Science Magazine Podcast

Science Magazine Podcast Transcript, 3 February 2012 http://podcasts.aaas.org/science_podcast/SciencePodcast_120203.mp3

Music Host – Kerry Klein Welcome to the Science Podcast for February 3rd, 2012. I’m Kerry Klein. Host – Sarah Crespi And I’m Sarah Crespi. This week: corals and climate change [00:48], the complex relationship between brain structure and drug addiction [08:56], and a rundown of the winners of the 2011 Visualization Challenge [16:50]; plus, a few stories from our online daily news site [27:19]. Promo Support for the Science Podcast is provided by AAAS: the American Association for the Advancement of Science. Advancing Science, Engineering, and Innovation throughout the World for the Benefit of All People. AAAS—the Science Society—at www.aaas.org. Music ends [00:48] Host – Kerry Klein As carbon dioxide builds up in the atmosphere, it also builds up in the oceans, which can result in a rise in sea surface temperature and ocean acidification. In theory, these processes are bad news for temperature- and pH-sensitive organisms, like corals and others with calcareous skeletons, but a paper published this week on the growth rates of coral reefs during the industrial era uncovered some surprising results. Timothy Cooper of the Australian Institute of Marine Science spoke with me about what this research forecasts for coral reefs. Interviewee - Timothy Cooper Our study looked at the rates at which corals are laying down their skeletons for the past century and compared them to observed water temperatures on a range of coral reefs spanning 11 degrees of latitude in the southeast Indian Ocean off of western Australia. Probably the most important result was that we found no widespread decline in calcification rates in recent decades for these corals on these coral reefs, which is good news. But we found evidence that the responsiveness of coral calcification rates to changes in water temperature had been more pronounced for coral reefs in our more southern cooler waters in western Australia. So in actual fact, at these coral reefs, there was an increase in calcification rate that matched the warming at these higher latitudes, which is a contrasting result with coral reefs from the Great Barrier Reefs on the east coast of Australia.

Interviewer - Kerry Klein Okay. So essentially we already know that the excess carbon dioxide in the atmosphere is resulting in increased sea surface temperatures in some places and also in variable ocean acidification. And so your goal with this study was primarily to see what effects these processes have on corals. Is that right? Interviewee - Timothy Cooper That’s correct, yeah. We started this project addressing that question – looking at possible drivers of climate change factors, such as increased sea surface temperatures and ocean acidification on coral growth rates in western Australia. There have been some recent studies published from the Red Sea, Thailand, and also the Great Barrier Reef that were reporting recent declines in coral calcification rates. And we wanted to look at corals growing in western Australia to see whether there were similar sorts of declines over recent decades and compare that to observed measurements for sea surface temperatures. Interviewer - Kerry Klein Now what I find particularly interesting is the process by which we measure the growth rates of corals. So can you explain how you were able to actually quantify these calcification rates over the last century? Interviewee - Timothy Cooper First of all, you have to start off by diving with a hydraulic coral coring system. So it involves a team of divers in the water to essentially take a biopsy of the coral skeleton. And with that coral core, we can then reconstruct the growth rate through time of the massive corals themselves because these particular types of corals, Porites, they actually grow in annual growth bands. So they continuously lay down a skeleton over the top of previous skeletal deposits. So by knowing the time of collection of the core, you can just count back and establish a growth chronology for the coral—it’s a bit like aging trees using growth rings in a tree. And we can then use a densitometer to measure the calcification rate in each of those bands. So we then compare that annual growth rate to the sea surface temperature for that particular year and then analyze the relationship between the two statistically. Interviewer - Kerry Klein Now you’ve already mentioned that the results that you found here surprised you and didn’t quite correlate with the growth rates published for corals in other parts of the world. So can you just talk a little bit more about the results that you found when comparing your measured coral growth rates with the historical sea surface temperature data? Interviewee - Timothy Cooper Certainly. It was very surprising, and I think this was the key interesting factor from this study. Certainly we were expecting in recent times that there would be a decline in coral growth rates for these particular corals. And in actual fact at our northernmost sites – so the sites up near the Rowley Shoals at the top end of our study area – there was only a

very small increase in calcification rates, which matched a much smaller increase in decadal sea surface temperatures over our study period. But the most pronounced increase was at our most southerly sites where the water is a little bit cooler, and the change in sea surface temperatures had been greater. Interviewer - Kerry Klein So why do you think that the corals in western Australia appear to be growing at different rates than other corals around the world and even those in other parts of Australia? Interviewee - Timothy Cooper What is causing that, and why is that different to the Great Barrier Reef is a very good question. There could be some link to differences in oceanography between the east and west coast. So on the west coast of Australia, we don’t have the labyrinth of reefs that they have on the east coast, which form the Great Barrier Reefs. There’s also less people – there’s a smaller population on the west coast, particularly in the northern part of our state. So there could also be some less runoff and water quality factors that come into play. But it’s still a question that we need to dig into a bit deeper to fully understand why our corals aren’t declining in their growth rates like they are on the east coast. Interviewer - Kerry Klein And where does ocean acidification come into play here? Did you also measure that over the same time period? Interviewee - Timothy Cooper Unfortunately, there’s not the same sort of observational data set for ocean acidification or ocean chemistry that we have for sea surface temperatures. Certainly ocean acidification is happening – there’s observational data from Hawaii and Bermuda that is showing that the open oceans are changing in their ocean chemistry, which is consistent with the extra carbon dioxide that we’re putting into the atmosphere. But our study shows that today it’s changes in temperature that are having a dominant impact on coral growth. But this doesn’t preclude ocean acidification becoming an additional factor in the near future. Exactly when we’re not sure but we know that there’s an additive effect when you look at temperature and changes in ocean chemistry on coral growth rates. Interviewer - Kerry Klein So, for now this almost sounds like a good thing – that as sea surface temperature is rising that these corals appear to actually be having sort of a growth spurt, if you will. Is this the full story here? Is this really all good news? Interviewee - Timothy Cooper It is good news up to a point. Corals grow or increase their growth rates up to a thermal optimum that they have for their calcification rates. So, yes, it is potentially a good news story, but the flip side is that what we are seeing is that these corals are sensitive and vulnerable to small changes in water temperatures. So, even though we’re not finding declines in coral growth rates, which would potentially be quite a bad story, we are

seeing that they are responding to changes in their environment. So I think we do have to treat this a little bit cautiously and just be aware of what the corals are actually telling us. Interviewer - Kerry Klein Right. And given all of that, how would you quantify the immediacy in our need to protect corals? Are there any sort of steps that we can or should be taking right now? Interviewee - Timothy Cooper In terms of preserving and conserving coral reefs, what our study has shown is that there are responses that we can measure to short-term changes in temperature. But in the longer term, as we’ve just been talking about, these responses will be compounded by progressive impacts of ocean acidification. So what we’re in now is an era of rapid environmental change for the world’s coral reefs, and this study provides evidence that coral reefs are sensitive to these changes. So I think that the key immediate step is halting and reversing the rapid environmental changes, which is going to be fundamental to provide coral reefs, as we know them today, with a future, particularly for our grandchildren and their grandchildren. Interviewer - Kerry Klein Well, hopefully we can. Timothy Cooper, thank you so much. Interviewee - Timothy Cooper Thanks, Kerry, and thanks for having me on your show. Host – Kerry Klein Timothy Cooper and colleagues discuss the relationship between sea surface temperature and coral growth in a Report this week. Music [08:56] Host – Sarah Crespi Human behavior is thought to be the result of an ever-shifting balance between activating and inhibitory signals in the brain. But what happens when the balance is tilted in one direction: toward impulse? I spoke with author Karen Ersche about her study of the relationship between brain structure, self-control, and drug addiction. Interviewee - Karen Ersche Stimulant drugs, such as cocaine, are highly addictive, but not everybody who uses cocaine becomes dependent on it. And further, data suggests that less than 20% of people who try cocaine will become dependent on it within 10 years of their first use, but the likelihood of dependence is increased in people who have a family history of drug and alcohol dependence. So in other words, there seems to be a genetic risk of addiction, but we currently know very little about how this risk is inherited. So the questions that we wanted to find out in this MRC funded study were, “Why is it that some people get

hooked on cocaine and others don’t? And why is it so difficult for those people who get hooked on cocaine or get dependent on cocaine to stop using it for good?” Interviewer - Sarah Crespi Well, let’s get into the details of this paper a little bit. Addiction is thought to be a heritable trait, as you mentioned, but how such a complex attribute could be inherited is is not well understood. Can you tell us how you set up this study to look at this? Interviewee - Karen Ersche In the present studies, we used a so-called endophenotype strategy to identify vulnerability markers for the development of stimulant dependence. And the brain would be the most obvious place to look for vulnerability markers because drug dependence is increasingly recognized as a relapsing brain disorder. And there’s a wealth of evidence showing that the brains of people who have been using drugs, such as cocaine, have a different structure. However, we don’t know whether this different brain structure has predated drug taking, rendering these individuals vulnerable for the development of dependence, or whether these brain abnormalities are effects of their long-term cocaine use. So what we’ve done is we compared the brains of people who have been using cocaine for a long time – that have been dependent stimulant drugs – with those of their full brothers and sisters who have no personal history of drug dependence and with the brains of non-drug using, unrelated, healthy volunteers in the community. The abnormalities that are common in both of these sibling pairs would suggest that there’s a predisposing cause rather than a long-term effect of drug use. And, while in addition to comparing brain structure, we also looked at behavioral measures of self-control. Interviewer - Sarah Crespi What kinds of behavior did you look at? Interviewee - Karen Ersche We found that not only the drug-dependent individuals but also their non-dependent siblings showed significant impairments in self-control. But this did not come as a surprise to us. So people who are addicted to drugs have problems with self-control. And loss of control over drug use is a diagnostic criterion for drug dependence. And poor self-control has frequently been reported in people at risk for dependence. So for example, adolescents with poor self-control abilities are more likely than their peers to experiment with drugs. So the siblings in our study, they showed these poor self-control abilities and really showed that they had clear signs of vulnerability. Interviewer - Sarah Crespi How did you test self-control in a laboratory setting? Interviewee - Karen Ersche Basically we used the stop-signal test, which is widely and most common measures of inhibitory control. So participants see a stimulus, and they are told to respond to a stimulus. So it’s very easy, and you get very in the swing of doing that. And they suddenly get told to stop, and some people are very good at stopping, and others are bad

at stopping, in particular, when you have to stop with short notice. And the time it takes or the time they need to stop suddenly gives an indicator of their self-control. Interviewer - Sarah Crespi So how do these behaviors that you’re observing in the lab relate to differences in brain structure? Interviewee - Karen Ersche Well the ability to regulate behavior is subserved by the prefrontal part of the cortex. And we found that white matter tracts that connects the frontal part of the brain with each other and also with the rest of the brain were poorly connected in both the drugdependent individuals and their siblings. In other words, their brains were less efficiently wired than the brains of unrelated healthy control participants. And we could show that these inefficient connections were directly related to their poor performance on this selfcontrol test. And this is particularly important with regard to addiction because drugs that are abused are highly reinforcing. So people with a diminished ability to recruit prefrontal networks for regulating their behavior are particularly susceptible to the effects of addictive drugs, such as cocaine. What I probably also should say is that in drugdependent individuals the changes in the brain were exacerbated, and we could also show that these were directly related to the duration of their cocaine abuse. So in other words, taking drugs – drugs like cocaine – seems to aggravate the damage. Interviewer - Sarah Crespi So you saw similar structures, similarities in the structures, of the brain of the siblings and the drug-addicted individuals that were much different than your healthy volunteers but that it was exaggerated by drug use. Interviewee - Karen Ersche Yes. Poor self-control abilities are not the only marker that renders people vulnerable for addiction. And the propensity to form habits may also increase their risk for developing dependence. And it has been suggested that some forms of drug addiction are developed through bad habits that get out of control. And what we found in this study was that both the drug-dependent individuals and their non-dependent siblings showed significant enlargements of the putamen. And the putamen is a brain structure that is critically involved in the formation of habit. But this in itself is not necessarily a problem because there are some people who are just creatures of habit. So it means that they easily adopt rituals, they easily get into habits. And in fact, the propensity for forming habits may easily be an advantage provided the habit is a good one. However, these people also form bad habits very quickly. And when bad habits are paired with poor self-control abilities, this may be particularly difficult then to kick the habit. And this is exactly what we see in people who are at risk of drug dependence because they start taking drugs at an early age; they quickly develop drug-taking habits until their drug use gets out of control. And when these people then make a decision to get off drugs, they really struggle to beat their addiction. Interviewer - Sarah Crespi

So you observed this link between siblings, brain structure, and addictive behaviors. What are the next steps? What can we take away from this in terms of tackling the problem of drug addiction? Interviewee - Karen Ersche The siblings have the same vulnerability as their drug-dependent brothers and sisters. And the siblings’ mean age was around 33 years, so this suggests that they may have had lots of opportunities to initiate drug abuse and to develop dependence, but they didn’t. So I think for us the next step would be to explore how these siblings – who don’t take drugs – manage to overcome their brain abnormality in daily life. So it is possible that the siblings benefited from something, some form of resilience, which may have counteracted their familiar vulnerability. A better understanding of siblings’ resilience would be extremely useful for the development of strategies to prevent people from becoming addicted to drugs, people who are particularly at risk; and a better understanding how the siblings compensate for their brain abnormalities may provide guidance for the rehabilitation of drug-dependent individuals. Interviewer - Sarah Crespi Karen Ersche, thank you so much for joining us today. Interviewee - Karen Ersche Thank you. Host – Sarah Crespi Karen Ersche is the author of a report on brain structure and drug addiction in this week’s Science. Music [16:50] Host – Sarah Crespi Picture in your mind an atom. Does it look like plum pudding, the solar system, or a fuzzy ball of probabilities? These evolving visual representations of the atom have long helped scientists understand the natural world and test their theories about it. But, they can also help explain complicated concepts to the public. As science and the world continue to increase in complexity, so the does need for clear communication—and since 2003, Science and the U.S. National Science Foundation have jointly sponsored a competition that rewards those who can do it effectively. Here’s Kerry with the story. Host – Kerry Klein Co-sponsored by the National Science Foundation and Science Magazine, the International Science & Engineering Visualization Challenge calls for innovative visual representations of scientific ideas. Open to anyone from academia to the private sector, the competition evaluates submissions based on their visual impact, originality, and clarity. To some, it’s as much an art contest as it is a scientific one.

Interviewee – Thomas Wagner On occasion now in science, you will see some amazingly creative ways of communicating ideas. And it could be, you know, fantastic artwork to communicate something complicated like the structure of the cell, it could be an amazing photograph, or it could be somebody who’s produced a video or a game to look at things. Host – Kerry Klein That’s Thomas Wagner, cryosphere program scientist for NASA. He’s been a Visualization Challenge judge for five years and has witnessed the evolution and revolution of science communication since the first Challenge in 2003. Interviewee – Thomas Wagner Every year we’re getting more and more submissions in the interactive and the games category. We’re also getting better and more sophisticated videos. But more importantly, I think because information technology tools and visualization tools have advanced, people have found ever-increasingly clever ways to display difficult scientific concepts. Host – Kerry Klein And this year’s winners, chosen from more than 200 submissions from 33 countries, cover quite a range of concepts—from a graphical representation of the distribution of matter in the universe, to an illustration of a tumor death-cell receptor that resembles a science fiction battle scene. But the area where the Challenge has seen the most dramatic change is in interactive games. The top competitors in that category include a firstperson adventure to save biologists stranded within a photosynthetic cell, as well as a protein-folding game that actually taps into real data on how proteins fold and behave. And this real-life data, Wagner says, is key. Interviewee – Thomas Wagner Now with the dawn of the information age, we have piles of data and be it anything from GPS or seismic stations around the world, through to, you know, molecular biological data. And what we saw in this competition was a few games came in where you actually got to go in as a user, manipulate data, and even contribute to research because you were creating new things, new geometries that hadn’t been seen before, that researchers could then test. Host – Kerry Klein The competition largely allows applicants to choose their own intended audience. Some frame their work for other experts in their field, some aim for the public at large, and many consider the impact of their visualizations in science classrooms—and that’s where innovation is important. Interviewee – Thomas Wagner When kids come into the classroom today, they’re familiar with, you know, video games where they move through a 3-dimensional world and their brains work a little bit differently. And by having these great visualizations it’s not only a way for us to get

them engaged and not make it seem boring, like dusty old maps, but also a way for them to really process it and really learn the concepts in a way that they’re used to. Host – Kerry Klein All in all, Wagner is excited about the future of science communication forecast by the entries in this challenge. Interviewee – Thomas Wagner And what I really like about these is that they show you the connections amongst things. They also point the direction that we’re going to be headed in. And I really think that the textbook of 2020 is going to look pretty different than the textbook of 2012 because of innovative work like this. Host – Kerry Klein To hear more about some of that innovative work, I spoke with Seth Cooper, a computer scientist and engineer at the Center for Game Science at the University of Washington. Cooper and a team of computer scientists and biochemists developed Foldit, this year’s 1st-place interactive game. Foldit uses the real data that Wagner values so heavily. Games today are mostly used for fun, but with this data, Cooper thinks they have the potential to bridge the gap between make-believe and real-life research. Interviewee – Seth Cooper Games are very good at engaging, and motivating, and even teaching people, so we can actually use games as a way to involve people in problem-solving. But rather than maybe trying to solve problems that were made up for the game world, we can actually work on solving different problems in the real world such as problems in science like protein folding. Host – Kerry Klein With Foldit, the participants fold proteins into new orientations and observe these molecules’ new behaviors. There are far too many possible orientations for a computer to model, plus, humans have their own analysis skills that computers can’t mimic—so, Cooper says, allowing users to manipulate proteins with a computer program is the best of both worlds. Interviewee – Seth Cooper The goal of the game is to actually combine what humans are good at—which is this high-level spatial reasoning and figuring out roughly how the pieces fit together—and what the computers are good at, which is doing, you know some of the number crunching and refinement to actually try to solve for these real, actual protein shapes in a way that we couldn’t do with just computers. Host – Kerry Klein So what are some of the real-life problems that the 240,000 Foldit users are contributing to?

Interviewee – Seth Cooper We’ve been working on puzzles that allow players to design things like flu inhibitors to help fight against disease, or protein enzymes, novel enzymes, that are more efficient at carrying out chemical reactions. Host – Kerry Klein If this sounds like some pretty serious research, it’s because it is—since Foldit’s creation in 2008, researchers have published 8 scientific papers from the game’s findings. And there’s a bonus for the players involved. Interviewee – Seth Cooper All the Foldit papers up to this point have included some members of the Foldit community as authors on the paper. Host – Kerry Klein In fact, a 2010 paper published in Nature included all 57,000 players at that time as contributors. But why stop there? Interviewee – Seth Cooper One of the grand goals for the project early on was to try to make a game where one of the players could, you know, conceivably, maybe, potentially win a Nobel Prize just through game play. Host – Kerry Klein Cooper and his team develop a lot of games, but he explains that their experience with Foldit has taught them a great deal—not just about how to bring users into research, but also about how to teach them. He says a few games geared towards science education are in the pipeline. However his next projects turn out, Cooper is optimistic about the future role of games in science. Interviewee – Seth Cooper I think that we’ll see more and more of, you know, games and citizen science and crowdsourcing and that kind of thing working its way throughout science and things like that. Host – Kerry Klein If educational tools are what you’re interested in, allow me to introduce Christopher Wilmer, a doctoral student in engineering at Northwestern University. He and his team of researchers, a high-energy narrator and his little brother, brought home an Honorable Mention for their video entitled, “High Density Energy Storage Using Self-Assembled Materials.” Now, that’s a mouthful—so let’s start with his research, which is primarily concerned with the self-assembly of porous materials. Interviewee – Christopher Wilmer The materials I investigate are assembled from trillions and trillions of identical molecules, so when they come together—they self-assemble—they form a perfect array of identically-sized pores. And by choosing these molecules appropriately, you get the

maximum possible amount of internal surface area which ultimately dictates how well these porous materials work. Host – Kerry Klein And the porous materials he coerces into self-assembling are generally used for manipulating gases, like capturing carbon dioxide from coal power plants and creating filters for gas masks. But this video discusses using these materials for a different sort of purpose: energy storage. Interviewee – Christopher Wilmer And the video tries to show how, for example, a material like this can be used to store natural gas in very large quantities at low pressures. Host – Kerry Klein It goes on to demonstrate how a computer program they created can help design fuel tanks that could store huge amounts of methane—enough to provide orders of magnitude more energy than the conventional gas tanks we find in cars today. No stranger to effective communication, Wilmer has always valued visual representations of his work. In this case, the video has certainly come in handy. Interviewee – Christopher Wilmer Basically anytime people in my area get asked, you know, what do you do, what’s your research about—by their friends who aren’t in the sciences—rather than trying to explain it, now they tend to send them a link to this Youtube video. Host – Kerry Klein The overwhelmingly positive response to the video hasn’t just come from Wilmer’s family and friends, but also from fellow scientists and even students who approach him with a new-found interest in his work. Interviewee – Christopher Wilmer There’s always a worry that I’m spending more time on communicating my research than doing my research, but because the response to making this movie has been so positive, that has motivated me to in the future spend the effort on communicating the research. Host – Kerry Klein By the time I spoke with Wilmer, his video had been viewed on YouTube around 2,800 times… Interviewee – Christopher Wilmer …which, you know, is not as much as any video on cats… Host – Kerry Klein …but which is likely to increase with the announcement of his award. Now, Wilmer and Cooper are just two of the many winners of this year’s Visualization Challenge. So be

sure to watch, read, and play all of the other winning submissions on the Science Magazine website—and maybe you’ll learn something. For Science, this is Kerry Klein. Host – Sarah Crespi Kerry Klein reports on this week’s announcement of the winners of the 2011 International Science and Engineering Visualization Challenge. To view the winners and runners up, visit www.sciencemag.org/special/vis2011. Music [27:19] Interviewer - Sarah Crespi Finally today, David Grimm, online news editor of Science, is here to give us a rundown of some of the recent stories from our daily news site. First, we have a story on the unique properties of spider silk. Interviewee - David Grimm Right. Sarah, this story is all about what makes spiderwebs so flexible and yet so strong. Interviewer - Sarah Crespi So it’s more than just the composition of the silk – it’s also the arrangement of the fibers? Interviewee - David Grimm It is. What researchers already knew is they knew that spider silk is very unusual. If you can imagine a spider dangling from a single thread from the ceiling – and I’m sure a lot of us have seen that – if you actually pulled on the thread it would be elastic for a little while, but if you kept on pulling it would actually stiffen up again, which is really unusual. And researchers knew that during the elastic stage, there’s proteins in the spider silk that are scrunched into these intricately folded structures, and pulling on the silk actually disentangles these structures. And when there’s no more knots to untie, the proteins reconfigure into tough structures called beta-sheet nanocrystals, and that’s what makes the silk get stiff again when you continue to pull it. So they already knew that, but they didn’t was how this worked on a web-wide level. You know, webs are much more than just hanging pieces of silk – they’re very intricate designs, there’s a lot of spokes, and a lot of other stuff going on in the web. And so the researchers wanted to figure out what’s happening sort of on the web-wide level that’s allowing these webs to be so flexible and so strong. Interviewer - Sarah Crespi And they did this in a pretty neat way. Interviewee - David Grimm Yeah, they did, Sarah. Basically what they did was they actually went into the wild, and they found some spiderwebs, and they hung these tiny weights from them to approximate a fly getting stuck in the web. And they wanted to see what happened when individual spokes in the web stretched so much that they snapped. And what they found is when

this happened other threads wouldn’t break with them, so it was just the individual spokes that snapped. And they found that even when 10% of the spokes snapped, the web still retained its original strength. But they weren’t satisfied just with going out into the wild – they actually wanted to run some computer simulations, as well. And they fed a bunch of web designs and different elasticities into a computer. And they found that what it really is that makes spider webs so amazing is that they can be stretchy or stiff at different times, and that produces threads that flex and then snap in just the right way to avoid wrecking enough spokes that would really damage the integrity of the web as a whole. Interviewer - Sarah Crespi So spiders can preserve their web through some insect-based damage. What about an application for this more generally? Interviewee - David Grimm Well, right. Well, one of the reasons researchers are so interested in spider webs is because they are such unusually strong, flexible materials. And scientists are always interested in taking nature and making co-applications from it. And so one of the researchers actually wants to genetically engineer spiders so that they can spin threads with properties not even seen in nature that are even more amazing than what we see currently. And one can only guess at what kind of applications that could have. So stay tuned for genetically engineered spiders. Interviewer - Sarah Crespi I will. So the next story is more about how plants have been engineering the planet. They might have triggered an ice age? Interviewee - David Grimm That’s true. This next story is all about an unusual relationship between plants and global climate. Now what the history is here, is about 460 million years ago the concentration of carbon dioxide in the atmosphere was very high – it was about 14 to 22 times higher than it is today. And this created a world that was about 5° on average warmer than it is today, so it was a very hot place to be. And then something unusual happened. About 455 million years ago, Earth experienced two major glaciations – a lot of the land on the planet was actually covered in ice. And the only way this could have happened is if there was a dramatic reduction in the amount of carbon dioxide in the atmosphere. Carbon dioxide is a greenhouse gas, so it traps a lot of heat. The less carbon dioxide you have in the atmosphere, the colder the planet is going to be. But researchers haven’t been able to figure out what caused such a dramatic drop in carbon dioxide. Interviewer - Sarah Crespi So was it actually plants taking that up out of the air or is there more to the story? Interviewee - David Grimm There’s actually more to the story. That’s what I would have suspected, as well. But it turns out that this actually has a lot to do with the weathering of rocks. The weathering

actually allows them to pull carbon dioxide from the atmosphere. And this forms minerals that actually trap the carbon, keeping it out of the air, and the Earth gets cooler. But the problem is that this weathering doesn’t happen fast enough to have accounted for this dramatic drop in temperature that happened 455 million years ago. So something else may have been playing a role. And that’s where plants come in. And what scientists have shown in the lab is that some of the earliest land plants actually weathered a lot of these rocks very quickly and allowed the rocks to take up a lot of carbon. And they show this by actually putting a bunch of rocks in sealed beakers inside the laboratory, and they added some moss – specifically a modern-day species of moss that’s believed to be very similar to some of the first land plants. And what they found was that the presence of the moss significantly increased the weathering of the rocks. And what they did next was they actually fed all of this data into a climate model, and they found that if these land plants covered about 15% of Earth’s surface, which is what scientists have assumed, they would have weathered enough rocks to have resulted in a drastic decrease in carbon dioxide – enough of a decrease to have resulted in the major cold snap that was seen 455 million years ago. Interviewer - Sarah Crespi So this wasn’t the only time this has happened, right? Interviewee - David Grimm Right. In fact, there was another major glaciation about 10 million years after this first glaciation. And the scientists say that what may have been responsible for that was actually not the mosses but another group of plants known as vascular plants, and today’s vascular plants are plants like ferns and flowering plants, which similarly may have weathered rocks and caused another dramatic drop in carbon dioxide levels. Interviewer - Sarah Crespi Okay. Last we have a mechanism for massage and why it makes us feel better. Interviewee - David Grimm Right. Well, we all know – any of us that have had a massage – that massage feels good. It actually turns out it seems to do good, as well. Studies have shown that it actually does relieve pain and seems to relieve inflammation. But scientists don’t know how – or at least they didn’t know how until this new study came around. There was some speculation that maybe massage squeezes lactic acid, which is this byproduct of exertion that can cause sore muscles – literally squeezes it out of the muscles. Or maybe it somehow filters other waste products out of the muscles, and that helps us heal faster and makes us feel better. But nobody was really sure what was going on until this new study came along. Interviewer - Sarah Crespi And so they found some people who are willing to exercise for science?

Interviewee - David Grimm Right. Eleven young men – they put them on these grueling upright bicycles and made them basically workout until they were completely exhausted and completely sore. And then they had a massage therapist come in and only massage one of their legs. So I’m sure the other leg didn’t feel so good. And before, during, and after the experiments they actually took tissue samples from the legs of all of the volunteers, and they compared the legs that got massaged to the legs that didn’t get massaged. So the first thing they saw, which wasn’t terribly surprising, was they saw a lot more inflammation in the postworkout samples than the pre-workout samples. And, when we exercise a lot and we damage our muscles, which happens during exercise, obviously you’re going to get a lot more inflammation. They also saw a lot more signs of cell repair going on. So that wasn’t surprising. But when they compared the two legs of each guy to each other, what they found was they found these big differences in a couple of genes – one is called PGC1-alpha, which is a gene that helps muscle cells build mitochondria, which are the engines that turn the cell’s food into energy. And massaged legs also have three times less NFkB, which turns on genes that is associated with inflammation. So there was these big molecular differences going on between the legs that got massaged and the legs that didn’t. Interviewer - Sarah Crespi So they saw more healing, less inflammation after the massage? Interviewee - David Grimm Exactly. And what they didn’t see, which was also kind of surprising, they didn’t see any evidence that massage removed lactic acid or any other waste products. So it doesn’t seem like the traditional view of why massage works actually holds up, but there’s actually a much more interesting thing going on. Interviewer - Sarah Crespi Myth busted. Interviewee - David Grimm Right. Interviewer - Sarah Crespi Well, David, what else do we have on the site for this week? Interviewee - David Grimm Well, Sarah, for ScienceNOW we’ve got a story about how giant storms can churn the water even in the very deep sea. Another story about why dinosaurs got so big. For ScienceInsider, we’ve got a story about why thousands of scientists are boycotting a major academic publisher. Also a story about the current crop of Republican presidential candidates in the United States and what their stances are on science. Finally, for ScienceLive, our weekly chat on the hottest topics in science, this week’s chat is about peak oil – is the world’s oil supply running dry? And next week’s chat is about the

science of love timed just a few days before Valentine’s Day. So be sure to check out all of these stories on the site. Interviewer - Sarah Crespi I will. Thanks, David. Interviewee - David Grimm Thanks, Sarah. Interviewer - Sarah Crespi David Grimm is the online news editor for Science. You can check out the latest news and the policy blog, ScienceInsider, at news.sciencemag.org where you can also join a live chat, ScienceLive, on the hottest science topics every Thursday at 3 p.m. U.S. Eastern time. Music Host – Kerry Klein And that concludes the February 3rd, 2012 edition of the Science Podcast. Host – Sarah Crespi If you have any comments or suggestions for the show, please write us at [email protected]. Host – Kerry Klein The show is a production of Science Magazine. Jeffrey Cook composed the music. I'm Kerry Klein. Host – Sarah Crespi And I’m Sarah Crespi. On behalf of Science Magazine and its publisher, AAAS, thanks for joining us. Music ends