JEFFREY BROWN: The original search was for dinosaur bones, but at a site in Niger in the Southern Sahara, scientists came across the bones of an entirely different species: humans.
The site called Gobero contains a cemetery with some 200 graves with skeletons from two distinct populations, dating as far back as 10,000 years, some buried in ritual poses.
Artifacts such as jewelry and ceramics were found, as were harpoon tips and other fishing tools, evidence of a time when the Sahara was green and filled with lakes.
And joining us now is Paul Sereno, a University of Chicago professor and paleontologist who led the team. It was funded in part by National Geographic.
So you go looking for dinosaurs. Sometimes you go looking for something and you find something else?
PAUL SERENO, University of Chicago: You know, that's really part of discovery, maybe the best part, finding something unexpected.
JEFFREY BROWN: So this is an area, I gather, where it was known that long ago was lush. There was green; there was water. What's the surprise that you found here?
PAUL SERENO: Well, the surprise is that we get much more of the picture when you find hundreds of burials. You get entire bodies. You get stature. You get health. You really get a look at the lifestyle of these people. You get to understand what they were eating, what they're hunting.
And we actually found a cemetery. We found people that were buried at right about the same time. This was very unexpected in the middle of the Sahara. This is something we usually reserve for sedentary or stable people building pyramids and things like that.
But here, in the middle of the Sahara, we got a cemetery, a very interesting lifestyle. So that's really what we're getting out of this.
JEFFREY BROWN: All right, now, you brought two skulls. I don't usually get to say this sitting here at the NewsHour, but you brought two skulls to the table.
PAUL SERENO: They're three for the interview.
JEFFREY BROWN: What did they tell us about the kind of people? As I said, they were two different peoples at two different times, right? And these represent the two types?
PAUL SERENO: Yes, and this is really a fairly stunning part of the discovery that two very different kinds of people -- they're our species. They're 6,000 and about 9,500 years old.
But if you look at these faces a little bit more closely, these are two men, adult men, but very different faces. So we have squared orbits here that are separated, different shape to the nose, different shape to the chin, a lot of different shape to the back end of the skull. These are clues that they're really very different people.
We may get some genetics out of the teeth eventually to go along with the differences in skull shape, but this is what we use to really determine different human populations, populations that are separated in time.
JEFFREY BROWN: All right, so this is the older one, and they were tall?
PAUL SERENO: Very tall. This man here, we have his complete skeleton. He's sort of bundled up in a tube. You wouldn't know it from looking at him how he was buried how tall he is, but he's six-foot-five, and that's...
JEFFREY BROWN: Six-five?
PAUL SERENO: That's an average for the adult males.
JEFFREY BROWN: Wow.
PAUL SERENO: So they were very tall, the early population.
JEFFREY BROWN: And then the later ones, what year are we talking about here?
PAUL SERENO: About 6,000 years ago, this population -- we call them Tenerians. We call this Kiffian, and we call these Tenerians. Their average was below six feet. This man here stood a little bit below my height, about five-foot-six.
JEFFREY BROWN: Is it unusual to find two very different populations on the same site?
PAUL SERENO: Well, what we did in analyzing the skull shape of this individual and that individual is, first, show how different they are. And then, second, we linked across the Sahara populations from North Africa, the coast of the Mediterranean, all the way over to the Atlantic coast, an ancient population with this kind of skull.
So we see a migration into the Sahara, when it turned green, from those parts. And then they were driven out by a dry period. And when it turned wet again, another kind of person moved in.
Where these people came from, ultimately, and where they became the Tenerians, that's for future research. We're really interested, because the Sahara is inhabited today by some very interesting nomads. And we're wondering, ultimately, are we looking at the roots of that population?
JEFFREY BROWN: There's another photo that I want to show our audience. This is a finding from the cemetery of a -- well, you can describe it -- a mother and children?
PAUL SERENO: Yes, this is a remarkable, remarkable grave. There's really nothing been found in the fossil record, pre-historic record, anything like this.
It's a woman about 30 to 40 years of age reaching out towards two young individuals we presume to be her children. By the way, they're posed, very intimate pose, an 8-year-old and a 5-year-old. The 5-year-old is literally hugging the 8-year-old, reaching for the woman.
We found pollen clusters, evidence of flowers that were laid down underneath these burials, and arrowheads that were tossed into the grave before they were ceremoniously buried.
But emotion, a sincere intimacy that -- the human feelings that you get from this grave -- we brought it back exactly as we found it, 5,300 years old.
JEFFREY BROWN: Now, one of the themes then -- climate change -- is very topical now. So what connections do you make?
PAUL SERENO: It's really stunning. Elephants, hippos, crocodiles, six-foot fish in the middle of the Sahara.
JEFFREY BROWN: In a place that now is all desert.
PAUL SERENO: It is not just desert; it's a desert within a desert. That's how they describe the Tenera. I mean, bone dry, hyper arid. And this is -- 5,000 years ago, things became drier and drier. We're talking just 5,000 years.
Humans didn't do that. Little wobbles in our Earth's orbit are the driving factor, ultimately, for these kinds of climate change, but climate change it is. And it really affected the populations that lived there. It really drove some out and allowed some others to colonize the place. It drove human history.
JEFFREY BROWN: And just briefly, you said what is coming next, in terms of some of the research. You're going to be involved? What happens?
PAUL SERENO: Oh, we're interested in fine-tuning our understanding.
I mean, basically, we want to know how the recent populations -- everybody wants to know how the recent populations relate to these ancient populations. Are we looking at the roots of the people who are living there today, the Egyptians, the Berbers, the Tuaregs?
And where do they come from? And, ultimately, we're interested in human history. And we have a much better view of the humans today that lived in the center of the Sahara than we did before we ran into that site.
JEFFREY BROWN: All right, Paul Sereno, thanks very much.
PAUL SERENO: You're welcome.