Ardi
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Ardi Source: Science
An international team of scientists has been investigating Ardipithicus Ramidus, or Ardi for short, a 4.4 million-year-old hominoid skeleton. Ardi is opening another window on ancient human history according to the team’s research published today in the journal Science. Anchor Marco Werman gets details from project co-director and paleontologist Tim White and evolutionary biologist Owen Lovejoy.
For today’s Geo Quiz we’re looking for a geological feature in East Africa. It’s in an area considered one of the cradles of humanity.
Fossils of ancient humans have been preserved here for millions of years. Paleontologist Tim White has been uncovering them:
“Ethiopia is a unigue geological setting where you have 3 rift valleys coming together, intersecting. Two of these are full of sea water now that’s the Red Sea and the Gulf of Aden … The continental East African rift running down thru Tanzania and Kenya is coming up into Ethiopia and entering a triangular depression right at the intersection of these three rifts.”
That triangular depression. That’s the feature we want you to name. There’s big news from there today. Scientists have filled in some missing pieces in the story of human evolution.
We’ll have that news — and the answer…
There’s a new kid on the block we want to tell you about. Actually, she’s very old. 4.4 million years, in fact. Her name is Ardi. That’s short for Ardipithecus Ramidus.
Ardi is believed to be an ancestor of… well… us. Ardi is an ancient hominid, and she’s much older than Lucy — the much-studied human ancestor who lived around 3.2 million years ago. A team of scientists discovered Ardi’s skeleton back in the 1990′s. Finally, after painstaking work, they’re announcing detailed findings today in the journal Science.
Tim White is co-director of the team. He’s a paleoanthropologist at U.C. Berkeley and Owen Loevejoy is a paleobiologist at Ken State. Professor White, can you handle the introductions from here please introduce us to Ardi?
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The answer to today’s Geo Quiz is Afar Rift, Ethiopia, nicknamed the cradle of humanity.
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MARCO WERMAN: I’m Marco Werman. This is The World. There’s a new kid on the block we want to tell you about. Actually, she’s a very old kid. 4.4 million years, in fact. Her name is Ardi. That’s short for Ardipithecus Ramidus. Ardi is believed to be an ancestor of… well… us. Ardi is an ancient hominid, and she’s much older than Lucy — the much-studied human ancestor who lived around 3.2 million years ago. A team of scientists discovered Ardi’s skeleton back in the 1990′s. Finally, after painstaking work, they’ve announced detailed findings today in the journal Science. Tim White is co-director of the team. He’s a paleoanthropologist at UC Berkeley. And Owen Lovejoy is a paleobiologist at Kent State University, and congratulations to you both on this discovery and the research. Professor White., introduce us to Ardi.
TIM WHITE: Thanks for having us. The first thing to say is this is the research of 47 different scientists from 10 different countries, and it’s very long-term and protracted research.
WERMAN: Absolutely.
WHITE: And it’s given us an amazing picture of world that has vanished. It’s a world that was 4.4 million years ago, and we’re announcing here not only the remains of this female skeleton we’ve nicknamed Ardi, but many other individuals of the same species represented, not as well, not by whole skeletons…And, even this is not a whole skeleton but it gives us all the really vital parts to understand the phase of human evolution that came before Lucy.
WERMAN: What do those extra 1.2 million years give us in terms of information? What do we know now we didn’t a couple of years ago?
WHITE: Let me take it from the top of the head, then I’ll pass it to Owen. The skull is very small, the smallest adult hominid brain size that’s ever been found. This is not a “frugivore,” specialist, like a chimpanzee, it’s a generalized omnivore, at least from what we can tell about its teeth and head.
WERMAN: What is a “frugivore?”
WHITE: It means it’s a fruit eater, and that’s what chimpanzees really go after, in the high canopy. And they’ve evolved a whole series of adaptations in their teeth and in their social structure, even, that’s patterned around this food resource.
WERMAN: It sounds like she could be in the trees and maybe swing you around like a chimp, but also walking upright like Lucy did, almost like a human.
OWEN LOVEJOY: You’re almost right. She didn’t do a lot of swinging. The swinging, or “breakiation,” as it’s called, is something that chimpanzees and gorillas do. But in fact, Ardi had a really flexible palm. And a very special structure to her wrist joint, so that she could support herself above branches on her palms and had very flexible forelimbs with which to get around the lower canopy.
WERMAN: How much have you been able to conclude about Ardi’s life? Do you have any idea what she thought about?
LOVEJOY: She’s undoubtedly nesting in trees as do chimpanzees and female gorillas. She probably has a sub adult offspring she’s caring for. She probably does a bit of foraging in the lower canopy. But then, becomes terrestrial and does foraging there. She probably has to get from one point to another. When she does this, she’s bipedal on the ground.
WERMAN: So Ardi and the other specimens found nearby, all discovered in Ethiopia. Tell us precisely where the finds were made.
WHITE: It’s called the “Afar Depression,” or the “Afar Rift” of Ethiopia. It’s, today, a very harsh desert. But for millions of years, lakes and rivers on the bottom of this depression have been depositing sediment. And as plants and animals died, their remains were covered with this sediment. And sort of preserved. Today, these ancient sediments are being exposed on the surface of the Afar and with each rainstorm, you have new fossil remains coming out of these various layers.
WERMAN: Ethiopia’s Afar Rift. The answer to the Geoquiz today, if anybody is still paying attention to the Geoquiz [LAUGHS], because I’m still fascinated by this story. It sounds pretty magical out there in the Rift valley. Do you expect more sediment to kind of, peel away further layers of equally exciting discoveries?
WHITE: Well, our team has now surveyed most of the study area, working under permit from the Ethiopian government. So each year we go back to localities that we know to be fossiliferous. And that’s how this new Ardi skeleton was found. The first fragments were from the palm of the hand found by a former Berkeley graduate student, Johannes Haile-Selassie. Johannes recognized it was a hominid, but we had no idea there was still a partial skeleton embedded in that hill. And so it took us three years just to excavate the little hill. And then a lot of other years to work on this skeleton to put together a very comprehensive picture of Ardi’s work.
WERMAN: The discovery of Lucy in 1974 was said to be a once in a generation kind of discovery, and now this. Tell us about a personal moment when the magnitude of this discovery really hit home.
LOVEJOY: Probably….had a “eureka moment” for [PH] Gen Sua, who did the virtual reconstruction of the skull. CT-scanning all the little pieces, and each one’s about the size of a nickel, to a quarter. Every one of those CT-scans had to be virtually assembled in space. And I’ll bet you he had a thousand eureka moments when he got a fit between Piece A and Piece B. I worked on the pelvis, and it took us six years to reconstruct that. So, for the laboratory people, it’s a long series of eureka moments.
WERMAN: And of course the Ethiopian government gets some credit for this. Because, after all they give you the permits for these digs. Will Ardi be kept for exhibit and for the study in Ethiopia?
LOVEJOY: Yes, all of the fossils that we’ve collected on the [PH] Middle A.W.A.R. Project since 1981 have stayed in Ethiopia. The only exceptions’ are taking the fossils for brief periods outside where the technology is not available in Ethiopia. Like with the micro-CT-scanning. But they’re returned. They’re permanent national treasures in the National Museum of Ethiopia.
WERMAN: And will Ardi be near Lucy’s room at the museum?
WHITE: [LAUGHS]
LOVEJOY: They’re right together. And they’ll be in the same locked room, in the same vault. And it’s because of Lucy’s presence, because of all over anatomy, that Ardipithecus becomes such an important new fossil! Now, we can compare them and understand what happened as we move through time. In Ethiopia, in this study area, six million years of time.
WERMAN: Professors Tim White and Owen Lovejoy were among the 47 scientists from 10 countries that worked together to investigate Ardi, our newest ancestor. Thank you both very much, and congratulations again.
WHITE: Thank you!
LOVEJOY: Thanks a lot.
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