Friday, 15 February 2013
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Monday, 11 February 2013
Next Time Your Mom Says Don't Go Out in The Rain, Spray Yourself With This
OK, this is an ad. I can't vouch for it. I'm almost embarrassed to be showing it to you. But you have to take a look. When I saw it yesterday, I had to pick my jaw off the floor. This product, called "Ultra Ever Dry" is a nano-tech coating you can spray on any number of different surfaces, shoes, cinder blocks, coats. (Your hands? Probably not.) It's superhydrophobic (it repels water) and oleophobic (repels hydrocarbons) — but words don't do it justice.
What is it? The company says it's a "coating" that will repel almost any liquid by creating a barrier of air on the surface. They don't say what's in the coating. Whatever it is, the How to Apply This Product video suggests you don goggles, gloves and protective gear when you spray. They claim it will protect in temperatures ranging from -30 degrees Fahrenheit to 300 degrees Fahrenheit, but durability is a question. In the video, they say abrasion might affect performance (which makes me wonder how long a pair of sprayed boots would stay dry if you were on a wet, slippery, rocky hiking trail). It's expensive. The base coat is $57.95 and the top coat is $100.95 a quart. On the other hand, if you dare to spray it on your car windows, you wouldn't need window wipers. Or would the windows get too cloudy? If you sprayed it on a car surface, would it affect the gloss? Probably.
I have so many questions.
Trolling various Internet sites, I found crazier questions, some of them sci-fi delightful. A guy wondered what would happen if he coated his boat with this stuff. If water is no longer a drag on your forward motion, maybe his boat would shoot through the water like a rocket. He wanted to try it. But when he wrote the company, they warned that at fast speeds, with less drag, "overall stability" might be affected. Meaning he'd get dunked.
Which raises another question. What if you coated yourself with this stuff and dove into a pool? Surrounded now by a thin coat of air, would you sink? Struggle? Hmm, thought one commenter, "Probably you get ejected from the pool." Whooosh!
Nanotechnology is starting to get interesting.
I realize we don't have a lot of information about this product, not yet, and we may discover after a few months in general use, it turns out to be pretty basic water-resister, not unlike many products already on the market, in which case, my hat goes off to whoever wrote and shot that video. There's an art in getting people excited and curious. After all, consider the greatest ad ever, ("It picks up pinecones!") for a garden tool called the "Wonder Rake 5000":
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Automakers Drive Towards Hydrogen Cars
Toyota and BMW have formed an alliance to work on fuel cell cars. So have Daimler, Ford, and Nissan, with hopes of having cars on the road by 2017. But why now, and what obstacles still stand in the way? Jennifer Kurtz discusses the current state of hydrogen fuel technology.
Copyright © 2013 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.JOE PALCA, HOST:
This is SCIENCE FRIDAY. I'm Joe Palca, sitting in for Ira Flatow. This is SCIENCE FRIDAY. I'm Joe Palca, sitting in for Ira Flatow. Later in the hours, digital privacy and dating the demise of the dinosaur, that's a lot of D's. But first, last week, Daimler, Ford and Nisson announced an alliance to work together on hydrogen fuel-cell technology for their passenger vehicles. That follows on the heels of a similar announcement last month from Toyota and BMW. Other major automakers have signaled that they're fuel cell, too.
But where does the technology stand now, and what needs to be done to make the carmakers' hopes of getting tires on the road by 2017 a reality? What obstacles still stand in the way? That's what we're talking about first this hour. So give us a call. Our number is 1-800-989-8255, that's 1-800-989-TALK. If you're on Twitter, you can tweet us your questions by writing the @ sign followed by scifri. If you want more information about what we'll be talking about this hour, go to our website, www.sciencefriday.com, where you'll find links to our topic.
And now I'd like to introduce my guest. Jennifer Kurtz is a senior engineer and the leader of the Technology Validation Group in the NREL Fuel Cell and Hydrogen Technologies Program, part of the National Renewable Energy Laboratory in Colorado. Jennifer Kurtz, welcome to SCIENCE FRIDAY.
JENNIFER KURTZ: Thank you, Joe, and I'm happy to be on the program today.
PALCA: Oh, that's great. So you've - I mean, what have you been doing with these cars over at NREL? What's been the last few years? Have you been driving them? Have you driven them?
KURTZ: Yeah, in fact I was driving a fuel-cell vehicle this morning. We went out and got some bagels for our center to celebrate the interview today.
PALCA: So is it a different kind of experience? Do you feel like you're not driving - I mean, is it different from a normal car, You know, the cars we're used to, internal combustion?
KURTZ: Yeah, no, the car has some unique characteristics, one of them being zero tailpipe emissions. It's quite quiet. But, you know, once you start driving the vehicle, it's really easy to forget that you're driving fuel-cell vehicle. It's just like a standard, traditional driving experience.
And since we had visitors on site, we had five adults in the vehicle. It was very easy to carry a conversation. And it becomes just a standard mode of transportation.
PALCA: So do they look any different from other cars, or can you put a fuel-cell engine into any - or a fuel-cell-equipped engine into any kind of car?
KURTZ: You can use any car, actually. We have - the vehicles that we've analyzed, they range from compact sedans all the way up to SUVs.
PALCA: So what's the advantage, do you think, of using a hydrogen-powered, full-cell-driven, fuel-cell energy care over, say, you know, one that you just plug in?
KURTZ: Well, for the fuel-cell vehicle, the zero tailpipe emissions is one key aspects. These vehicles can be filled in three to five minutes, and right now there are hydrogen stations available 24/7 and have very traditional retail-style filling capabilities. Vehicles - excuse me.
PALCA: No, go ahead. I was just going to ask, you said that there are filling stations available, but that made me wonder, you know, if I'm driving across the country, could I make it? I didn't think there were so many of those.
KURTZ: No, not across the country. The hydrogen stations, as well as the vehicle deployments, are very targeted right now, and that - so that the investments are not spread too thin. So for instance California, Hawaii, the Northeast all have focused activities in fuel cell and hydrogen deployment.
So for instances there is a pipeline station in Southern California. You can drive up and fill up. It looks very similar to a traditional gasoline pump. And fill your vehicle quickly and drive off. And with the vehicles, we validated a 250-plus-mile range on the vehicles we've analyzed. We've also participated in an on-road driving evaluation in collaboration with Toyota and Savannah River National Laboratory.
The results of that evaluation was a possible 431-mile on-road range. So range is another key aspect of fuel-cell vehicles.
PALCA: Right, so is that - I mean, we talked at the beginning, I said at the beginning about the obstacles. Is getting that kind of hydrogen infrastructure or the fueling infrastructure in place something that's one of the roadblocks to getting these cars on the road more widely?
KURTZ: Yes, that is a challenge. And one of the ways that we're working on that challenge is through highly collaborative relationships between automakers, energy industries and government, and that's state and federal government. So these activities include working groups to identify how to make the investment in stations.
It's also looking at scenario analyses so that we can understand risks with station deployment and really look at market and regulations and policies to help make sure that we're putting early stations in or the next generation of stations in key areas.
PALCA: Well, let's take a call from one of our listeners. We've got quite a few. And let's go first to Molly(ph) in Hillsboro, California. Molly, welcome to SCIENCE FRIDAY.
MOLLY: Hi, thank you. I was wondering two things. First, I'm wondering about the safety in terms of accidents on the road, it being hydrogen and all, and the second thing is I was wondering if there are plans in place to keep the manufacture and such in America.
KURTZ: Yes, so with regard to safety, the vehicles that we've analyzed through the support of the Department of Energy Fuel Cell Technologies Office, has had a very strong safety record. Safety is a key aspect to the vehicle and station deployment. It includes things like hydrogen sensing, alarms, control strategies to make sure that if there is a situation that the systems are shut down appropriately and quickly and safely.
Traffic accidents are common. With hundreds of fuel-cell vehicles on the road, we've actually some fuel-cell vehicles that have been in non-related hydrogen accidents. All onboard safety mechanisms reacted appropriately, and we didn't see released hydrogen.
And just from my personal perspective, I feel completely safe driving a hydrogen fuel-cell vehicle around, having my family and the people that I love in those vehicles.
PALCA: And I don't suppose you really have that much to say, Jennifer Kurtz, about whether or not these cars are built in America.
KURTZ: Well, you know, it's - you know, it's certainly an international effort. We've got the - just the OEMs that you mentioned at the beginning of the program. They're - it's international. So we do have deployments in the United States, and you're exactly right. In terms of manufacturing, that's outside of my spectrum.
PALCA: Yeah, let's take another cal now and go to Matt(ph) in Rockford, Illinois. Matt, you're on SCIENCE FRIDAY.
MATT: Hey, hello there, how are you guys doing?
PALCA: Great.
KURTZ: Great.
MATT: I have a question for you in regards to electrolysis and type of a hybrid fuel-cell vehicle. I've created a little HHO system run my whatchamacallit, my lawn mower. It seems to work. I cut the consumption in pretty much half. I've seen people on the Internet do the same things for their trucks, except they just purely run off of electrolysis, the HHO systems. Would you guys ever consider doing something like that?
Because I know the hydrogen systems that you guys are talking about, the infrastructures, you know, implement the stuff would be, you know, amazing in the cost it would take for the taxpayer to put up with the bill.
KURTZ: Well, how about we have a - there are a number of ways to produce hydrogen. And we have four fuel-cell vehicles on loan at NREL's campus fom Toyota. Our hydrogen is actually produced through electrolysis that's powered by wind and solar.
So a colleague has stated our fuel-cell vehicles are driving around today based on hydrogen produced from wind that blew last week. So that's an example of an exciting way to produce hydrogen. There's also an example a trigeneration system right now in Southern California at a wastewater treatment facility.
This facility or this system uses biogas to fuel a fuel cell, and it co-produces heat, power and hydrogen for light-duty fuel-cell vehicles. So there are a wide range of possibilities and ways to produce hydrogen right now that are being worked on.
PALCA: So I've been wondering, you were talking earlier about the safety of these systems. I heard a very interesting lecture some weeks ago about these solid-state systems, some sort of a solid material that couldn't explode, that would be recharged, and you would sort of move it in and out, not really just a gas tank of hydrogen but something a little different. Do you know about those?
KURTZ: Well, my area of expertise is looking at and validating fuel-cell vehicles that are on the road today. Those fuel-cell vehicles are using compressed gasses, as you mentioned. Most of the vehicles are at 700 bar pressure. And so we've seen very strong safety records with those tanks. I think, as I mentioned, I feel comfortable with those fuel-cell systems and that onboard hydrogen storage system.
PALCA: So is there one thing at this point that you think is a barrier to getting these cars on the road? Is there something that - I mean, what would prevent it, for example, from making it by 2017?
KURTZ: Well, I think there are challenges that are being worked on. We talked about hydrogen infrastructure. I would say cost and durability are also two challenges remaining. I think what we've seen is a progression in terms of technology development.
For instance the vehicles that we looked at very early on, so this would be approximately 2003 technology, within the last decade, the range was - we've seen improvement in range, in freeze capability, in durability. And we've also - DOE has funded projects that have seen 80 percent cost reduction in fuel-cell systems.
We think with the partnerships, the investments that are being made by private industry, as well as government, will continue to see costs come down. But we certainly need to leverage economies of scale and investments across the board.
PALCA: Well, I'm wondering: What are costs? I mean, is this car going to be - are these first cars going to be comparable to what a standard car is going to cost, or are they going to be a lot more?
KURTZ: In terms of specific costs, I don't have the answer for you.
PALCA: Of course not.
KURTZ: But we have seen with all advanced vehicle technologies that there is a price premium associated with those technologies. So I expect that to be the case. But the partnerships, the recent announcements by the automakers have identified cost as a key area for development, whether they're looking to go in terms of the production scale.
For instance Hyundai has also announced recently they've kicked off their series production of up to 1,000 fuel-cell systems. So we should see in each phase of the deployment and wide-scale commercialization, or working towards wide-scale commercialization, that those costs won't come down.
PALCA: OK, well, we'll have to leave it there. We've run out of time. Jennifer Kurtz is a senior engineer and the leader of the Technology Validation Group in the NREL Fuel Cell and Hydrogen Technologies Program, part of the National Renewable Energy Laboratory in Colorado. Thanks for joining me today.
KURTZ: Well, thank you very much for having me on.
PALCA: And when we come back, digital privacy. Do you own any of your personal data? We'll be right back after this short break.
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PALCA: This is SCIENCE FRIDAY from NPR.
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PALCA: This is SCIENCE FRIDAY from NPR.
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Blocking Iran With A Global Game Of Nuclear 'Keep Away'
Iranian President Mahmoud Ahmadinejad (center) visits a uranium enrichment facility in Natanz, Iran, in 2008. Enriching uranium requires many fast-spinning centrifuges, arranged in what's called a cascade.
Iranian President's Office/AP Iranian President Mahmoud Ahmadinejad (center) visits a uranium enrichment facility in Natanz, Iran, in 2008. Enriching uranium requires many fast-spinning centrifuges, arranged in what's called a cascade.Iranian President's Office/AP
Iran's government on Thursday made clear it has no interest in direct talks until the U.S. eases sanctions that have been squeezing Iran's economy. But the Obama administration isn't budging and says the ball is in the Iranians' court.
The suspicion that Iran wants to make a nuclear weapon is the rationale for the sanctions as well as for veiled threats of U.S. or Israeli military action if those sanctions fail.
Iran's perceived nuclear aspirations are also the subject of a global effort that keeps popping up in the news: the game of "nuclear keep-away" to keep Iran from buying or manufacturing centrifuges, the machines that make uranium suitable for a bomb.
"We call it the long pole in the tent," physicist David Albright, a former United Nations weapons inspector, tells All Things Considered host Robert Siegel. "Getting the wherewithal to make the weapon-grade uranium or the separated plutonium is harder than learning how and assembling everything you need to know to make the nuclear weapon itself."
Separate Your Isotopes
Most uranium is useless for nuclear fuel or weapons. Less than 1 percent of it is the light, radioactive isotope uranium-235 that's used for power plants and bombs.
Close Shave: Asteroid To Buzz Earth Next Week
This computer image from a NASA video shows the small asteroid 2012 DA14 on its path as it passes by Earth on Feb. 15.
NASAAn asteroid the size of an office building will zoom close by Earth next week, but it's not on a collision course, NASA says.
Still, some people think this near-miss should serve as a wake-up call.
"It's a warning shot across our bow that we are flying around the solar system in a shooting gallery," says Ed Lu, a former astronaut and head of the B612 Foundation, a nonprofit dedicated to protecting humanity from asteroids.
The asteroid known as 2012 DA14 was first spotted last year by astronomers in Spain. It's thought to be about 150 feet across and made of rock.
It will whiz past Earth on Feb. 15, going about 5 miles per second. At its closest approach, it will be only about 17,200 miles above the surface of our planet. That's far nearer to us than the moon, and even closer than some weather and communications satellites.
NASA officials say this event is one for the record books — the first time scientists have been able to predict something so big coming so close.
"There really hasn't been a close approach that we know about for an object of this size," says Donald Yeomans, manager of the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
It will come closer than satellites in a geosynchronous orbit around 22,000 miles up, but is extremely unlikely to hit any of those as it goes by.
"This asteroid seems to be passing in the sweet spot between the GPS satellites and the communications and weather satellites," Yeomans says.
Animal Magnetism: How Salmon Find Their Way Back Home
Bright red sockeye salmon swim up the Fraser River to the stream where they were hatched.
Current Biology, Putman et al.
Bright red sockeye salmon swim up the Fraser River to the stream where they were hatched.Current Biology, Putman et al. Before they end up filleted and sautéed on your dinner plate, salmon lead some pretty extraordinary, globe-trotting lives.
After hatching in a freshwater stream, young salmon make a break for the ocean, where they hang out for years, covering thousands of miles before deciding its time to settle down and lay eggs in their natal stream.
So how do these fish find their way back to their home river?
According to one theory, it's all about magnetism. When salmon are young, the theory goes, they imprint on the pattern of the Earth's magnetic field at the mouth of their native river. Years later, when the salmon head back home to spawn, they home in on that pattern. In a study published Thursday in Current Biology, the scientists behind that theory now say they have evidence that's exactly how the fish are navigating.
Magnetic detection "is one part of their toolkit for being really efficient navigators," says the study's lead author, Nathan Putman, a postdoctoral researcher at Oregon State University in Corvallis. The fish also use their sense of smell to help them locate the exact stream of their birth.
The finding could be helpful for fishery managers who'd like to predict where their fish will be and how their populations might change due to climate change and fishing pressures, Putman says.
Around the world, many salmon stocks are on the decline, and scientists would like to explain odd events, like why millions of wild sockeye salmon didn't return to Canada's Fraser River in 2009. It's possible a glitch in the salmon's navigational abilities played a role.
An even bigger concern is whether being raised in hatcheries somehow alters salmon's "internal GPS." Spawned in tanks, these salmon are released into streams and rivers and account for a large amount of the "wild" salmon that swim in the ocean and end up on your dinner plate.
Putnam worries that something about their hatchery upbringing could throw off how these salmon perceive magnetic fields. Because the Earth's magnetic field is relatively weak and can be overpowered by man-made objects, it's possible that something as simple as the iron reinforcements in the fish tanks, or nearby electrical cables, could throw off the salmon's magnetic imprinting.
"Then they might not be very good at navigating, and that could cause problems," he says.
If salmon born in hatcheries get lost on the way back home, they could end up in the wrong stream and interbreed with wild salmon populations. That's a problem, because studies suggest that hatchery-raised salmon aren't nearly as good at surviving outside captivity as their wild counterparts — and when they mate, the wild stock ends up genetically weaker.
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Fresh Clues In Dinosaur Whodunit Point To Asteroid
Some 66 million years ago, about 75 percent of species on Earth disappeared. It wasn't just dinosaurs but most large mammals, fish, birds and plankton. Scientists have known this for a long time just from looking at the fossil record. If you dig deep enough, you find lots of dinosaur bones. And then a few layers up, they're gone.
But scientists couldn't figure out exactly what had caused this phenomenon. Of course, there were lots of theories.
"Some of them are pretty wacky," says J. David Archibald, an evolutionary biologist at San Diego State University who wrote the book Dinosaur Extinction and the End of an Era. "The really weird ones, of course, are that space hunters came and killed them all off, they died of constipation, mammals ate their eggs."
Then, in 1980, a new theory surfaced.
"It's the one that everybody hears about all the time because it's most dramatic," Archibald says.
Near what is now the town of Chicxulub in the Yucatan Peninsula, an asteroid more than 5 miles across slammed into the Earth. It caused tsunamis and earthquakes, and threw up a cloud of dust that smothered the world.
It sounds like a movie premise, but the Chicxulub impact left behind evidence. It threw up small blobs of black glass that were later found in Haiti. It dusted the world with iridium, an element that is rare on Earth but common in meterorites. It left a barely detectable imprint on the Yucatan Peninsula. Many scientists came to believe that the Chicxulub asteroid alone killed off the dinosaurs — and the public ate it up.
"We have this thing for big glitz and dramatic things," Archibald says. "Instantaneous is better."
But Princeton professor Gerta Keller wasn't convinced. She has her own theories about the mass extinction.
"Vulcanism has played a major role," Keller says.
In the hundreds of thousands of years before the Chicxulub impact, volcanoes in a region of India known as the Deccan Traps erupted repeatedly. They spewed sulfur and carbon dioxide, poisoning the atmosphere and destabilizing ecosystems. Keller says the dinosaurs were already on death's door by the time the asteroid hit.
And there is confusion about when that actually happened.
"If [the impact] is the cause, it had to be precisely at the time of the mass extinction," Keller says. "It can't be before and it can't be afterwards."
Geochronologist Paul Renne collects 66-million-year-old volcanic ash from a coal bed near Hell Creek, Mont.
Courtesy of Courtney Sprain
Geochronologist Paul Renne collects 66-million-year-old volcanic ash from a coal bed near Hell Creek, Mont.Courtesy of Courtney Sprain Keller's data suggest that the impact happened about 100,000 years before the mass extinction. Previous studies, on the other hand, put it 180,000 years after the dinosaurs died off.
Enter Paul Renne, a geologist from the University of California, Berkeley. To pin down the date, he headed out to the badlands of northeastern Montana.
"It's a region that has yielded a huge number of dinosaur fossils over the years," Renne says. "It's very famous for that."
Renne collected samples of ash that were deposited at the time of the mass extinction just above that treasure trove of fossils. He also obtained some of the glass blobs left by the Chicxulub impact. Measuring the rate of decay of radioactive potassium from these two samples, Renne was able to estimate the age of the impact and the age of the extinction.
"And lo and behold they are exactly the same," Renne says. "The impact clearly occurred right at the extinction level."
His results are published in the journal Science. They reinforce an idea that many scientists have held for years: The Chicxulub asteroid was the straw that broke the dinosaurs' back.
Gerta Keller thinks Renne's method was admirably precise, but she doesn't agree with some of his conclusions. She says his data are contradicted by other samples from Texas where a similar age date shows the Chicxulub impact predates the KT boundary — the point in time between the Cretaceous and Tertiary periods when the dinosaurs are believed to have gone extinct.
Still, there is one thing that Keller and Renne agree on: The asteroid isn't the whole story.
"There were significant extinctions and ecological perturbations going on a million or 2 million years before the impact, so we think that something else was already happening," Renne says. "What caused those things? There is an outstanding candidate — the early eruptions of the Deccan Traps."
The next step will be to find the age of these eruptions.
"We need to be able to place that set of eruptions into a time framework," Renne says.
Then they can better piece together what happened to the dinosaurs — and the rest of the species that went extinct. Renne and Keller will join Archibald and dozens of their colleagues at the Natural History Museum in London at the end of March to talk over their ideas.
"I'm looking forward to rather spirited discussions," Keller says.
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Penguin Poop Leads Ice Researchers To Unknown Colony
In 2009, a team of researchers from the British Antarctic Survey were studying satellite images of the Antarctic when they noticed something interesting: trails of penguin poop. That showed signs of a huge emperor penguin colony.
The existence of the colony was unconfirmed until a team of researchers from the International Polar Foundation visited in December 2012.
Alain Hubert, founder of the International Polar Foundation, was one of three researchers from the foundation's Princess Elisabeth Antarctica polar research station to visit the 9,000-strong colony of penguins on Antarctica's Princess Ragnhild Coast.
"When you arrive, they just come to see you, to watch you, to turn around you," he tells NPR's Neal Conan. "The penguins — and especially the emperors — they are so human. They're so cute."
Since the penguins had never encountered humans, Hubert says they weren't scared, just curious.
Hubert and his team live at the research station during the Antarctic summer and are focused on studying climate change, not penguins. After they encountered a number of emperor penguins, they were convinced that a colony must be close by. They decided to make the treacherous 30-mile trip east to the sea ice.
"First of all, you have to imagine you're in the middle of nowhere — without any visibility, with complete whiteout after 24 hours driving on the ice — you go down to the sea."
After navigating their way to the sea, they searched for hours and found more penguins than they had ever imagined. Hubert says that seeing so many animals huddled together was like being on another planet.
"I spent more than five years of my life in the polar regions, but that was the kind of moment that I wouldn't have expect[ed] to be able to ... just enjoy," Hubert says. "It's a privilege."
If there was enough penguin poop to see from space, it seems like there would be quite a stench on the ground. Hubert says it wasn't a problem.
"It's too cold, really, to smell it, you know?" Hubert says. "I spoke to some scientists ... and they told me if it was a bit warmer, it's really smelly."
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Science of Slumber: How Sleep Affects Your Memory
Robert Stickgold, Director, Center for Sleep and Cognition, Harvard Medical School
Ken Paller, Professor, Department of Psychology, Northwestern University
Matthew Walker, Principal Investigator, Sleep and Neuroimaging Laboratory, University of California, Berkeley
David Dinges, Chief, Division of Sleep and Chronobiology, Perelman School of Medicine
Michael Silber, Co-director, The Center for Sleep Medicine, Mayo Clinic
We spend a lot of time sleeping (roughly one-third of our lives, according to the National Institutes of Health). But how much downtime do our brains really need? Experts discuss the links between sleep, memory and cognition, and why our sleep patterns change as we age.
Copyright © 2013 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.JOE PALCA, HOST:
This is SCIENCE FRIDAY. I'm Joe Palca, sitting in for Ira Flatow. If you add it up, we spend a lot of time sleeping, about a third of our lives, actually, and it turns out our bodies don't just power down as we slumber. Research is showing that sleep plays an important role in how our brains process and store the information that we learn throughout the day.
A study published in last week's edition of the journal Nature Neuroscience looked at how sleep patterns change as we age and how those changes affect our memories. The researchers found that as we got older, as we get older, the quality of our sleep deteriorates, and so does our ability to remember newly learned information.
So how much rest does your brain really need, and what does it do with that rest once it's getting it? We're talking about the science of sleep this hour. We want to hear from you. Maybe you have some theories about what the brain is doing while you're asleep. We'd like to hear about that. Give us a call. It's - the number is 1-800-989-8255, that's 1-800-989-TALK. And if you're on Twitter, you can tweet us your questions by writing the @ sign followed by scifri. If you want more information about what we will be talking about this hour, go to our website, www.sciencefriday.com, where you'll find links to the topic.
And now let me introduce my guests. First we have Matthew Walker, he's an associate professor and principal investigator of the Sleep and Neuroimaging Laboratory in the Department of Psychology at University of California, Berkeley. He's co-author of the study published last week in Nature Neuroscience, I guess it was actually a review article. He joins me from a studio in Berkeley, California. Welcome to the program.
MATTHEW WALKER: Thank you very much for having me.
PALCA: Also we have Robert Stickgold is associate professor of psychiatry and director of the Center for Sleep and Cognition at Harvard Medical School and the Beth Israel Deaconess Medical Center in Boston, Massachusetts. He joins me by phone today. Welcome.
ROBERT STICKGOLD: Hi Joe.
PALCA: And you're still able to see - you're still aboveground there, the snow hasn't come to the roof of your house?
STICKGOLD: I can see all the way out to the street.
PALCA: OK, well that's good. Well have an update at the end of the hour. Next is Ken Paller, he's a professor of brain, behavior and cognition in the Department of Psychology at Northwestern University. He joins me from a studio in Evanston, Illinois. Welcome to the program.
KEN PALLER: Thank you, Joe.
PALCA: And we also have Michael Silber, he's a professor neurology and co-director of The Center for Sleep Medicine at the Mayo Clinic in Rochester, Minnesota. He's also pas president of the American Academy of Sleep Medicine. Welcome to you.
MICHAEL SILBER: Thank you, pleasure to be here.
PALCA: So we have a lot of people and a lot of things to talk about, but let's start with you, Matthew Walker. Tell us a little bit about what this review article was looking at. What is happening with sleep - I mean memory and aging and its relationship to sleep? I guess that's kind of a big question, but you can give us a short answer.
WALKER: It's a fine question, we've got an hour. There's actually two articles. One was a review article that myself and Robert Stickgold wrote, and the other was a scientific publication regarding aging. So regarding the aging, it's interesting, I think all of us know as we get older that our memory starts to deteriorate and is not as precise as it used to be.
But perhaps what people don't also understand is that one of the quintessential, physiological hallmarks of getting older is that our sleep starts to deteriorate. And that deterioration actually starts to happen quite early on. We can see it in the electrical brainwaves.
And what we found in this new paper was that those two things aren't actually independent. It's not that we simply get old, and memory starts to go, and sleep starts to deteriorate. But those two things actually are significantly interrelated. And perhaps one of the contributing factors to our poor memory as we get older is the deterioration of sleep, knowing now what we know about the importance of sleep for learning and memory.
PALCA: So maybe I can turn to you, Robert Stickgold. You've done a lot of research on sleep and memory. How does that work, that you can actually tell which stage of sleep is most critical for consolidation of memories?
STICKGOLD: Well, it turns out that probably all the stages of sleep are involved, but they're involved in different ways. And so what we will classically do is we'll train subjects on some memory task, and it might be a list of words, or it might be a typing sequence. So it can be very different types of memory problems.
And we'll train some subjects in the morning and test them 12 hours later that evening, and other subjects will train in the evening and test them after a night of sleep in the morning. And we'll compare how those two groups do.
And what we see pretty consistently is that the ones who got a chance to sleep will actually be performing much better after that 12 hours than the ones who had been awake. And then what we do is we go, and we look, and we say OK, well, what about their sleep seems to predict the improvement?
So on one task it might be the amount of deep sleep you get early in the night, and this would be the case more for things like verbal memory, that you'll see that the amount of improvement subjects show after sleep will depend on how much of that slow wave, that deep sleep they get, whereas in other tasks it might correlate with the amount of REM sleep that they get.
PALCA: I see, so it's time-dependent and stage-dependent, depending - and I should say that people maybe don't know that sleep has many stages. There's REM sleep, where your eyes are flopping around and other things happen, and then there's what they call non-REM sleep, which they break down into several categories of slow-wave and fast-wave. So...
STICKGOLD: Yes, so in a given night, you go through a 90-minute cycle. You go into very deep sleep, and then your sleep lightens up, and you come into REM or rapid-eye-movement sleep, which is notorious for its intense dreaming. And then you, in the next 90 minutes, you go back down to deeper sleep and back up to REM. And you do that all night long. You get about five of those cycles in a night.
PALCA: I have to say that we are having this discussion on the 60th anniversary, not to the day, but the 60th anniversary of the paper by Eugene Aserinsky Nathaniel Kleitman describing REM sleep in Science magazine. I printed it out just so I'd have something iconic here while I was doing the show.
STICKGOLD: Yes.
PALCA: So Ken Paller, given that, is there anything in your research that shows that there's something about improving sleep that would help us with memory during the night?
PALLER: Sure, one of the dimensions that Bob almost mentioned is that there are different types of memory. So we want to be clear that these different types of memory depend on different brain mechanisms, and then in turn different aspects of sleep may be important for the different types of memory.
As Bob mentioned, slow-wave sleep is one of the most interesting types of sleep to connect to a class of memory we call declarative memory, which is recalling and recognizing facts and events that have happened to you. And so by improving slow-wave sleep, it might be possible to improve that type of memory.
PALCA: So what do you think? Is there going to be a pill someday that you can take before you go to bed or in the morning when you wake up that's going to improve not just your ability to sleep but the kind of sleep you get?
PALLER: I don't know if there'll be pills that'll have the right specificity. Right now the methods that are being used are to try to stimulate the brain during sleep, to try to see exactly what the connection is between these different stages and the memory effects that you can measure both by looking at the physiology of the brain at the time and also measuring memory after people wake up.
WALKER: And something to remember is that a type of sleep that might be good for one type of memory might not be good for another. So as you try to tweak your sleep one way or the other, you might be, you might be doing great - you might do better at remembering details of an event, but you might end up being poorer at abstracting the gist or the rules associated with it.
Those might be more useful interventions, though, in clinical populations who have deficits. So for example there's a type of neurophysiological event that we see in the EEG, what's called a sleep spindle, and patients with schizophrenia have about a 50-percent reduction in the number of those sleep spindles that they have.
So it might be that medications that can increase that would be of general value by getting them back into a normal range.
STICKGOLD: And just, too - sorry, I was just going to mention, just to deepen the plot, we also of course understand that sleep is not just only serving one particular function such as learning and memory. It serves a whole constellation of biological functions, both for the brain and also for the body. And so I think to think about how to exclusively brute-force perhaps one type of sleep because we think it's important for one type of memory, we probably do the evolutionary process a disservice thinking that it doesn't already know how to homeostatically tweak exactly what type of sleep it needs each and every night.
PALCA: Homeostatically tweaking is something I always like to take some time out to do each day.
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STICKGOLD: Yeah, I make a point myself, religiously.
PALCA: Exactly. Michael Silber, I haven't forgotten about you because - but I wanted to hold you because I think you're going to be very valuable in helping to answer some of our callers' questions. And so I'm going to go take a call now from William(ph) in Hayley, Idaho. William, welcome to SCIENCE FRIDAY. What's your question?
WILLIAM: Thanks for having me on the show. I've been diagnosed as ADHD, and I guess I've been pretty bad ADHD my whole life. But I've always - most of my whole life, even my mother reminds, even when I was a child, I, you know, four hours of sleep is about what I get at night. And it's - I wake up fully rested, and it just sleep's not a real important issue for me.
PALCA: OK, so William, let me ask Michael Silber. If William is only sleeping four hours a night, is that a problem? Would a sleep disorders clinic want to have a look at him?
SILBER: Well, there is a wide range of the duration of sleep that people seem to need. Most of us need between seven and eight hours, but there are some people who seem to need less, some people who seem to know more. My first slight concern might be whether the medications that the caller is using for ADHD, which are really stimulant medications, could conceivably reducing his ability to sleep at night.
That doesn't seem to be so because he says he's had it since he was a child, and he's not very concerned by it. In general, if short sleep is not causing any major symptoms, we're a little less concerned. The person isn't tired during the day, isn't distressed by it. But just in general terms, and I'm not referring to the specific caller's issue at the moment, there is increasing and very interesting work that short sleep, less than five hours a night, epidemiologically in a large population is associated with medical problems, including glucose intolerance, which can give rise to diabetes, high blood pressure, and on huge epidemiologic studies, on an average, a shorter life expectancy.
Now, this doesn't apply to an individual person. I want to reassure the caller that he mustn't apply this data to himself. But this is very interesting that short sleeps seems, in general, not to be good for one in a metabolic sense, apart from the fact that in general people who are voluntarily depriving themselves of sleep, and that's not what the caller's doing, who are trying to sleep less because their lives are so bus and so full, well, also have memory problems and a whole lot of cognitive impairments the next day. And we recognize that very, very well in drivers and in others who have high-stakes occupations and don't sleep enough at night.
So it's a very important question.
PALCA: OK, well, we'll take it up again after we take this short break. We're talking about sleep and memory, and so stay with us. We'll be more - we'll be back.
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PALCA: This is SCIENCE FRIDAY from NPR.
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PALCA: This is SCIENCE FRIDAY, and I'm Joe Palca. A programming note: Next week an asteroid will be passing very close to Earth, really close, I mean 17,000 miles or so, but that's close. Join Ira Flatow next week for the coverage, the live coverage of Asteroid 2012DA14 as it makes its closest approach. That's going to be live next week on SCIENCE FRIDAY.
This hour we're talking about sleep, and my guests are Matthew Walker, he's an associate professor in the Department of Psychology at University of California, Berkeley; Robert Stickgold, an associate professor of psychiatry at the Harvard Medical School; Ken Paller, professor of brain, behavior and cognition in the Department of Psychology at Northwestern University; and Michael Silber, professor of neurology and co-director of The Sleep Center - sorry, the co-director of the Center for Sleep Medicine at the Mayo Clinic in Rochester.
And I'd like to introduce one other guest who's on the line, David Dinges is director of the Unit for Experimental Psychiatry and the chief of the Division of Sleep and Chronobiology at the Perelman School of Medicine at the University of Pennsylvania. And he joins me by phone from Philadelphia. Welcome to the program.
DAVID DINGES: Good afternoon.
PALCA: So maybe I could just start by asking you, our last - just before we left for a break, we were talking with a caller who was talking about getting only four hours of sleep a night and contrasting that - he says everything's fine, he doesn't have any problems - contrasting that with people who are highly sleep-deprived.
You have worked with this problem of sleep deprivation. Tell us a little bit about how big a problem that is, both physiologically and psychologically and sleep-related - with relation to sleep.
DINGES: Well, sleep occurs in the time domain, as we all know, and many people moan about the fact that they have to spend too much time sleeping, and they'd rather be doing other things, and as a result we live in a culture where commute time and work hours and social time steal our sleep. And the question is how far can we go with that an not pay a price.
And the answer is when we start to reduce our sleep down to shorter levels, below six hours, six or less, we start to see increasing signs of dysfunction in the brain and physiologic signs in the body, regulation of food and that. So we have to be careful about reducing it.
PALLER: So we have to be careful about reducing it. The caller may be one of those naturally very short sleepers. They are quite rare, but they do occur. But it's also true that they may not be aware, and this is the big problem, they may not be aware of the deficits they're experiencing with the sleep loss. That is to say they may feel OK and be motivated, but in fact they may be at risk for falling asleep behind the wheel or not remembering things as well or in general just not functioning at their peak level because they're not getting enough sleep.
And there's a lot of people, as I understand it, who say oh, I only sleep four hours a night, and yet when they come into a lab where they can actually be carefully measured or wear a device that can whether they're moving or not, in fact they do sleep longer than that, they're just not conscious of it.
DINGES: Yes, they'll say that they can do it, and we've studied literally about 600 people through four hours a night sleep repeatedly, and most of them develop - about 75 percent will develop a significant deficit in functioning over time, even though again their full awareness of how bad it is is not very accurate as it gets chronic day after day.
But I will also tell you that there are a few people who can tolerate it. Even though they sleep seven or eight hours a night, or six and a half, they can tolerate the sleep loss better than others. So one of the mysteries right now is not only how much sleep do you need but what is your tolerance or vulnerability to the sleep loss.
Everybody will get impaired, but some people get impaired much faster than others.
PALCA: Go ahead.
WALKER: Yeah, I was just going to say...
PALCA: This is Ken Paller, right? No, no, I'm sorry this is Matthew Walker, sorry.
WALKER: That's OK.
PALCA: It's a lot of people to keep track.
WALKER: I would like to be Ken Paller, but that's - I think it's interesting and perhaps not surprising that people do suffer, the majority of people do suffer so easily when you take sleep away from them because in some ways it's never a challenge that evolution has had to face in terms of solving and placing safety nets there for because human beings are one of the few species that will deliberately deprive themselves of sleep.
So unlike the challenge, for example, for energy, our bodies actually have interesting mechanisms for storing energy in adipose tissue with fat to get us through those times when perhaps food wouldn't be abundant. Now that's not a problem we face anymore in modern-day society, but the sleep, sleep is an interesting issue in that perspective that perhaps evolution hasn't needed to face that challenge because it's not something that's common across a broad array of species.
And we human beings, we decide to engage in that type of behavior, and there doesn't seem to be good biological mechanisms immediately obvious to us that can hold onto the challenges of sleep deprivation, and hence we fall very quickly.
PALCA: OK, let's see if our callers can join the conversation, and let's go first to David(ph) in, well, North America. David, welcome to SCIENCE FRIDAY.
DAVID: Thank you, Sacramento, actually, and I must say right off the top go Bears.
PALCA: OK, yeah, well, that's nearby, yeah.
DAVID: I've often wondered how - kind of how late in the day people can really be able to sort of navigate a night of sleep and still have a coffee, you know, in the afternoon or the evening. I know people that actually, they'll have a caffeinated drink at, you know, 7, 8, 9 o'clock at night and sleep well. And what's the mechanism in our body that can handle the caffeine? For me...
DINGES: There's a biological basis for differences in responding to caffeine. Some people carry a genetic variation, just a natural genetic variation in the genes that caffeine binds to that permit them to clear it from their system rapidly, while others it takes longer to clear. And as a result, there are these differencs in how well people tolerate caffeine before they sleep at night.
But the other thing I wanted to add was aside from total sleep time, to go back to sort of timing, the key thing about sleep is timing. It's a circadian behavior. It's intended to occur at night. Nightshift work, jet lag is incredibly challenging physiologically because sleep itself is displaced and disturbed from that. So it's duration and timing and quality.
PALCA: OK, thanks for that call. Let's go now to Ken(ph), Ken in Dyersburg, Tennessee. Welcome to SCIENCE FRIDAY, you're on the air.
KEN: Does the practice of meditation affect memory and sleep?
PALCA: OK, meditation and sleep? Robert Stickgold, maybe that's something you can talk about?
STICKGOLD: I can talk about but I can't answer. We've actually tried to do this study twice. The question we were trying to ask is whether meditation can replace sleep in terms of providing a brain state that allows for that kind of offline memory processing, and for purely technical reasons, both of those experiments never quite got as far along as we had wanted.
So we don't really know. The really top-notch Nepalese-type meditators who do this as a lifestyle report that they need very little sleep. But I don't know that there have been any good studies to confirm that. So whether it can do the memory processing remains an open question, and whether it reduces the total amount of sleep you need unfortunately is still an open question, unless somebody else knows something more recent than me.
WALKER: I think the only other thing...
SILBER: Well, from a different viewpoint, patients with insomnia who have difficulty sleeping, relaxation techniques of various types have been shown in studies to help induce and support sleep so looking not specifically at meditation but relaxation, the whole range of relaxation techniques are very helpful for people with insomnia, starting from simply unwinding before sleep and then going through some very, very formal processes.
And I think in that way people can be helped when they have insomnia, but that's a little different from the question of does it affect or replace normal sleep.
PALLER: I mean this is a Holy Grail issue: Is there an activity that involves consciousness that does not involve sleep that would replace it? And in my experience, we like, Bob Stickgold and other labs, have searched for it, but we've never found anything that comes close to it. Sleep is biologically demanded by the brain and body and programmed to occur.
SILBER: I should also say, Matt Walker, that people have actually studied the patterns of brainwave activity during meditation and also placed people inside a brain scanner and actually had them meditate, surprisingly, in a brain scanner. And what you see is that the biology, as it were, of meditation, the brainwave activity patterns and the structures that turn on and off, are not the same as the stage of sleep that we at leepsauctures that turn an
So that's not to suggest that meditation couldn't have an additional benefit on memory and it couldn't perhaps affect sleep. All those things are possible. But if it did, my suspicion is that, for example, in terms of memory, it would be achieving those memory benefits in different ways based on the unique biology that is meditation versus sleep.
PALCA: So this is something - I'm glad we've kind of gotten to this because I want to know, then, if sleep is critical or at least very important for memory consolidation or long-term memory storage or call it what you will - is that the function of sleep? In other words, is that why we sleep?
STICKGOLD: You know, that's a funny question because I think we spend too much time asking. I often give the example of two tongue researchers, where one insists that the function of the tongue is to taste food, and the other insists that the function of sleep is to articulate - of the tongue is to articulate speech. And obviously the tongue is doing both of those things, and sleep is doing several things as well.
It's involved in immune functions, it's involved in endocrine regulation and it's involved in memory. And I don't know that it's right to talk about the function, although I would tend to argue that memory is the only one we've come up with that has a strong argument of why you have to become so disconnected from the rest of the world.
It turns out that the human brain is not like a VCR, you know? In a VCR you can be having the VCR record one channel while it's showing on the TV a second channel. We can't do that. If we're trying to process our memories, we can't have information coming in at the same time, or they just conflict with each other. People will do that even now as they're listening to your show.
Someone will say something and they'll start thinking about that, and to do that they have to cut off the input of the other people talking. So it's probably the memory function that requires the shutting off of conscious awareness of the outside world. But again, that's only a small part of what's happening while we're asleep.
PALCA: So David Dinges, I know you have to leave, but I want you to take a crack at that question too. I mean, is there - if you have to say to somebody why we sleep, I guess somebody said, then why are we awake? But, you know, that's a epistemological question, I think, or metaphysical. But do you have an answer for why we sleep?
DINGES: Well, I don't have the final formal, absolute answer, but I can say the problem's with the word we in that sentence. Humans like to know why they sleep as a species. The answer in this lies, why do all the animals sleep? Why is sleep so pervasive in the animal kingdom, but why are some nocturnal and diurnal? Why do some sleep in polycyclic patterns and some monocyclic?
It's highly likely sleep evolved out of the need to adapt to an environment changing in the circadian way. And as a result, it's taken on many functions, not one or two or three. Because we're a very symbolic creature that thinks symbolically and relates to the world by structuring symbolic representations of the way the world is and causal relationships, we value memory enormously.
But to the tiger, sleep exists so the tiger is faster than the antelope and can sneak up and hide and attack it and eat it. In other words, sleep serves functions for all animals: physiological, developmental functions, learning functions, attention functions. I think it's us who are obsessed with it, has to have one function, it has to be one thing, but in fact it seems to, as nature often does, ensure that it does many things.
As Dr. Walker was suggesting, it handles metabolic control. It probably protects our ability to deal with stress. It copes with immune response that's affected(ph), and a host of things. So we're probably getting enormous benefits from adequate sleep every day, and this constant war on sleep - to try to eliminate it or shorten it or find a substitute for it - is, I think, misguided.
PALCA: Well, David Dinges, I know you want to go, so I'll just say it was nice to talk to you again.
DINGES: Thank you very much.
PALCA: And David Dinges is director of the Unit for Experimental Psychiatry and chief of the Division of Sleep and Chronobiology at the Perelman School of Medicine at the University of Pennsylvania. I'm Joe Palca, and this is SCIENCE FRIDAY from NPR.
We're talking about sleep and memory and taking your calls at 1-800-989-8255. And let's take a call now from Steven(ph) in Beavercreek, Ohio. Welcome to SCIENCE FRIDAY. You're on the air.
STEVEN: Thank you. My question is about taking naps during the day.
PALCA: OK.
STEVEN: Does it have an adverse impact on the quality of sleep during the evening, especially in an older population? Thank you.
PALCA: OK. Interesting question. I'm a little unsure who to put it to. Any volunteers?
SILBER: Shall I have a go at it?
PALCA: Sure. This is Michael Silber.
SILBER: Napping is very variable, and it depends on a lot of factors. If one's sleep-deprived at night and one's really not getting enough sleep at night, taking a nap during the day may be very restorative, may not be the best way of doing it, but it is one way of doing it.
Now, we're used to the concept that our sleep should be highly consolidated at night. Our society puts a lot of store on that, that you go to bed at a regular time, sleep through. If we wake up once or twice, we feel we've got insomnia. We get up in the morning. We shouldn't nap during the day.
But not all cultures follow that. The cultures that have followed the siesta, for instance, people stay up much, much later at night, and then it's understood there will be a long nap in the early afternoon. So there are cultural changes.
There's very interesting work from, historically, from the Middle Ages, which suggests that people went to sleep close to sunset, then woke up in the middle of the night and were up and about for a couple of hours sometimes doing - interacting with neighbors, et cetera, then going back into what was called second sleep. And that was considered entirely normal at that time.
So we've got to understand that what we think is normal is in our society normal, but not the only way that the human brain and humans can deal with sleep. If you're having trouble sleeping at night, taking a nap is not generally a good thing because it can be subtracted out of the sleep at night. Generally, people have to experiment themselves.
If they're having insomnia, napping generally we try and avoid as much as possible, but it's really an individual thing, taking into account any sleep disorders one has, the amount of sleep one has at night, one's normal circadian tendency.
STICKGOLD: This is Bob Stickgold.
PALCA: Yeah. Go ahead, Bob.
STICKGOLD: I just want to add that we've done some studies looking at naps in terms of the memory processing and have been rather stunned, really, by the fact that in almost every experiment that we've tried, an hour-and-a-half nap seems to do as much good for memory processing as an entire night of sleep, and we continue to ponder that and sort of conclude that OK, we just don't get it yet. But in studies where six hours of sleep at night seems not enough to lead to consolidation of memory of a particular task, an-hour-and-a-half nap will. So there's something, at least from the memory perspective, rather magical and unusually efficient about napping as opposed to nocturnal sleep.
PALCA: Dr. Stickgold, I also think your battery might be dying on your cordless phone, if that's what you're talking to us on. So - or move closer to your bay station because...
STICKGOLD: OK, I'll get closer.
PALCA: ...you're breaking up a little bit. We have to take a short break but when we come back, we're going to talk some more about sleep, memory, learning. And I still want to challenge our - my guest to talk about REM sleep and all this, because that's another strange thing where we certainly at least seem to have a lot of mental activity going on, and I wonder if that is helpful for remembering things or not. Certainly dreams have been an important part in our psyche and our culture. Maybe they're important in our learning and memory. Anyway, we'll be back and talk about that after this short break. This is SCIENCE FRIDAY from NPR.
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PALCA: This is SCIENCE FRIDAY. I'm Joe Palca. We're talking this hour about how sleep affects how our ability to store and process memories. My guests are Matthew Walker, he's and associate professor in the department of psychology at the University of California, Berkeley; Robert Stickgold, he's at Harvard Medical School and Beth Israel Deaconess Medical Center in Boston; Ken Paller, professor of brain, behavior and cognition in the department of psychology at Northwestern University; and Michael Silber, professor of neurology and co-director of the Center for Sleep Medicine at the Mayo Clinic in Rochester. And we're interested in hearing your calls about sleep and memory, 1-800-989-8255, 1-800-989-TALK.
And I threw out this question of REM sleep and memory. Is there - I mean, earlier we were talking about different phases of sleep having different importances at different times in the night. Does anyone want to tackle the question - maybe you, Matthew Walker, about what REM is doing there in terms of this memory process?
WALKER: Yes. I think as we spoke about before, what we'll find is that REM is multifunctional in terms of the different processes that it serves. One of the things that's been emerging over the past five or six years in the literature is that REM sleep seems to serve an almost sort of overnight therapy benefit in terms of our emotional well-being and our mental health. And what's interesting is that REM sleep chemically, in terms of the anuric transmitters that swirl around the brain, REM sleep is perhaps the only time during the 24-hour period where a particular stress neurochemical called norepinephrine or noradrenaline is actually suppressed and it's completely shut down from the brain. And it seems to be that REM sleep is a perfect chemical environment, almost like a therapy session, where you can take emotional events from the prior day and perhaps just smooth the sharp edges off those experiences, and almost like an overnight soothing balm, as it were.
And there's now scientific evidence to suggest that in fact REM sleep does provide that type of dissipation, that detoxing of emotional experiences, and it's perhaps no surprise that we all have that feeling of, you know, if troubled, get to bed, you'll feel better tomorrow. So I think that that's an emerging idea and it jibes very well with the clinical literature. For example, we know in PTSD, which is perhaps one of the quintessential psychiatric conditions of dysfunctional emotional memory processing, there you see profound disruptions of sleep, including REM sleep. And by trying to ameliorate(ph) or restore that REM sleep, recent findings have demonstrated benefits in terms of clinical PTSD outcome. So I think it's a fascinating area that we still don't fully understand enough about but certainly suggests that that may be one of the functions of REM sleep, this idea of, you know, the best bridge between despair and hope is perhaps a good night of REM sleep.
PALCA: Ken Paller, do you want to take a crack at that? is that your sense of REM as well?
PALLER: Yeah. Sure. And I can make a connection between that and the memory story. So the idea that Matt was talking about that we're doing some emotional regulation, perhaps, the current concerns of the day that the emotional things that are bothering us are something we work on through the night and there's evidence that the different REM periods are involving a progression of that is we think about the recent events and relate them to all the memories that are related to the same idea and might help us solve the problem. So these higher principles of thinking about current problems might be what are recruiting both the processing during REM and perhaps some of the memory processing that happens in other stages of sleep as well.
PALCA: Let's take another call now - Oh, sorry, go ahead. who's that?
STICKGOLD: Bob Stickgold.
PALCA: Oh, hi, Bob. Yeah. Go ahead.
STICKGOLD: I was just going to comment that there's also evidence that suggest that deeper sleep, that what we call slow-wave sleep, non-REM sleep, might be more involved in sort of strengthening memories in a way that they're for REM. So for example, if you want to remember someone's name or phone number that might be where that non-REM sleep is valuable. And that REM sleep seems to be more involved in memory processing where you're not trying to exactly remember it in the form that you first saw it but rather to extract meaning from it. So to get patterns or to figure out the rules of something or to extract just to get the sort of the executive summary. But that seems to be more of what REM sleep that's about and that would fit in with the emotional piece too because, of course, if something had happens during the day, you don't simply want to remember it better than next morning. You want to understand it.
You want to relate it to other things in your life and see how it fits into your associative networks and, sort of, process it that way. And that seems to also be part of what REM is doing.
PALCA: OK. Bob Stickgold, thank you for that. Let's go to a caller now and take a call from Collin in Ridgeville, Indiana. Collin, welcome to SCIENCE FRIDAY. You're on the program.
COLLIN: Thank you. My question is regarding a - not the lack of sleep, but too much sleep. The lack of sleep has been well-studied and researched, it seems like. However, I'm very well aware of the physical effects of commonly known Sleeping Beauty syndrome, but I'm wondering what the psychological effects can be and if that's even been studied. Unfortunately, I have not been able to find any material on that.
PALCA: Anyone? Matt Walker? Matthew Walker?
WALKER: Maybe (unintelligible)
PALCA: Hypersomnia or...
WALKER: Yes. So hypersomnia has been something that's been discussed in the literature, in depression, for example, this idea of sleeping too long. What's interesting is that the recent evidence that has tried to, sort of, place a scalpel and separate out, is it really sleeping too long, or is it staying in bed too long?
And when you do those types of more careful approaches and analysis, I think there remains some controversy, at least in the depression field, as to whether it's really simply too much sleep, hence hypersomnia; or in fact, it's just too much time in bed yet with a perhaps normative amount of sleep. So that's in the depression literature, but perhaps I'll leave it to some of the other clinical folks to discuss the more general issue of hypersomnia.
PALCA: Michael Silber, do you see a lot of hypersomnia patients in your clinic?
SILBER: Well, we see lots of hypersomnia in the sense of people who cannot keep awake during the day. And usually, there's a clear answer to that: either insufficient sleep at night, medications, or drugs or diseases such as obstructive sleep apnea or narcolepsy. Long sleepers are very interesting. You remember, I was talking a little earlier about the ill effects of too little sleep.
Actually, multiple studies have shown, epidemiologically, that it's a u-shaped curve, and that sleep that is too long, beyond nine or 10 hours, also seems to have - be related to reduced mortality. And whereas we understand a great deal about the short sleep, we understand very little about the effect of too much sleep.
PALCA: So I'm sorry. Did you just say that too much sleep reduces your mortality?
SILBER: Increases mortality, I'm sorry. It's the u-shaped...
PALCA: Oh, OK. I just want to make sure I had the right - you going in the right direction.
SILBER: Yes, thank you for correcting that. But too little and too much seems to be associated with increased mortality. Now whether that is simply that people with too much sleep have a whole lot of chronic illnesses, fatiguing illnesses - and it's the illness that does it rather than the sleep, is completely uncertain at present, a lot less certainty about this. But there are some people who just have long sleep, just as there are people who have short sleep. And if they get 10 hours sleep at night or 11 hours, they feel fine the next day.
If they get less, they feel sleepy. And we call them long sleepers, but we don't understand them very well at all. Presumably, it's a genetic variability. But people who really sleep too much at night probably - and still feel tired during the day probably have a disorder. And there's a spectrum of disorders, including something called idiopathic hypersomnia, that are not well understood yet.
PALCA: Right. Collin, you mentioned Sleeping Beauty, and I guess the answer here has more to do with Goldilocks, where you don't want too little - you don't want your porridge too hot or too cold. You want it just right. So that seems to be the answer there. Thanks very much for that call. Let's take another call now and go to Adam in Fresno, California. Adam, welcome to SCIENCE FRIDAY. You're on the air.
ADAM: Great. Thank you for taking my call. I had a question about polyphasic sleep. And...
PALCA: OK. Now you have to define that. Somebody else mentioned that, and I'm remiss for not explaining what polyphasic sleep is. How would you define that?
ADAM: I guess, from my limited understanding, is structured napping.
PALCA: OK. Is that - hold on just a second. Now, can we all agree that that's an appropriate use of the term?
STICKGOLD: Polyphasic just means that you sleep more than one time during 24 hours.
PALCA: OK. Bob Stickgold, thank you for - so go ahead, Adam. I didn't mean to interrupt, but I just wanted to make sure we were all talking about the same thing.
ADAM: Sure. And if there is any research on increasing productivity during the day or of it actually decreases cognitive ability by either - some of the examples I saw were four 30-minutes naps every six hours or six 20-minute naps every four hours. And if you just have any experience or...
PALCA: Oops, sorry. Did I cut you off there?
ADAM: Oh, no.
PALCA: I'm sorry I did that. Go ahead. You were saying, if there are any evidence for what, I'm sorry?
ADAM: If there's any evidence for an increase in productivity by switching to kind of a more polyphasic sleep schedule.
PALCA: OK. Any takers on that one?
STICKGOLD: So there's this new fad, if I may call it that, that I've noticed amongst college students, which is this concept of trying to spread your sleep out over many, many short - many more, but shorter bouts of sleep in the day. And I don't think there's any evidence that that's particularly helpful. When I hear students talk about it, they're trying to actually come up with a method of reducing their total sleep time. And I think David Dinges, who is gone now, has actually done a study showing that you can't - if you take a nap during the day, it doesn't mean you need less total sleep in 24 hours.
There are some benefits from naps, just in terms of sort of, I don't know, I often describe it as emptying your inbox and sort of getting you back up if you're feeling burnt out. But whether that's because you weren't getting enough sleep the night before or some real special benefit of napping, I don't think that studies have been done that can answer that.
WALKER: I think also - sorry. Matt Walker...
PALCA: Go ahead. Sure, man.
WALKER: ...to speak about that. If you look at how humans tend to want to sleep, it seems to be either, you know, sort of a monophasic way or at least a biphasic way, where there's, perhaps, a long bout during the night and then maybe a siesta-like pattern during the day.
But certainly, what we don't adopt is as adults is this highly polyphasic sleep cycle and naturally is what I mean. And I think if it had such extraordinary benefits to be sleeping at a polyphasic way, evolution would have naturally sailed off, sort of directional development along that pathway. The fact that we don't have that biologic pressure to have highly polyphasic sleep, I think, probably tells us something in terms of, truly, whether it's useful or not.
PALCA: We're talking about sleep, sleeping and memory, and how those two things are related. I'm Joe Palca and this is TALK OF THE NATION: SCIENCE FRIDAY. And let's take one more call now and go to Bryan(ph), Bryan in Brighton, Michigan, I guess. Welcome to SCIENCE FRIDAY. You're on the program.
BRYAN: Thank you for taking my call.
PALCA: Sure.
BRYAN: I have a lot of questions and I don't want to get too in-depth with it. But I had insomnia, and then later on, developed PTSD from being overseas. And I've always had a problem with sleep. I've done sleep studies. On overage, I will get, literally, one to two hours of sleep a night until about the fourth or fifth. And then, I'll start getting double vision, tremors, slight-like sound hallucinations. And I've done everything under the sun for medication-wise. And also, I've gotten, you know, a lot of friends - I was in sleeping there. They've taken the TV out of my bedroom. And the only thing I associate with my bed is sleep. I guess, my question is, is there any thing out there that, you know, I might be missing that could help me get sleep. I have trouble, actually, going to sleep. I just can't get to sleep.
PALCA: OK. Bryan, you understand that we can't give you any specific medical advice, but maybe Michael Silber can talk about what's in the pipeline or what new things are becoming available.
SILBER: Sure. Insomnia is a symptom, not a disorder. So when first - when dealing in general terms with a situation of severe insomnia, one wants to ask, what are the causes, what are the contributing factors. You mentioned that, unfortunately, you have had experiences which resulted in PTSD, which is, certainly, going to be a contributing factor, but also that your sleep was bad for as long as you can remember. So one would want to, in general terms, look at anything that disturbs sleep: how much depression they might be, anxiety in a person, any physical factors affecting sleep, such as the condition of restless legs, pain. There are many things inside the body, outside the body that can affect sleep.
So the first approach we would generally take is to try to work out what are the contributing factors to this problem of insomnia? Then, once - if we've corrected those factors or none of them are particularly correctible, we would then have generally two approaches. The one you've tried clearly, which is sleeping tablets, hypnotics, many of them work, but they don't work perfectly. And sometimes, the expectations may be a little more than we can achieve with them. There are new sleeping tablets being developed. We're going to have new mechanisms of sleeping tablets available. And with time, hopefully, we'll get sleeping tablets that have better effect with fewer side effects.
The other and generally more helpful approach you've alluded to, and that's what we call cognitive behavioral therapy, which is a series of well-proven techniques, well-studied, shown to work in controlled trial to correct problems of insomnia by behavioral approaches. And you've mentioned some of the things that you've learned to do. Now, obviously, I don't know to what extend you've really - I've gone through a formal program with a behavioral psychologist who is trained in sleep psychology. But if you haven't had a really formal program, that might be another approach that people with severe insomnia can do. Self-help works up to a point, but sometimes, one needs the help of - ongoing help with a specialized psychologist. We don't have a perfect solution to insomnia. And I'm really feel so bad about people with severe, intractable insomnia. But generally, with combinations of things, we can provide some help.
PALCA: OK. Well, thanks very much for that. Ken Paller, I'm going to give you the last word. And I - we don't have a lot of time, but I just wonder if you could quickly tell me, where do you see the field of sleep research going? Is this going to be - is sleep and memory going to be the focus? Or do you see something else coming along that's very important?
PALLER: Well, I'd like to take the view that's contrary to some of the views we've heard earlier, that maybe sleep isn't optimized already by whatever factors have led to where we are now. And that there are possibilities for, maybe, improving things, improving memory processing during sleep, for example, is one thing. And so I think together with the clinical methods Michael has mentioned, there are possibilities for making sleep better and in the course of doing that, improving the various benefits of sleep on arousal and, perhaps, on memory as well.
PALCA: All right. Well, I'm afraid we have to leave it there. It's been a fascinating hour. Thank you all for joining me. Matthew Walker is an associate professor in the department of psychology and principal investigator of the Sleep and Neuroimaging Lab at the University of California, Berkeley. Robert Stickgold is an associate professor of psychiatry and director of the Center for Sleep and Cognition at Harvard Medical School and at Beth Israel Deaconess Medical Center in Boston, Massachusetts. Ken Paller is a professor of brain behavior and cognition in the department of psychology at Northwestern University in Evanston, Illinois. Michael Silber is professor of neurology and co-director of The Center for Sleep Medicine at the Mayor Clinic in Rochester, Minnesota. So, gentlemen, all, thank you for joining us.
I know there are times when I wish I had that for my children.
STICKGOLD: Joe, get a good night sleep.
(LAUGHTER)
PALCA: OK. I'll do that. Thank you.
WALKER: You sleep well.
PALCA: I'll work on it, believe me.
In Washington, D.C., I'm Joe Palca.
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Researchers Point To The Demise of the Dinosaurs
The idea that a comet or asteroid impact led to the downfall of the dinosaurs has been around for years. Now, Paul Renne and colleagues report in Science that they've narrowed down the timing of that collision. It's practically simultaneous with dinosaur extinction.
Copyright © 2013 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.JOE PALCA, HOST:
This is SCIENCE FRIDAY. I'm Joe Palca.
You know the theory that a big collision, a comet or an asteroid, something like that, helped kill off the dinosaurs? The idea has been around for a while. But this week, new research published in journal Science provides more accurate dates for the giant impact and the dino demise.
And, oh, by the way, if you're thinking about this, it's not going to be a problem. But next week, Ira is going to be talking about another asteroid. This is the 2012 DA14 that's making a close approach to Earth. So you don't have to worry. It's not going to kill us all off, but you want to listen next so you'll hear Ira and learn how we found this comet.
But there was another one that did hit Earth 66 million years ago, and the results show - so the question has been, did that - or how did that affect the dinosaurs' disappearing? And now there's a paper in Science that shows that these events, the asteroid or a comet hitting the Earth and the demise of the dinosaurs, were within 32,000 years of each other, which is just a blink of an eye when you're looking back at events 66 millions years ago.
Joining me now to talk about it is Paul Renne. He's a professor in the Department of Earth and Planetary Science at UC Berkeley and director of the Berkeley Geochronology Center. Welcome to the program.
PAUL RENNE: Thank you, Joe.
PALCA: So I want to be clear here. Are you saying - I mean, does this paper say now we know what killed off the dinosaurs?
RENNE: Well, yes and no.
(LAUGHTER)
PALCA: No, no, no. No fair. This isn't a congressional hearing. You have to...
RENNE: It's a really nuanced issue. And the question is, was there a single cause or were there a pattern of events that collectively did the job? And what our results show - and this, of course, is really just building on a theory that's existed for more than 30 years now. What our results strongly support is the idea that the impact of a large body, whose crater is found in the Yucatan Peninsula of Mexico, that that impact coincided to a very, very close proximity in time with the extinction. There were no dinosaurs that survived after that impact occurred. And many, many other creatures that are less photogenic and famous than dinosaurs went out as well. And so clearly, in our view, that was the final straw.
But there is evidence - and this has been overlooked by many people who have been interpreted our paper in various ways, surprisingly - that a lot of stressful conditions were occurring on Earth for something like a million or perhaps even two million years before this impact occurred. There is evidence that there were very rapid and very severe climate swings, temperature changes of up to, say, eight degrees centigrade over a very, very brief time intervals. That's a big change, changes in sea level and extinctions of dinosaurs and other animals, most notably on land, so mammals and dinosaurs both.
So these things were going on. And the extent to which these reflected global conditions or maybe only reflect local conditions in the areas where the fossil record is most complete, that's debated. But we think that there is sufficient evidence that climate deterioration or climate change was underway and that this really was just the final tipping point, if you like.
PALCA: If you have a question that you want to ask Paul Renne about this contemporaneous event 66 million years ago, give us a call. Our number is 800-989-8255, 1-800-989-TALK. So what is the need to refine this? Is there really - I mean is there still such a big debate about the relationship between the Chicxulub crater that this asteroid or comet caused and the dinosaur demise? I mean, what drew you to this topic?
RENNE: Well, I came at this topic for fairly esoteric reasons that have to do with calibrating our ability to date things in the geologic record.
And in so doing, I began to appreciate that - the existing data for this particular event, which is a nice sort of benchmark in the geologic record. We're inadequate really. And, in fact, the existing data, up until now, actually indicate that the impact and the extinctions were not synchronous. They're distinct within analytical uncertainties. They would appear to be separated by about 180,000 years. That is the extinctions appear, based on the existing radioisotope data, to have occurred 180,000 years before the impact.
Then on the other hand, there is a fairly small minority, I think, but still a fairly vocal one, of scientists that believe that the impact occurred 300,000 years before the extinctions. So with that level of discord in the community, it seemed appropriate to try and do a better job of dating both of these events, both the impact and the extinction and really lay those questions to rest.
PALCA: But to be clear, your data shows - which one does your data show came first?
RENNE: Well, I mean, the numbers are indistinguishable. So I would put absolutely no credence on our ability to tell which happened first. But let me see - and because they're so synchronous, I don't even really think of it that way.
PALCA: I see.
(LAUGHTER)
RENNE: I have to retrieve some distant memory cells here.
PALCA: That's OK. I didn't mean to put you on the spot. The point being here, that you're saying it's impossible, with available technology, to say whether it was before or after, and certainly not in so many hundreds of thousands of years.
RENNE: Right. We just can't tell them apart.
PALCA: All right. Well, let's see what our callers have to say about all this. And if I've done it properly, let's go to Daniel in Morristown, New Jersey. Daniel, are you snowed in yet?
DANIEL: Almost.
PALCA: OK. Well, I'm glad your phone is still working. What's your question?
DANIEL: Yeah. Well, I know - I was recently reading about the extinction of the mammoth species and that several, you know, subspecies survived far longer than we previously thought - you know, many tens of thousands of years longer in isolated regions. And I was wondering if there's - the same thing occurred with - during the dinosaur extinction, if there were any regions or isolated species that managed to survive longer, or vastly longer, than the general population of dinosaurs.
RENNE: Hi, Daniel. That's a really good question. And it sort of depends on how closely you look at the problem. Just to start off my answer, though, I would say that there is no credible evidence for any dinosaurs having survived past the level at which we can say, OK, here's where the record of the impact occurred. So it's a little layer of sediment that occurs all around the world, in the oceans and in many stratigraphic sequences on land, particularly in Montana where we've done our work. So you can really - you can put your finger on this layer, and that layer is characterized by high concentration of iridium and things like shocked quartz and other features that are really symptomatic of an impact. And nobody has ever found a dinosaur that was clearly alive after that time or above that level.
There have been some claims of dinosaur bones having been found above this level. And in every case that I'm aware of, those bones were what we would call reworked from lower levels. So they've been eroded from somewhere else and transported by streams and such, and end up appearing to be above the layer and hence, younger. But in all cases I'm aware of, you can show pretty easily that that's what happened.
But, you know, it's a really intriguing question. Did - how synchronous was the extinction of dinosaurs? Can we ever hope - and we certainly can't do this right now - but can we ever hope to be able to pin it down to a matter of, say, months? And this would - this would be a huge breakthrough because the ability of various animals at different trophic levels to find refuge or to survive certain types of effects is quite amazing. And it would be surprising to me if in one afternoon, an entire group of animals was wiped out. But we don't really have the clarity of tools to be able to answer that question.
PALCA: Daniel, thanks very much for that question.
DANIEL: Thank you. It was very interesting.
PALCA: OK. You know, that actually makes me wonder, though, Paul Renne, can you imagine those tools becoming available? Because, you know, it seems to me, 30 years ago, people would've said, we'll never be able to see a planet going around a distant star. That's way too far off. And now they can do that or they can infer their existence anyway. So what do you think?
RENNE: Yeah. No. And we always have this tendency to think that, you know, technology is not going to advance much beyond where we are today. I'm an optimist. I'd like to think that we could do that at some point. I think that it will require methods that are fundamentally different than what we have available today. In other words, it won't be using the same kinds of equipment that we have been using but just slightly better and more improved versions of those. It's going to require something completely different. And I can't conceive of what it's going to be. If I could, I'd be...
(LAUGHTER)
PALCA: Yes, I know exactly. It's like predicting the stock market. If you did that, you wouldn't be talking to me.
RENNE: Oh, sure, I would.
PALCA: Well, thank you very much for that. Let's take another call now and go to Barney, Barney in Kenner, Louisiana. Welcome to SCIENCE FRIDAY. You're on the air.
BARNEY: OK, thanks. I have a simple question. It's sort of like the last one. I'm just curious how come some creatures did survive, like turtles and alligators and things like that, and the dinosaurs got wipe out. But those creatures seemed to manage and they're still around today?
RENNE: Hi, Barney. That's a good question. I'm going to have to start off by pleading the fact that I am not paleontologist, and the specific resistance that different types of animals have to various environmental stresses is not really something I'm an expert in. I'm a geologist. And from what I understand from my colleagues who more knowledgeable than I, there was a huge variation in sort of survivability. And as - obviously know something about this. It seems to have something to do with - as far as I know, with which animals were adapted to living in relatively wet environments. So turtles and other aquatic vertebrates seemed to do better. And why that it is, I really - I don't know. I have to just tell you honestly.
PALCA: OK. Barney, you stumped our guest. Thank you for doing that. Appreciate it. We're talking with Paul Renne about the dating of the extinction of the dinosaurs. I'm Joe Palca and this is SCIENCE FRIDAY from NPR.
So the tools that you do have, have - you've now gotten this, I think, I read 32,000 years plus or minus. I mean, first of all, can you - you can't really squeeze anything more out of that. But are there are other timing issues that your techniques could be applied to that would be useful to know the answers for?
RENNE: Oh, sure. Yeah. The - and actually, just to go back, we can actually squeeze more out of this particular scenario. And it would be useful to that, I think, at some point. It takes incrementally more and more work, more time, more analysis to do a little bit better. So at this point, we don't really have a lot of pressure to push the precision too much on this topic, but we could, if we really wanted to. So there are other extinctions in the geologic record and, for example, at the end of the Paleozoic Era, the so-called Permo-Triassic boundary, which was actually the largest, most profound extinction that we know of in the history of life. That happened about 252 million years ago.
And it is associated with a very large - what we call flood basalt problems, of huge outpouring of magma that happened in Siberia, at, as far as we know, exactly the time, same time. So when I say as far as we know, what do I mean by that? Well, right now, you know, we're talking about a level of synchrony that set about the 100,000-year or maybe 50,000-year level. And it would be nice to be able to refine that a little bit. So one of the things you want to know is if, in fact, volcanism - and we think this is a factor at the end Cretaceous as well. We think volcanism is very likely to have been a factor in the earlier pre-impact environmental stresses.
So it would be nice to how long it takes for volcanism to generate gases that modify climate that actually start to have effects on the environment. And that's - those are the kinds of questions that we could be in a better position to address, if we can date things more precisely.
PALCA: Is there anyway from your data, to tell when the climate in this particular event began to stabilize or is that something that's different data set all together?
RENNE: No. Our exact, same type of data can address that, and that's really where we're headed now. We would hope to start to be able to sequence events that are manifesting in the deep ocean records, for example, with what we see on land. And there are some indirect ways bring those two records together on a uniform timescale. It requires calibrating when magnetic reversals occurred and calibrating the record of climate changes that are forced by Earth's orbital rhythms. And if we can bring all those things together and get them to be reading the same scale, we do have the possibility of really understanding these climate changes and their possible driving forces in much more detail.
PALCA: That's great. Well, we'll look forward to the next set of results and thank you very much for joining us today, Paul Renne.
RENNE: It's been my pleasure, Joe.
PALCA: Paul Renne is a professor in the Department of Earth and Planetary Science at UC Berkeley and director of the Berkeley Geochronology Center.
Copyright © 2013 NPR. All rights reserved. No quotes from the materials contained herein may be used in any media without attribution to NPR. This transcript is provided for personal, noncommercial use only, pursuant to our Terms of Use. Any other use requires NPR's prior permission. Visit our permissions page for further information.NPR transcripts are created on a rush deadline by a contractor for NPR, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of NPR's programming is the audio.View the original article here
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