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Neanderthal Genome, Arctic Ice Top Science Stories

December 29, 2006 at 6:30 PM EDT
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GWEN IFILL: New discoveries in science this year taught us much about the enormity of what we do not know about the past, the present, and the future, from the origins of space and the human race, to the evolution of the planet as we live on it today.

Three less-noted discoveries were eye-opening. Joining us to talk about them are John Rennie, the editor of Scientific American magazine, and Andrew Revkin, science reporter for the New York Times and author of the book “The North Pole was Here.”

John Rennie, I want to start by asking you about this really interesting discovery of the Neanderthal DNA. What was that? And how did they find that?

JOHN RENNIE, Scientific American: Well, back in November, two different research groups, one based in California and one in Germany, made reports on the first details we have about DNA that was extracted from the thighbone of a Neanderthal, from about 38,000 years ago.

The Neanderthals were a people — they were human beings — and yet they were a different species of person, really not the same as the modern humans that you and I are. And so this is something that a lot of biologists have been wanting to look at for a long time, because, within that genetic information, we hope, are clues to where the Neanderthals came from and just how closely related they may be to us.

GWEN IFILL: Andy Revkin, do we know whether these Neanderthals interacted with human beings as we know ourselves to be?

ANDY REVKIN, The New York Times: There is pretty good evidence that they did. It’s kind of a strange moment in history where you have a branch of evolution, a parallel universal, kind of, for this thing we call “humanness” that was going to fade out pretty quickly there.

That’s right in the depths of the last ice age when the last of the Neanderthals kind of were overlapping with the last of — I mean, the first — not the first — but that parallel group of homo sapiens that we all spring from.

GWEN IFILL: John, do we have any idea why the Neanderthals disappeared?

JOHN RENNIE: It’s still one of the big mysteries of paleoanthropology that way. There are questions that perhaps we, our type of human being, basically just out-competed them and they became extinct. There are questions of whether or not we interbred with the Neanderthals enough that they essentially disappeared that way.

Looking at this, the first take on this genetic information that we were getting in, it doesn’t seem that we interbred with the Neanderthals to any significant degree, although that’s still not certain, and, frankly, no one can entirely understand why that would be.

GWEN IFILL: Andy Revkin, let me ask you about climate change. That’s the big political debate. But there were actual scientific discoveries about that this year, in particular that the Arctic pole cap was melting. Say that right for me.

ANDY REVKIN: Well, the Arctic Ocean, which is an ocean with a thin sheet of floating ice on it, which I got to stand on a couple of years ago, is projected now — the latest computer simulations say that by 2040 in the summertime we could have a blue ocean on the top of the planet for the first time in many thousands of years, and maybe a lot longer than that.

And that’s kind of a momentous thought. All of our history — essentially, our lore and notion of the Arctic has been as an ice-locked, untouchable place. And the idea that you can sail to the North Pole easier than you could ski to it is a new idea.

GWEN IFILL: But even as the edges of the cap are melting, apparently there’s more snow at the center of the ice cap?

ANDY REVKIN: Well, on Greenland, which is this huge island just off to the side that borders the Arctic Ocean, it’s got a vast amount of ice banked up there. It’s 13,000 feet high. I also got to go to the summit of that ice sheet a couple years ago.

And there you have this competition between snow falling in the middle all the time and ice melting and cracking away from the edges and flowing into the ocean. The iceberg that sank the Titanic came from one of those Greenland flows.

And the new evidence this year is that there’s more ice leaving Greenland than accumulating as snowfall in the middle. And what that means is Greenland’s probably contributing more to the eventual rise in sea level that’s been projected in the next 100 years as the world warms.

GWEN IFILL: John Rennie, do we have any better understanding of why, to the degree to which human activity is causing this melting?

JOHN RENNIE: Unfortunately, everything that we’re gathering in terms of information is just confirming all of what the models have been telling us for some time.

The greenhouse gases that we contribute — particularly carbon dioxide, from all of our industrial activities, like burning coal — are going up into the atmosphere, and they help to trap that heat. And, unfortunately, that seems to be the culprit.

There’s less and less doubt that the increase in global temperatures that we’re seeing and the kind of melting that Andy is talking about, that that could be caused by anything except a human activity.

GWEN IFILL: And yet there seems — this doesn’t seem to have settled the debate, has it?

ANDY REVKIN: As I’ve been writing most of this year, the debate you see in the public realm in the media is most often at the edges of what science actually understands.

Unfortunately we, the media, are often attracted to the hottest voices in the room, and that basically comes down to someone saying there’s a real-time catastrophe on one side, and someone saying it’s all a hoax on the other.

But what John is pointing to and what I’ve been writing about a lot is that there is a very powerful middle here that science really understands, with more confidence than ever — and there’s a big report coming on this in February — that there is a human component to warming, that it’s getting more and more dominant, especially as China kicks into high gear in this century and dominates the greenhouse gas emissions that we kind of dominated for the 20th century, that we’re headed to a world that is going to be a transforming place, unless there is a lot done to change how we get our energy.

GWEN IFILL: John Rennie, I want to talk to you about something very mysterious, this other discovery, dark energy and dark matter, something we actually can’t see. So how do we know that it’s a discovery?

JOHN RENNIE: Well, it’s a good question. When we look around at the universe with our human eyes, pretty much everything we’re seeing — planets, stars, galaxies — that all is normal matter and energy, but that only makes up about five percent of what is out there.

Twenty percent of it seems to consist of some sort of invisible dark matter that must be made of something other than the kinds of atoms that we know that exerts a gravitational force that is helping to hold galaxies together.

And then 75 percent of the universe seems to exist of this even more mysterious force called dark energy, which is a kind of repulsive force that is pushing everything in the universe apart and making the universe expand faster and faster.

GWEN IFILL: Well, let’s do our part, Andy. If you had to look back on this year and the discoveries that were paid less attention to, would you say that we’ve raised more questions than we’ve answered?

ANDY REVKIN: My sense is we tend to pay attention to things that seem dramatic and powerful, and some of the big developments this year have been related to the slow drips, the issues that don’t get a lot of media attention.

Climate change is kind of the ultimate slow drip in some ways, but there was another very powerful thing that happened that really slipped past everyone, which is the extinction of the first whale species.

You know, this creature living for 20 million years in the Yangtze River, this Baiji dolphin vanished. They couldn’t find it in weeks and weeks of searching.

And that’s the kind of thing — extinction of species, for hundreds of years, has mostly been kind of out of sight and kind of invisible. And now it’s happening to very large creatures that are a very big part of our world. And that’s something that I think is — the message is the slow drips matter, at least to me.

GWEN IFILL: And, John, what do you think about the slow drips and the notion that there are questions which are raised which are as essential to science as the ones that are answered?

JOHN RENNIE: Well, I would agree with Andy that a lot of times — ultimately the most important things that happen in science are the ones that we’re not focusing our attention on a lot or sometimes are only peripherally related to them.

For example, the Neanderthal genome story that you mentioned, one of the technologies that made that possible was a new type of technology that hugely accelerates the rate at which we can take any kind of DNA and get the sequence for that.

Now, what that probably means is that, say, within another 10 years, it would mean that you or I or Andy or anyone else out there, we could actually have our own individual DNA completely sequenced for a thousand dollars or so.

And that could become a very important part of our medical records, for example, although there are going to be a lot of interesting questions about the security of that information, and the meaning of that genetic information that we’re all going to be coming to grips with.

GWEN IFILL: The year in science. John Rennie of Scientific American and Andrew Revkin of the New York Times, thank you both very much.

ANDY REVKIN: You’re welcome.

JOHN RENNIE: Thank you.

RAY SUAREZ: Since Gwen taped that interview, there were new developments on the global warming front. Scientists reported that a huge ice shelf broke away from an island in the Canadian Arctic. It was the largest break in nearly three decades, and the shelf itself was said to be bigger than the area of Manhattan Island. Geographers said they believe warmer temperatures played a major role in the break.