spoke to us via Skype from Germany.

Dr Tracy Kivell: "There are combinations of morphologies that we didn't think were possible to find in a human ancestor... in the hand for example there were features that were put together that I didn't think were possible and I think that if we found these bones separately we would not have thought they were from the same species let alone from the same individual."

Chantal: "What does this tell us about evolution?"

Dr Kivell: "It says that that evolution doesn't necessarily happen predictable ways and so yeah it just says that evolution and understanding our own evolution is probably more complicated than we even thought it was before."

Lee: "In almost every area of the anatomy whether it's the brain or the hand or the pelvis or the ankle - what we are seeing is anatomy that is different than the way we thought evolution had worked at that period."

Kenyan born, Dr Job Kibii, believes that this species which falls into the transition period has literally put the pieces of the puzzle together.

Dr Job Kibii: "We're talking about a creature that had good manipulative abilities to make stone tools but the fingers were curved indicating that it maintained climbing abilities and it's a hominid like no other."

The hand is human-like at the end of an ape-like arm with a surprisingly long thumb and fingers capable of making stone tools.

Dr Kibii: "Sediba has a long thumb which is relative to the fingers even longer than in human which is important in precision grips."

The foot and ankle joint is also a combination of human and ape features - according to Dr Bernard Zipfel - senior curator of Collections at Wits.

Dr Bernard Zipfel: "We have no doubt that this was a biped, probably a habitual biped and at the same time we are seeing features that are saying it might have been just as at home in trees."

Lee: "The foot itself is remarkable - there you have in the ankle bones put together that should not work by our current models - the calcanious or pedal bone - it actually looks like a chimpanzees but its attached to the next bone that leads to the foot, the talis bone and it looks almost just like a human."

Couple this with Sediba's small brain and a pelvis is ready to give birth to babies with bigger brains - Sediba's anatomical combinations raises questions about our lineage.

Dr Bernard: "It's beginning to tamper a little bit with our understanding of the family tree and where these creatures fit in because what we knew before might not be what we thought it was and that's what makes a find like this so exciting."

Chantal: "There has been no controversy over whether this is a new species - instead the debate has been whether this should be placed in the genus homo."

Lee: "We didn't put this in the genus homo because we felt that was the conservative thing to do - we felt it had not made that pardon the pun step towards being exactly like we are - that is a fundamental habitual terrestrial biped that has the short arms and the big brain and all the things that make us as a total package."

Chantal: "The Cradle of Humankind World Heritage site is one of the richest fossil sites ever discovered. As excavations continue more clues will be unearthed as to the origin of humankind."

Lee: "It has placed the cradle of humankind squarely on the map of a critical if not the most critical spot in Africa for understanding our origins."

Dr Kivell: "Africa is where evolutionary origins lie and I think that everyone has a distinct fundamental interest in where we come from and Sediba sheds some new light on that question.

With three more hominid fossils still to be unearthed - South Africa is set to take centre stage in unlocking our evolutionary secrets.

Lee: "Southern Africa is going to reveal a record that is so extraordinary and so complete and now that we can date it - so contextualised that we are going to learn things about our origins that we never dreamed of just a few years ago."