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| BRANCHING OUT
DECEMBER 13, 1996TRANSCRIPT |
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In the last few years it came to light that Neanderthals and Homo sapiens (modern man) walked the earth at the same time. Now a study in the journal Science reports that Homo erectus, an ancestor of Homo sapiens, lived as recently as 30,000 years ago, meaning that they shared the earth with humans and Neanderthals for thousands of years. Dr. Richard Potts, Director of the Human Origins Project at the Smithsonian Institute discusses what this finding does to our view of mankind's evolution.
A RealAudio version of this NewsHour segment is available.
Online NewsHour links
December 9, 1995:
The Smithsonian's Richard Potts discusses the career of the late, ground-breaking archaeologist Mary Leakey.
November 26, 1995:
David Gergen engages noted Harvard biologist Stephen Jay Gould in a discussion of his new book Full House.
Browse the Online NewsHour's science coverage.
CHARLAYNE HUNTER-GAULT: Modern humans may have had more company than we thought--a third human species alive and well and living in Asia for tens of thousands of years. That's the startling and controversial new research finding reported in a study out today in the journal Science.
A team of scientists contends that the species, homo erectus, believed to be an ancestor of modern humans, existed as recently as 27,000 years ago, long after scientists believed it extinct. That would mean homo erectus lived alongside modern humans, homo sapiens, for thousands of years. The third species, the Neanderthal, was also alive at the same time. For some insight into these findings and what they could mean for the tree of life, we're joined by Richard Potts, director of the Human Origins project at the Smithsonian Institution.
And welcome back, Dr. Potts. We just spoke to you earlier this week about Mary Leakey. Now on this, first, briefly tell us what the conventional wisdom is that we had our origins and how this changes it.
RICHARD POTTS, Smithsonian Institution: Sure. We used to think that our family tree, the human family tree, was pretty simple. You could draw it as a trunk, a tree with a trunk, simple trunk through time which led from, as we see in the fossils, replicas that we have here.
CHARLAYNE HUNTER-GAULT: These in front of you here.
RICHARD POTTS: Yeah. We have exact replicas of some of the fossils that are being discussed in today's news, and we can see in the simple view that there is a transition from homo erectus, that lived starting back in Africa about 1.8 million years ago, but then lived for a very long time, was a very successful species, but then were was a transition to more modern-looking forms and, ultimately, to modern homo sapiens, people who look like us, and of course, we are one species all today, just a single species living today.
CHARLAYNE HUNTER-GAULT: And the difference between these and these--these don't have faces, but in--when they existed, what was the difference between these two and these two?
RICHARD POTTS: Right. Well, as you can see from these, that you have a--basically a very heavy brow ridge. The face would have been down like here. And a very heavy brow ridge, and you could notice that the brain case arcs at a very low angle. It had a cranial capacity that was significantly less than that of modern human beings. We have here a Neanderthal, for example, as an example, and here we see again a much larger brain case than in homo erectus, and we have still, though, a heavy brow ridge. The brain case still arcs at this low angle, then as an example of modern human being, we have a repackaged brain case. It looks more of a globe or a sphere with relatively little brow ridge. And so the news today of this particular form, homo erectus, living at the same time as this particular form, well, there are no anthropologists, or at least very few anthropologists who would claim that these are the same species. There has been a long series of debate about the Neanderthals and modern humans that whether they might have inter-bred, whether they represented one species or separate species, but the homo erectus, living at perhaps anywhere from twenty-seven thousand years ago to fifty-three thousand years ago, that's what the new report says, that's astonishing. It means that there are at least two, possibly three, different species of humans walking around at the same time.
CHARLAYNE HUNTER-GAULT: And what does that mean?
RICHARD POTTS: Well, that means that our family tree is no longer a trunk. It means that it's a bush. We used to think that it was always a trunk, but starting about ten years ago, we began to realize that the early part of human evolution was, in fact, a bush with many side branches, that there were many different what we might think of as experiments in being human, as I often call it. We know that that bushiness of our family tree lasted up until very recent times.
CHARLAYNE HUNTER-GAULT: But once we know that, what do we know?
RICHARD POTTS: Well, it's a good question, because it brings up perhaps "the" most important. Today's report deals with what I think of as the "what" and "when" questions of our origins. What species is it and when did it exist? There are other questions that the new report suggests that we would ask, and that's the how and why. Why were there different species? Why did the human experiment, the evolutionary experiment, lead to several different species, and why was ours the one that persisted, while others died out?
CHARLAYNE HUNTER-GAULT: Was it in the past, that maybe those earlier forms died out through wars or fighting or something like that?
RICHARD POTTS: Well, it could be that on the island of Java, which is where the new dates have been obtained, and these particular replicas of the fossils come from theisland of Java, and that may have been a refuge where the life ways of homo erectus could have survived for longer than it did in other parts of the world. If it was a refuge, well, then it brings up the point that modern homo sapiens, which has persisted, of course, to the present may have been adapted to the much wider ranges of environmental changes. We have evidence for dramatic environmental change over the last million years. It's during that time that modern homo sapiens evolved, and, clearly, we are certainly and adaptable hominid or early human.
CHARLAYNE HUNTER-GAULT: Well, did the brain capacity have anything to do with the survival?
RICHARD POTTS: It could have. It could have. Brain capacity. We carry sort of our own laptop computers on top of our skulls, tremendous computing capacity, able to take in a lot of environmental information, respond to it, and it seems, based on what we know from the behavior of homo erectus, that they lived what we might think of as a rather monotonous lifestyle, making stone hand axes for hundreds of years in pretty much the same way.
CHARLAYNE HUNTER-GAULT: Is there anything in these new findings to suggest that these two got together, I mean, co-habited, or played cards together, or whatever--whatever they did?
RICHARD POTTS: They certainly showed that homo erectus and modern humans, if, in fact, the dating is correct, they show that the two species were around at the same time on earth. But there is no evidence that I'm familiar with at least that modern homo sapiens and these particular skulls of homo erectus from the Solo River of Java were there at the same time.
CHARLAYNE HUNTER-GAULT: But there's controversy in at least two associated with these findings.
RICHARD POTTS: Yeah.
CHARLAYNE HUNTER-GAULT: Very briefly, tell me about those.
RICHARD POTTS: Well, there's the out-of-Africa idea, which is to suggest that your transition from homo erectus to homo sapiens occurred in a small series of populations, or maybe in a single population based in Africa. Those modern homo sapiens then spread out across the world and replaced archaic-looking hominids such as homo erectus in other places. The continuity model is the other model. And that suggests that this transition from one species to another took place over a broad area--Asia, Africa, and Europe.
CHARLAYNE HUNTER-GAULT: Not just Africa.
RICHARD POTTS: Exactly.
CHARLAYNE HUNTER-GAULT: And the second controversy has to do with the findings, themselves, and how they were done, right?
RICHARD POTTS: Indeed, indeed. There's always, in science, we live in a community of doubters, as I call it. We're all skeptics. And this is wonderful news. The lab at Berkeley that did this work is very, very good, but there are always going to be doubts and questions about how and where they got the dating. And this will have to be--involve many other labs, and perhaps trips to Java to find more fossils.
CHARLAYNE HUNTER-GAULT: Because they didn't find--it wasn't the fossils that they found, new fossils that they discovered. It was just a new technique.
RICHARD POTTS: Exactly. They didn't date the human fossils, themselves. They dated an antelope's tooth that was associated with the fossils, and in a river setting, it could be that fossils of different ages were mixed together.
CHARLAYNE HUNTER-GAULT: Okay. So lots of questions. Well, that's what we're here for, so maybe one day we'll do it again. Thank you for coming.
RICHARD POTTS: Thanks very much.
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