Meave Leakey Interview (page: 3 / 7) Pioneering Paleoanthropologist	Print Interview

What makes the Turkana area so rich with these ancient fossils? Why there?

Meave Leakey: If you look at a map of Kenya, and you impose on it all the archaeological pre-history sites, they're all down the Rift Valley. The Rift Valley goes right through the middle of Kenya. Lake Turkana is the biggest lake in the Rift Valley, in Kenya, and it's a huge lake basin. The rift is important because it was formed as a slight depression that got deeper, and water drained into the depression, taking with it sediment, and the sediment buried any evidence of life or archaeology or whatever. So that was then buried and preserved. Because the rift is still forming, and erosion is still taking place, things that were buried four million years ago or three million years ago are now being exposed in some places. The whole process is one of continuity. There are still things being buried and still things being exposed. So that's why all the sites are down the Rift Valley, and the Turkana Basin has been a sedimentary basin since -- the formation of the Turkana Basin has been well over four million years. So there's a relatively continuous sequence that goes from four million years up until present time, and it covers exceptionally well the time of the emergence of Homo and Homo erectus and that time interval.
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This is how long ago?

Meave Leakey: Two million years and less. That's on the east side of the lake. In other areas of the basin it goes back to as much as four million. So there's a really very good record of that whole time interval from four million years until Homo sapiens appears. So it's just a fantastic record.

We've read that this area was particularly rich in hominid fossils, especially in the first years.

Meave Leakey: Yes...

Those early years were really exceptional. We didn't, I don't think, at the time, appreciate really how lucky we were. Because we were going into this huge site that nobody else had worked, so nobody had been in there looking for fossils. So everywhere you went, there were the most incredible fossils and many of them were specimens of our ancestors. So you know, we were finding sometimes more than one a week, and if we didn't find one a week, we felt we were doing pretty badly. Now it's quite different. Now you really have to look, but the evidence is still there. There's still an enormous amount of work to be done there. It's just a really incredible site and I think it would be difficult to find another site to match it in Africa at the moment. And added to that, because we've been working there now on the east side since 1968, the east and west side, and the Omo Valley was actually worked before that. So there's a record that people have been working there for decades now, and so (we have) that basic data and basic understanding of the lake's history. We now know where the sites are, how old the sites are, and if you want to answer a particular question, which the best sites are. Now we're going over sites that we worked 20 years ago or more and finding more things have eroded out. But we go there knowing the background of the site. We know the background of the evolution of the animals, of the humans, of the environments, and so we have a good context to put everything in now. So it's really very special.
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You made an extraordinary discovery in 1994. Could you tell us about that?

Meave Leakey: At the time, the earliest fossil of human ancestor that was known was Australopithecus afarensis, better known as Lucy, that Don Johanson had found in Ethiopia. And Mary Leakey's footprints, which were found in Tanzania. That was the earliest evidence of bipedality, people walking on two legs, and of human ancestors. The theory was that this was the common ancestor of everything that came afterwards. But...

We knew from molecular evidence that apes and humans split around about five or six million or maybe even earlier. And it seemed odd that there was no diversity, nothing really much going on in that time. We felt that it was more likely to be due to lack of evidence than the reality of the situation. So what I wanted to find out was "What went on before afarensis? What happened before Lucy? Who is Lucy's ancestor?" We thought that 4.1 million was the perfect age, because it was pre-Lucy. What we found there was a number of -- not complete skulls -- but parts of jaws, and also a leg bone. The leg bone showed clearly that at 4.1 our ancestors were walking bipedally, so it took back the evidence of bipedality. It also showed that the things we were finding were more primitive, more ape-like in many ways, to afarensis. So it really took back the record earlier, and made a very good ancestor for Australopithecus afarensis, in fact. So it didn't show there was any diversity in the earlier time, but it did show that you could take the record back. Since then, of course, there have been more staggering specimens discovered, going back towards six million.
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A later discovery of yours created quite a stir, didn't it?

Meave Leakey: That was in 2001.

Once we had worked the site at 4.1 million, which is called Kanapoi, we decided that we could work at a site that was the same age as Lucy and see if we could find afarensis, or whether we'd find something else. Because again, I was still thinking that there should have been diversity at that time, and it shouldn't just be the common ancestor there, but it should go back further. So that's why we were working at that age, 'cause it was the same age as the sites from which Lucy came. What we found there was a skull, and other specimens as well. But we only named the skull because we couldn't relate the other specimens directly to the skull. But the skull had a very flat face and a very long face. Lucy's face is much more protruding and much more ape-like in many ways, actually. The face shape showed that the species was not afarensis, it was something different. So it showed that there were at least two hominid species living at the same time as Lucy. So therefore, Lucy wasn't necessarily the common ancestor. It could have been the species that we found, that we called Kenyanthropus platyops, or it can be something else that we haven't yet found. I believe sincerely that in the end, there will be several different things found at that time as there are later.
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So this was not just a new species, but a new genus?

Meave Leakey: We note a new genus and species because it just didn't fit into any of the genera that were known. It may in the end prove that you can fit it into another genus, but for the moment it made more sense to call it a new genus. You didn't know, if you're going to put it in another genus, whether it was better to put it in any of the known ones. It just didn't fit.

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