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Fossil Find New Branch in Human Family Tree?
 CBSNews
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April 14, 2010
| | The fossilized skull and bones found by a boy with his scientist father are the discovery of a lifetime and may prove to be a new link in the human evolutionary chain. Bob Simon reports. (CBSNews) | |
Where do we come from? That's often the first question a child asks and it has bedevilled scientists for centuries. Well, today we're a little bit closer to answering it.
This past week it was announced - with great fanfare - that the remains of a nine-year-old boy were found in South Africa. He is almost two million years old.
He's being called "Sediba," which means "source," and he stands somewhere on the road between ape and human. He lived in a period when our ancestors climbed down from the trees and started living on the ground. He belongs to a previously unidentified species and anthropologists will be studying him for decades.
Before the announcement, "60 Minutes" and correspondent Bob Simon were given rare access to the discovery, which could be among the most important of our time.
His unveiling was a major happening this past Thursday, when he appeared at a press conference in Johannesburg.
Professor Lee Berger, an American paleoanthropologist at the University of the Witwatersrand, named him Australopithecus sediba. And the most astonishing thing about him is his skull: 1.9 million years old and so well preserved that you can count his teeth - so very much like ours.
Where did Sediba live? In hills just 50 minutes from Johannesburg, in what is called the "Cradle of Human Kind." After all, we humans came from Africa. And scientists there have spent the better part of a century looking for fragments of our earliest ancestors.
"There's probably nowhere else on planet Earth that has a denser, better record of human origins than this land right here," Berger explained.
Yet Berger had been searching for fossils in caves here for years and hadn't found much of anything. So he started a mapping project using a very modern tool: Google Earth. He discovered some 500 caves in the region, which no scientists had ever explored.
"And then I started walking. And I walked a lot. Hundreds of kilometres," he explained.
Berger was walking through the Malapa Nature Reserve with his trusted dog Tau, his nine-year-old son Matthew and his colleague Job Kibii.
They came across a cave and that was the beginning of an astonishing series of events.
"I...literally said, you know, 'Here's the site. There are bones here. Let's look around.' Matthew got up, ran over in that direction. A minute and a half later, he called me," Berger remembered.
Matthew found something which he knew would excite his father. "Here's a rock that looks about the same size and when I turned it over there was a fossil," Matthew Berger explained.
"I looked at that fossil in that rock and knew exactly what he had found," his father recalled.
He had found a clavicle, a collar bone.
"That clavicle alone would've been a great find. It would have been enough for me certainly. You know most people who do what I do, do what Job do, go through their entire careers and never find even a single piece," Berger said. "I had found a few dozen fragments, I mean fragments, before this."
It gets even better: on the other side of the rock there was a jawbone and a tooth - a canine.
"That was amazing," Kibii said. "We would turn to the clavicle. We high-fived. We turned to the canine. Because we knew that we have hit a jackpot."
Hitting the jackpot, without even digging. Why was it so easy? A hundred years ago miners blasted these caves, scattering rocks and unearthing fossils, fossils including a skull.
Berger and Simon stood in a pit where Berger pointed out exactly where he found the skull. "It was lying on its side, sticking out of the wall. Its foot is still in the rock just up at the top, there," he explained, pointing to it.
Berger sent the rocks to his lab at the University of the Witwatersrand, where workers began painstakingly extracting the fossils. The dating of the rocks showed they were around 1.9 million years old. Analysis of the bones revealed that what the scientists had in their hands was not one skeleton but two: a nine-year-old boy and a 30-year-old woman.
"I think it really is a most remarkable set of finds, and particularly the quality. I don't think we've found anything like this before," Richard Leakey told Simon.
When Leakey, the world's most renowned paleoanthropologist, examined the bones, he said they were almost too much to digest. "It was a wow experience," Leakey recalled. "I mean, there's a lot of stuff there. And it's spectacular. It is so full of information, so much data, that I had to say to him after an hour, I said, 'Lee, I've had enough.'"
"Lee is still finding bones in that cave. Has he struck a gold mine?" Simon asked.
"Yes, he's got a treasure trove. No question, a treasure trove," Leakey said.
Back at the site, Berger and a team of geologists were trying to figure out exactly what had happened 1.9 million years ago. What had these creatures been doing?
Berger's best guess: they were searching for water and accidentally fell into the cave.
"This is a single event. This is not something that happened over years or decades or hundreds of years, which is often the case with other fossil sites," Berger said. "This is a moment in time. It happened in seconds, minutes, days or weeks."
Asked how he knows that, Berger explained, "Because it's one single unit of geology. Everything is together, and everything is articulated so that, you know, almost for the first time in history we can tell you that these two individuals looked each other in the eyes when they were alive 1.9 million years ago."
A glance frozen in a fossil? Berger thinks so. But he's been accused in the past of letting his imagination roam a little too freely. Nonetheless, he says it's probable that these two creatures were related.
"They are just primates, like we're just primates. Primates live in troops. And these troops are very often related to each other," Berger said.
Asked if they could speak to each other, Berger said, "I don't know whether they could speak to each other. But maybe we'll know one day."
"Did they have tools they could use together?" Simon asked.
"Given what we're seeing in their shape and form, there's no real reason to suggest that they might not be capable of manufacturing complex stone tools," Berger said.
But Berger does not think they had the skill to make fire.
But whatever they could or could not do, they are some of the rarest objects on Earth. Their value is priceless. For Berger, the thrill is putting the bones, the jigsaw puzzle, back together.
Standing in the lab where the bones were stored, Berger showed Simon how he could put the woman's femur back into its socket. "It's like reconstructing her life," Berger explained.
And young Sediba? His relatively long legs tell us that he could walk and run on two feet. His long arms and powerful hands suggest that he also felt at home in trees.
And what about his skull?
"Isn't it extraordinary? There's a face from 1.9 million years ago," Berger remarked, lifting the skull out of a protective case.
"How old is Moses?" Simon joked.
"A few thousand years. Nothing compared to this," Berger replied. "A few seconds in the relation to the time this has been around. It's almost a work of art, isn't it?"
But how do you compare this work of art to something more contemporary?
Simon pulled a cast of a skull from a modern human from the shelf and set it beside the Sediba’s skull. "You told me before that this chap is 40 years old, and this chap is almost two million years old. How do you compare them?" Simon asked.
"You can see that little Sediba has a nose here," Berger said, pointing to the fossil. "The face is very similar in shape. And even surprisingly the teeth are almost the same size," Berger said.
Sediba's brain is smaller than ours but larger than an ape's. Berger calls him a hybrid - a strange mixture, an entirely new species.
Asked what is special about this species, Berger said, "This one doesn't just fall in that big picture between the apes and us, if you will. This is falling at a critical moment where we almost had no evidence. And I really do mean that; literally just a few fragments. It's a period between where we turned from effectively an ape man to something that is very, very close to us."
Simon spoke to Donald Johanson, the man who discovered Lucy, the most famous fossil ever found. "Do you think it will take awhile before Berger's discovery and interpretation become universally accepted?" Simon asked.
"No doubt. No doubt," he replied.
When Johanson discovered "Lucy," it took years before his views were accepted.
"Why do you think this whole area is so contentious?" Simon asked.
"We have an emotional commitment. People are studying the origins of all humankind. And everybody who finds fossils, finds a human fossil like this, becomes emotionally involved with them. We want our fossil to be on the tree. We want our fossil to be an ancestor to all humanity. And I think that's something that colors our thinking," he replied.
Today, to examine and re-examine his own thinking, Berger is using the most up-to- the-minute science to study these most ancient of creatures. He recently took Sediba on a trip to the ESRF in Grenoble, France, to one of the world's most sophisticated x-ray systems, called a synchrotron.
Just a few years ago, you would have had to destroy the rock surrounding Sediba to get a good look at him. That's not necessary now since the scanner sees right through the rock. It can fill a screen with something one one-hundreth the size of a human hair.
"It's gonna peer into him and it's gonna tell us what treasures sit inside of him that we can't even imagine," Berger said. "I mean, we've really never been able to look at this level inside of something in our ancestral lineage that's as complete as this," Berger explained.
Scans of Sediba's teeth will tell scientists not only what he ate but where he ate it, on the ground or in a tree. And, to a day, how old he was when he died. Sixty scientists are already working on these questions - it's a sort of "CSI" for fossils.
"This is like a time machine. We're gonna go back and look at their world," Berger said. "It is an adventure that we're right at the front pages of. And it's kind of like reading the greatest novel ever written, the human story. It's an incredible adventure that we're going to see the end to."
And it all began with a nine-year-old boy discovering another nine-year-old boy. You couldn't make that up. |
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