Ancient Migrations, Summer Sea Ice, and Archaeological Algorithms
Scientists have long known that humans originated in Africa. From there, our species migrated to Europe and Asia, but the details of that journey are less clear. This week in the journal Nature, three groups of researchers filled in a small piece of that puzzle. Annalee Newitz, the tech culture editor at arstechnica.com, describes the genetic clues that point to a single migration out of the continent.
Annalee Newitz is a science journalist and author based in San Francisco, California. They are author of The Future of Another Timeline and co-host of the podcast Our Opinions Are Correct.
IRA FLATOW: This is “Science Friday.” I’m Ira Flatow. We’ve known that the human species originated in Africa. The “Out of Africa” theory says that we started in Africa, and from there made our way to Europe and Asia. But the details of how we made that trip, well, the details are less clear.
Three different groups of scientists unlocked a small piece of that puzzle, and their work was published this week in the journal Nature. Here to tell us the details of those studies is Annalee Newitz. She’s the tech culture editor for “Ars Technica,” based out of San Francisco. And joins us here at KQED. Welcome.
ANNALEE NEWITZ: Thanks, nice to be here.
IRA FLATOW: So there are lots of studies looking at the origin out of Africa. How are these studies different?
ANNALEE NEWITZ: Well, one of the things that’s really great about these studies is that two of them look at modern day people’s genomes to kind of trace back the diversity that we see today to an origin point. And what they did was they looked at Aboriginal Australians and people in Africa whose genomes have not really been sequenced very much. We have a lot of coverage in Europe and Asia.
So this gives us a much better picture of global genetic diversity. And so once we have that, we can actually walk backward and trace it to an origin point. And what they found– this is the other piece that’s very interesting– is that it seems that much everyone on earth can trace their ancestry back to one migration out of Africa that happened somewhere between 80,000 and 50,000 years ago.
So we’re talking, basically, anyone you meet on earth, whether it’s someone from Australia or someone from the Americas, they are related to you.
IRA FLATOW: Wow. And do we know which direction they first went when they went out of Africa?
ANNALEE NEWITZ: So we don’t know for sure. One of the other studies looked purely at that question and examined how the climate had changed, particularly passages out of Africa into the Middle East, and how wet it would have been. So could people, lots of people, have left and actually found food and found decent places to live that weren’t just super dry desert?
And the times when it was much wetter and would have supported life kind of coincide with this window, this 80,000 to 50,000 year window. Not completely, so there’s still a lot of room for debate here. Plus, on top of that, we know for certain that there’s evidence that people did leave Africa before that time too. So there were already groups of archaic humans in Asia and in Europe.
And so this big mob of immigrants coming out of Africa would have met those people. And we still don’t really know what happened to them. There’s some hints, but we’re still not sure.
IRA FLATOW: So there were like three studies then? There was more than one study.
ANNALEE NEWITZ: Right. There were three studies, two of which looked at genetics and one of which looked at the climate that would have allowed people to leave Africa during that time.
IRA FLATOW: So if we had our genetics– all genetics done together, we’d see that there’s some commonality.
ANNALEE NEWITZ: That’s right. Basically, all of us are descended from a big group of immigrants who came out of Africa.
IRA FLATOW: We’ll have them over for dinner on Sunday.
ANNALEE NEWITZ: Have a family reunion.
IRA FLATOW: Let’s talk about the summer. This summer has not been so good for Arctic sea ice. There’s so little of it now that the first luxury cruise liner passed through the Arctic this month and made it safely to New York.
ANNALEE NEWITZ: That’s right. They took the Northwest Passage and went through a bunch of incredibly vulnerable ecosystems in this area. And this past summer, we’ve just reached our glacial minimum. And so there’s now 750,000 square kilometers of ice, which makes it the second smallest chunk of ice that we’ve had. The smallest was in 2012.
So as I said, this is a vulnerable ecosystem. But at the same time, as the ice shrinks and we see this pattern where it’s shrinking more and more, we are going to see much more activity in shipping lanes. And there’s several nations that lay claim to the areas that these ships might pass through. So this is going from being an environmental issue to a kind of geopolitical issue.
IRA FLATOW: Right. You know, I’ve always said that if you want to know the truth about something, you follow the money. And for people who don’t yet believe in global warming, the fact that all these businesses are investing so much money now in cruising and sending shipping through there shows you how much they believe it.
ANNALEE NEWITZ: Yeah, it’s true. And the fact that we did have this luxury liner go through, it’s kind of opening up the way, first for tourism, and now I think the next stage we’re going to see is we’ll look to find out– I’m very curious to find out. Apparently, Canada and Denmark have already been arguing over who owns what.
IRA FLATOW: Well, the Russians have planted a flag at the North Pole, under water.
ANNALEE NEWITZ: Yeah.
IRA FLATOW: They say, we own this. And there’s, you’re right, a very big geopolitical battle going on.
ANNALEE NEWITZ: Yeah. And Norway is in there too. So we can look forward to US versus Norway.
IRA FLATOW: Not just in hockey. Let’s finally– Indiana Jones is getting high tech. Archaeologists deciphered– this was really cool– an ancient scroll by what, x-rays, an algorithm, or what did they– they peered inside this scroll without opening it.
ANNALEE NEWITZ: Right. This scroll’s called the Ein Gedi scroll. And it’s sort of roughly from the same place as the Dead Sea Scrolls. It’s about 1,700 years old. And basically, what they did was they used a micro CT scan to look into the scroll that had been burned and crushed. It was just– it basically looked like a lump of coal.
And a micro CT scan is just like a CT scan you get at the hospital, but it’s just very high resolution. So they created this high resolution 3D image of what was inside that burned lump. And they used computer algorithms to reconstruct the surfaces of the pages.
So imagine a crumpled piece of paper, and trying to figure out where the surfaces are. And once they knew where the surfaces were, they were able to actually find the points where ink had been put on those pages. And they deciphered it. And they found out it was the first two chapters of Leviticus in Hebrew.
IRA FLATOW: And so they could read it by first defining the pages, and then because the ink is made out of something, they could trace the ink in it?
ANNALEE NEWITZ: Right. It was made somewhat easier because the ink contains some metals. But theoretically, any ink should be visible. And it’s just, once you find the surface of the paper, then you look at the text– it’s not paper, of course. It’s parchment, which is made of animal skin. And then you look at the texture of it and you can actually find the ink itself.
So the researchers who worked on it say that soon they’re going to be able to do this even if it doesn’t have metal in the ink. So they should be able to maybe read some of the other Dead Sea Scrolls and some other artifacts.
IRA FLATOW: Or read something that you think you might have burned.
ANNALEE NEWITZ: That’s right. Yeah.
IRA FLATOW: You know who is looking at this now.
ANNALEE NEWITZ: That’s right. And in fact, the researchers mentioned that the intelligence community has expressed a lot of interest in this, because imagine what you could do. You could read information that was in an envelope. If someone decided to burn evidence, now there’s a possibility that you can read it. So there’s a lot of implications beyond archeology for this.
IRA FLATOW: Wow, that’s fascinating. Thank you, Annalee.
ANNALEE NEWITZ: Thanks for having me.
IRA FLATOW: Annalee Newitz is the tech culture editor for “Ars Technica” based right here in San Francisco.