Posted to the web April 19, 2002
Charles Cobb Jr.
In a television documentary scheduled for airing on the Discovery Channel this Sunday, humankind is said to share a common genetic link that can be traced to one woman who lived in Africa more than 150,000 years ago. Using a unique part of human DNA called mitochondrial DNA” which is passed from mother to daughter, “The Real Eve”, narrated by actor Danny Glover, tracks the movement of humanity from this common ancestor across geography and millennia. AllAfrica’s Charles Cobb Jr. spoke with the film’s producer, Paul Ashton. Excerpts:
Q: We should start with the science and the point the film is trying to make. Can you explain this in layman’s terms? DNA? The “real” Eve?
The point of the film is to tell a story about the movement of people, where we came from and how we got to where we are now. And the new genetics are able to tell us how we got to where we’ve got now. And where we moved to and through. So Mitochondrial DNA, which is the maternal line carried by everyone – its the DNA of the mitochondria – becomes key. Mitochondria are like little batteries that energize everybodys’ cells. They have their own DNA which you can trace. Men cannot pass it on, only women. The mitochondrial drops off the sperm as it enters the egg. Every so often there is a very small harmless mutation which doesn’t effect anything other than that scientists can read it; they can see the mutation. Basically they can see which mutation came first. So every mutation is layered on the previous one. It’s always passed on exactly as it is. And where there is a split in the mutation you can tell that is where populations must have split. If somebody carries the same mutation up to a certain point along with another population and then suddenly they are carrying a new mutation which that other population no longer carries you know that group must have left before that second mutation.
Q: And these mutations would be what? Color? Hair? Body features?
No. Nothing to do with us. Mutation is a word that always conjures up that sort of thing but it’s actually a marker. It has no effect whatsoever because it’s within the midochondria. And it’s just something that we can see but it has no effect. It has no relation to our color or height or our eyes or anything like that at all.
Q: Okay. This sounds like interesting science, but a film? What in this science leads you to a film?
Well, the film is about our human journey. Everybody on the planet carries the midochondrial DNA of one woman who lived 150 thousand years ago in Africa.
Q: Where in Africa?
We think in East Africa. Archaeologically we know that. You can’t tell that from genetics. Archaeologically we know pretty well that we came from the southern end of the great Rift Valley. Also, the genetic markers around that area are numerous too, so that’s the most likely place that we arise from as well.
I do have to tell you that although I am telling this story, the reason I am able to tell this story is because I have done a lot of work on it over there last two years, but I am not a scientist. There is no way that I can explain all of the technical, academic details. So basically we know that we all carry the genetic marker of one woman who lived over 150,000 years ago in Africa, but then we talk about how did human beings first leave Africa and where did they go to then. Well, because of the genetic tracing we know that everybody outside Africa carries a mitochondrial marker of one woman who must have been in a group of people who left Africa about 80,000 years ago. And we know that group was a group of anything from about 250 to 700 people. We think it’s about 250. Less than 250 wouldn’t have been able to sustain a population and much more than 500 or 600 people would have taken too long for it to drift down to one line because they have to stay together. We also know that it was one group that left once. It wasn’t a stream of people. It wasn’t lots of groups leaving at different times. It had to be one group once because it all comes down to one line. For example, if you take a small remote Italian village you will find that a lot of the people in the village carry the same name. That’s over time, because some people just have daughters. You drift down to one name. In same way you drift down from one line. So there might have been lots of lines coming out of Africa in this one group but because they stayed together sufficiently long enough they all drifted down to one line.
Q: Which you can tell from the genetic marker?
That’s right. That line then became the “mother”, if you like, of everybody outside Africa. And then they started to split off. Some went down to Australia; some went up into Central Asia; some went up into Europe – carrying their own markers from that point. So it’s rather like the branches of a tree with the main trunk of the branch being in Africa.
Q: And the film shows this? Documents this?
It tries to tell the story in a dramatic way because we want people to understand the science but we also want people who aren’t particularly turned on by science to also be able to enjoy the film on an entertaining level and be involved in the story of “us.” We want people to be able to look at the screen wherever they are, whoever they are – whatever color they are, whatever creed they come from – to look at that screen and say this is our story. It’s not these strange people who lived thousands of years ago. This is a story of our forebears.
Q: Do you have a favorite part of the film, or a part that you consider especially important in the sense of what you want to convey to the viewer?
The part of the film that moves me most is the death of the little boy when he falls over and his father carries him and buries him. He died 44,000 years ago. From his skeleton we recreate that scene. It shows a caring side of humanity. This little boy was obviously damaged because he has a broken skull and he was laid very carefully in this recess a cave and was obviously buried with care and love and I think that a parent’s love for a child is what really the human race is about. And the only problem is, is that we don’t seem to be able to care that much about “other” people’s children.
Q: You’ve said that you’re not a scientist, and certainly not a specialist in this area, so how did you, the filmmaker, encounter this piece of science? How did you get engaged?
I read a book written by professor Stephen Oppenheimer who is the professor in this film. We are telling his synthesis. He’s the man who came up with the scientific end of this. I was talking with him about this other book he had written with the view of trying to make a film out of it and he told me this story that everybody outside of Africa comes from one small group and that everybody on the planet is related to one woman. And I thought that was just an extraordinary thing. And I said this would make a beautiful film, a lyrical film, which is what I wanted to do.
Q: Let me ask you again, getting back to the actual story, Why did this group of people leave in the first place? And where did they go?
Obviously that’s conjecture, but we believe that they were beach combing. And we have proof of modern humans beach combing along that particular coast of Africa about 80,000 years ago. At that particular time there was a major freeze up of the world and the world became much drier. And also because of the shallowness of the Red Sea that would have become very, very salty. So whatever they were eating while they were beach combing would have been dying off. Just across the water from where they were you have Yemen, which was at the time was being hit by some freak monsoon weather and it was very green and also it was on the ocean side, so the water wouldn’t have been so salty. It must have looked very tempting for them. Such a short distance away, green inviting hills. They were standing on this rather deserted desert lacking food. That’s why we think they made this trek across the water.
Q: And then from Yemen they go North, South…where?
From Yemen they went to the Gulf of Arabia which at the time was dry because sea levels were so much lower. The gulf was actually fresh water lakes; it wasn’t the gulf as we know it today. So it was a very good place for them to stop. Some of them went all the way round the coast all the way down to Australia and then all the way up the coast to China. Some of them went North of the Himalayas into Central Asia. Some 30,000 years after they got to the Gulf, they then went North into Europe because the weather changed again, opening up a green corridor from where they were in the Gulf up into Turkey. There was some wet weather that greened the desert. this is why they didn’t get into Europe until 50,000 years ago.
Q: This charting of the routes seems pretty precise.
Yes it is pretty precise. If you’re carrying a marker – up to a certain point if a population is carrying a marker up to a certain point – and then beyond that point that marker isn’t there you know which direction the people are moving. So you can say, well at this point there must have been a split because the marker then goes over there and the new marker happens over here. It’s a split in the branch; you have two more twigs.
This is what was so wonderful about the end of the film. You had two people from opposite ends of the world carrying the same marker. There was a Greek lady, Angela, who was a recent immigrant into America from Europe. And then there was a native American who was a full-blooded Cree. And we tested them and we found that they both carried quite a rare marker in their mitochondrial DNA which is called “X” for no other reason than that’s the letter that the scientists gave it. Now “X” first came into being in Central Asia about 30,000 years ago. So what it means is, that one of the daughters of our out of Africa “Eve” had a mutation that we call “X”. Her family then split. Part of her family went West towards Europe and part of her family went East toward Siberia and then on into America and became the Native Americans. So when Angela came to the United States from Europe and she met with Leonard in our laboratory it meant two members of the family were rejoined 30,000 years later.
Leonard was completely blown away. But it doesn’t change the fact that he is Native America. He can still be part of the first people of North America. We’re going back 30,000 years and we know that human beings didn’t get into North America until about 20,000 years ago so his family could have been part of that first group. What it does do is prove that we all come from the same place, that we’re all brothers and sisters. We really are, not just in a moral sense, but actually in a physical sense. People better get used to the idea.
It’s important to understand that this is taking place over thousands of years….
Thousands of years. You’re not talking about a couple of generations; you’re talking about 5,000 generations.
Q: And I assume that in addition to moving they are changing in the sense of physical characteristics in order to adapt to various climates that they find themselves in, and I suppose developing languages as well.
Yes, they are changing. Absolutely correct although they might well have had language before. In fact we know that they did because they possessed the hyoid bone which is a bone in the throat which enables us to talk. We know that Neanderthals and homo Erectus and early hominids had the hyoid bone so we know that they talked as well. So we had speech.
But we’re not talking about primitive people here.
Q: This is modern man.
This is modern man! One hundred and fifty thousand years ago this woman who was our genetic “Eve”, if you like, had all the capabilities that we have today. And all the potential. She was just like us! If we were to bring her to this time, educate her, dress her up and walk her down the street you would not know the difference. We are not talking about primitive early people who dragged their knuckles on the ground!
Q: Is this “new” in the sense of science? Is this a breakthrough or has this been around?
That aspect of it isn’t new. The early Mitochondrial Eve “mother” is not new. That has been around in scientific circles. But what is new is the out of Africa group that left once; the way they left which was the southern route across the mouth of the Red Sea, and also the movement from the Gulf into Europe 50,000 years ago. That is all brand new.
Q: Is it controversial?
It is controversial. But only because some people don’t like other people to get things right. But people are very very quickly coming to realize that this is something they can no longer argue with. Professor Stephen Oppenheimer, whose synthesis we filmed, was the first person to come up with these aspects because he looked at all the information, not just the genetic information. He looked at the oceanography, at the climate; he looked at all the things that were happening and came up with these explanations which have now been argued about for a little while but have held up.