Click here to view the embedded video.
This attempt at a balloon launch ended in disaster for NASA. Apparently the balloon was trying to carry a payload of telescopes. I hate to see these failures, still I find it difficult to suppress a chuckle – sorry.
On May 18, the Japan Aerospace Exploration Agency (JAXA) says, it will launch into space a “solar yacht” called Ikaros—the Interplanetary Kite-craft Accelerated by Radiation of the Sun (named, of course, in honor of Icarus in Greek mythology). JAXA plans to control the path of Ikaros by changing the angle at which sunlight particles bounce off the silver-coloured sail [AFP].
Actually, the solar sail is a dual-purpose system, taking advantage of both the pressure and the energy of sunlight. The sail, which is less than the thickness of a human hair and 66 feet in diagonal distance, will catch the actual force of sunlight for propulsion as a sailboat’s sail catches the wind. But the solar sail is also covered in thin-film solar cells to generate electricity. And if you can make electricity, you can use it to ionize gas and emit it at high pressure, which is the propulsion systems most satellites use.
Potential velocity using a solar sailor has been theorized to be extremely high. “Eventually you’ll have these missions lasting many years, reaching speeds approaching 100,000 mph, getting out of the solar system in five years instead of 25 years,” said Louis D. Frieman, the Executive Director of the Planetary Society [Clean Technica]. The society has toyed around with its own solar sail.
For now, though, JAXA has a six-month test mission planned for Ikaros. If it works, they want to send a solar sail-powered mission to Jupiter and then the Trojan asteroids. That voyage would employ both the force of the sun and ion propulsion, and the Japanese are brimming with confidence: “Unlike the mythical Icarus, this Ikaros will not crash,” Yuichi Tsuda, an assistant professor at JAXA, said today [BusinessWeek].
Related Content:
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80beats: Spacecraft That Sails on Sunshine Aims For Lift-Off in 2010, on the Planetary Society’s own attempts at a solar sail.
DISCOVER: Japan Stakes Its Claim in Space
DISCOVER: One Giant Step for a Small, Crowded Country, on Japan’s moon aspirations
DISCOVER: Japan Sets Sail in Space
Image: JAXA
Friends for better or for worse: interracial friendship in the United States as seen through wedding party photos. "Friendship patterns are instrumental for testing important hypotheses about assimilation processes and group boundaries. Wedding photos provide an opportunity to directly observe a realistic representation of close interracial friendships and race relations. An analysis of 1,135 wedding party photos and related information shows that whites are especially unlikely to have black friends who are close enough to be in their wedding party. Adjusting for group size, whites and East and Southeast Asians (hereafter E/SE Asians) are equally likely to be in each other's weddings, but whites invite blacks to be in their wedding parties only half as much as blacks invite whites, and E/SE Asians invite blacks only one-fifth as much as blacks invite E/SE Asians. In interracial marriages, both E/SE Asian and black spouses in marriages to whites are significantly less likely than their white spouses to have close friendships with members of their spouse's race." Image: flickr/Bludgeoner86 Related content:
Discoblog: NCBI ROFL: And September's "No shit, Sherlock" award goes to…
Discoblog: NCBI ROFL: I’d like a number 2 value meal, a frosty, and a peer-reviewed publication, please.
Discoblog: NCBI ROFL: The teddy-bear effect: does having a ...
This is awful: during the launch of a high-altitude balloon, something went wrong. The balloon dragged the payload across the ground, destroying it, and in the meantime not doing any good to an SUV parked nearby:
This happened yesterday, in Australia. No one was hurt, but the payload apparently was totaled. It looks to me that the balloon got caught by some wind before they were quite ready to launch, and it pulled the payload off the crane. Seeing what it did to that SUV… yikes.
The balloon was carrying gamma-ray detectors as a testbed for a future NASA observatory. Gamma rays don’t penetrate the Earth’s atmosphere, so observatories have to be launched into space. The detectors on-board can be tested on the ground, but at some point need to get up above as much of the atmosphere as possible to see how they do in those conditions and observing actual astronomical sources. Balloons are the easiest and cheapest way to do that.
I know some folks who have done balloon launches like this, and they’ve told me it can be a little hairy. I trusted them, but until I saw that payload smash into and flip over that truck, I didn’t fully realize what they meant. Wow.
This is a setback for NASA and the team building the observatory. I don’t know how much, exactly, but I’m sure it will be months or even years to rebuild this. I can’t imagine much will be salvaged off this disaster.
I saw this earlier today, but no video was available to embed. So thanks to Tom’s Astronomy blog where I saw this, and Discovery News where I first heard about it.
It’s an earthworm so mysterious, people compare it to the Loch Ness Monster. Rarely sighted since the 1980’s, the giant Palouse earthworm was said to grow almost three feet long, smell like lilies, and spit at predators. It was so elusive, that some even doubted its existence–but now, a team of conservationists from the University of Idaho has found several of these mysterious creatures in a prairie field.
But what a let down it was.
Contrary to popular claim, the earthworms did not smell like lilies or spit at their predators. They weren’t even particularly giant, causing lead researcher Jodi Johnson-Maynard to remark: “One of my colleagues suggested we rename it the ‘larger than average Palouse earthworm’” [The Telegraph].
The team started combing the prairie region between Idaho and Washington state last summer in search of the Palouse earthworms. It was researcher Karl Umiker who eventually struck gold–or in this case, worm. Umiker used a tool called an electroshocker, in which electricity is passed through a number of electrodes that are stuck in the soil. Umiker was “shocking” a fragment of unploughed prairie when two giant earthworms emerged from the soil–a juvenile and an adult.
The Palouse worms were said be abundant in the 19th century, but farming of the prairie land reduced their numbers drastically. The worms were considered extinct until 2005, when Idaho graduate student Yaniria Sanchez-de Leon found a specimen near Albion, Wash. But that worm had been cut nearly in half as she was digging a hole [AP]. It’s not clear whether the worms retrieved last month were part of tiny population of remaining worms, or whether they’re considered rare simply because they live deep in the soil (down to 15 feet below the surface) and flee from the vibrations caused by digging scientists.
When they were extracted from the soil, both worms were about seven inches long. Says Johnson-Maynard: “But when we stretched it out and relaxed it, the adult earthworm got bigger…. It’s between 9 and 10 inches” [The New York Times]. That’s still a far cry from the myth of 3-foot-long Palouse worms. Johnson-Maynard says that legend may have arisen from reports of one truly giant specimen recovered many years ago. “Apparently some boy was swinging it in the air like a rope, and it stretched” [The New York Times].
Johnson-Maynard confirmed that the worms did not smell like lilies either, saying, “I have a fairly sensitive nose, and I just can’t smell the lily” [NPR]. The researchers have also seen no evidence of spitting.
While the adult was killed in order to confirm whether it was indeed a Palouse earthworm, researchers are excited to still have the juvenile alive and in one piece. For now, the captured juvenile is resting comfortably, Dr. Johnson-Maynard said, adding, “We have it in a cooler in soil with ice packs” [The New York Times].
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Discoblog: Worms Are Picky Ejaculators
Discoblog: Worm Grunting Mystery Solved…by Darwin
Discoblog: New “Worm Charming” Champion Sets World Record
Image: University of Idaho
Amy Roth — that’s Skepchick Surly Amy to you — interviewed Cassini tour designer John Smith. It’s part of a new segment on Skepchick called Keep your day job:
Amy is a cool chick: artistic, skeptical, tattooed, photographically inclined, and loves astronomy. I got to hang with her and other skepchicks last week in Pasadena, and life is always better when that happens.
Having the power shut off in your home due to lack of payments can really motivate you to pay your bills—or perhaps to begin siphoning electricity with a meat hook. A recent report from Reuters describes a middle-aged man in Germany who has been stealing electricity from a high-voltage overhead transmission line using a run-of-the-mill meat hook. After getting cut off by the power company for not paying his bills, the energy thief decided he would acquire the necessary power on his own; he attached a meat hook to the end of a long cable, and hurled the hook onto an overhead power line 150 meters from his house. By routing some of the electricity to his meter box, the man powered his home illegally for an entire month before anyone noticed. Now before you run off to Home Depot to buy cable and meat hooks (do they sell meat hooks at Home Depot?), you should be aware that siphoning electricity is not only illegal, it's also insanely dangerous. A report from the Australian Broadcasting Corporation noted the recent death of a man who was electrocuted from trying to siphon off power for an illegal drug lab. And utility employee Friedrich-Wilhelm Lach ...
I’m reading an interesting new book, Bursts by Albert-Laszlo Barabasi. It’s just released today, but I scored an advance copy by virtue of sharing the same publisher. The basic idea is simple: human behavior obeys power laws! That is, things we occasionally do tend to be clustered together, rather than simply occurring with uniform probability. I can’t vouch for either the truth or usefulness of the claims put forward in the book; we all know that power laws can be slippery things. But the stories related along the way are pretty amusing. (And there’s a very spiffy web page.)
I’ll admit that I jumped right to a chapter in the middle that relates the correspondence between Einstein and Theodor Kaluza in the year 1919 and thereabouts. Kaluza had just come up with the idea that electromagnetism could be unified with gravity by hypothesizing an extra dimension of space — a scenario now known as Kaluza-Klein theory, which underlies all the contemporary excitement about extra dimensions of space. Many crackpots like to assert that our contemporary system of scientific publishing is overly ossified and hierarchical, and that a modern-day Einstein would never be appreciated; the truth is close to the opposite, as back in those days you really needed endorsement from someone established to get your papers published. So Kaluza wrote to Einstein, who was originally enthusiastic about the idea, and they had a flurry of correspondence. Eventually (as I now know) Einstein cooled on the idea, and Kaluza left physics to concentrate on pure mathematics. A couple of years later, after getting nowhere with his own attempts to unify gravity and E&M, Einstein turned back to Kaluza’s approach, and wrote him again, offering to present his paper to the academy.
The book’s interest is actually in the “burstiness” of the correspondence — a flurry of letters back and forth in 1919, then silence, then the conversation resumed in 1921. I was struck by this paragraph, relating the growth of Einstein’s celebrity after the eclipse expedition of 1919 provided evidence supporting general relativity.
[Einstein's] sudden fame had drastic consequences for his correspondence. In 1919, he received 252 letters and wrote 239, his life still in its subcritical phase, allowing him to reply to most letters with little delay. The next year he wrote many more letters than in any previous year. To the flood of 519 he received, we have record of his having managed to respond to 331 of them, a pace, though formidable, insufficient to keeping on top of his vast correspondence. By 1920 Einstein had moved into the supercritical regime, and he never recovered. The peak came in 1953, two years before his death, when he received 832 letters and responded to 476 of them.
Can you imagine what Einstein would have faced in the email era? One thing is for sure: he was a champion correspondent. He composed approximately 14,500 letters, more than one per day over the course of his adult life.
Not for the first time, Einstein makes me feel like a slacker.
If you’re in LA this weekend, and you love SciFi and mad scientists — and c’mon, who doesn’t? — then you’ll want to attend the screening of "Monsters from the Id", a documentary on mad scientists, 1950s movies, and the future of science in the US. Seriously, check this video out and tell me you don’t want to see this:
There will be a panel after the screening, talking about these topics as well. That trailer hits all the right notes, and features some of my favorite movies of all time ("War of the Worlds", "Them!", "The Day the Earth Stood Still", "The Thing from Another World", "Forbidden Planet", und so weiter). Man, I wish I could go, but I don’t think I can make it. But don’t let that stop you. Put down the Krell brain enhancing machine and get moving!
What does a one-in-ten-million chance of apocalypse look like? Well, it used to look like this:
That is asteroid 2005 YU55, a near-Earth object (or NEO) that also happens to be a PHA, or potentially hazardous asteroid. It has an orbit which intersects the Earth, which means that someday it could possibly hit us.
Now before you panic — and I’ll make this clear: DON’T PANIC — that doesn’t mean you’ll wake up tomorrow to see flaming death streaking across the sky. Think of it this way: when you walk to the local convenience store to get a squishy, you have to cross the street. The path you take intersects the street, but as long as you don’t try to occupy the same spot as a moving car, you won’t get hit. Same with PHAs: their orbits cross the Earth’s orbit, but space is big. As long as the Earth and the asteroid aren’t at the same place at the same time, we’re OK.
Since we don’t know the orbits of these objects perfectly, we assign a probability they will hit us over some period of time. Up until recently, YU55’s chance of hitting us over the next century was calculated to be about 1 in 10,000,000, which is reasonably close enough to 0 for me. However, it’s always good to get better data. In this case, very good: new observations have eliminated the chance that YU55 will ruin our day for at least a century to come.
YU55 was observed with the monster 300 meter (1000 foot) Arecibo radio telescope in Puerto Rico. Arecibo can send little radar pings into space, aimed at an asteroid. The pings reflect off the rock, come back to Earth, and the timing of each one can be logged. This tells us how far away the asteroid is, how big it is, and even (by carefully measuring the different arrival times of the pings back on Earth) the shape of the asteroid.
If this sounds familiar, that’s because this is how dolphins and bats sense their environment. They use sound, not light, but the principle is the same. So what did Arecibo tell us when it dolphinated YU55?
The good news is that the orbit of the asteroid was nailed down better, and that 1 in 10,000,000 chance of an impact in the next century dropped to 0. Nada. Nil. And astronomers are so confident of that they removed YU55 from their Risk Page.
So we’re safe from YU55 ruining our day for quite some time at least.
And that’s good, because, as it turns out, YU55 is bigger than expected: about 400 meters (a quarter mile) across, twice as large as previous estimates showed! Something that big hitting us at orbital speeds would explode with the force of a lot of nuclear weapons — a few thousand megatons, or a hundred times the yield of the largest bomb ever detonated.
So yeah, yay! It won’t hit us, and that’s by any definition good.
But the middlin’ bad news is that this also means is that it’s tough to get good size estimates for asteroids without this technique. Usually, the size of a rock is determined by measuring how bright it is. A bigger asteroid reflects more light, and by measuring how well it reflects sunlight we can estimate the size. But that doesn’t always work so well, as YU55 is telling us. Clearly, we need to use multiple methods to get the sizes of these guys.
Arecibo’s funding is constantly under attack, yet it’s the best machine we have to get the sizes of and, more importantly, accurate orbits for these potentially life-threatening objects. YU55 is off the list now, but there’s a long line of rocks ready and waiting to take its place there.
There used to be a time when you could easily impress a date by pointing to the night sky and dreamily rattling off names of major stars, constellations, and the like. Now, instead of cramming your head full of names or making up stuff as you go along, you can use your trusty iPhone to guide you through your stargazing. There are a bunch of apps that you can download, depending on your interest level and degree of expertise. Most of the apps are based on augmented reality--so all you have to do is point your phone towards the sky and the app does the rest. If you're a beginner, Pocket Universe ($3) and Star Walk ($3) are recommended by The New York Times for iPhone users; while Google Sky Map is great for Android users. With Pocket Universe, you can use the camera view to look at the evening or morning sky, and the app will overlay the labeled view over the real sky. (The iPhone's camera isn't good enough yet to pull off this feat with a dark night's sky.) The app also plots the position of the sun, moon, and planets, displays 10,000 stars, and traces the shapes of the ...
Clench your left hand into a fist. What happened to your right hand when you did it?
If you’re like most people, the answer is nothing. But, surprisingly, not everyone can do this. Some people make “mirror movements”, where moving one side of the body, particularly the hands, causes the other to move unintentionally. Clench the left fist, and the right one closes too. Doing things like playing the piano or typing are very difficult. In 2002, a Chinese man with the disorder failed to get into the military because he couldn’t use the monkey bars.
Young children sometimes make mirror movements but they almost always grow out of it by the age of 10. The only exceptions tend to be people with rare genetic disorders of the nervous system, like Klippel-Feil and Kallmann syndromes. Now, Myriam Srour from the University of Montreal has found that a single faulty gene can cause the condition.
She studied a large French Canadian family with four generations of members who had been making mirror movements from birth. Not everyone was affected, and the pattern of the disorder strongly suggested that a single dominant genetic fault was responsible. Srour tracked it down by comparing the genomes of affected and normal family members, and her search led her to a short area on the 18th chromosome, which contained three genes.
One of these genes is called DCC and it turned out to be the true culprit behind the disorder. In the Canadia family, those who make mirror movements have a version of DCC with a single altered DNA ‘letter’. This tiny fault means that the protein encoded by DCC is manufactured with a missing chunk. That chunk happens to include many of the most important segments of the DCC protein, which, in its abridged form, is completely useless.
Srour found this mutation in every case of mirror movements, and never in 760 unrelated people whose left and right sides are typically independent. To confirm DCC’s role, she turned to an Iranian family, many of who also demonstrated the quirk from birth. She sequenced their DCC genes and again, she found that those who make mirror movements had broken copies. In this case, the mutation was different but the result was the same – a shortened and ineffectual protein.
It’s not just humans who are affected in this way. If mice have mutated and shortened copies of DCC, they too show mirror movements and they move with a distinctive hopping gait. These strains are affectionately known as Kanga mice. If they lack any copies of the gene entirely, their problems are more severe. The gap between the brain’s hemispheres doesn’t develop properly and the fibres that connect the two halves– the corpus callosum – are fewer in number and misrouted.
These mutant mice hint at DCC’s role. The DCC protein is a docking bay (a receptor) for another protein called netrin-1, whose role is to guide the neurons of the developing nervous system across the midline of the body. Its name even comes from the Sanskrit word “netr”, meaning “one who guides”. But this neural shepherd can’t stick to broken DCC proteins and without its good work, the neuronal connections between the body’s two halves don’t form properly.
Reference: Science http://dx.doi.org/10.1126/science.1186463
More on genetic disorders:
This is a guest post by Darlene Cavalier, a writer and senior adviser at Discover Magazine. Darlene holds a Masters degree from the University of Pennsylvania, and is a former Philadelphia 76ers cheerleader. She founded ScienceCheerleader.com and cofounded ScienceForCitizens.net to make it possible for lay people to contribute to science. Happy Thursday. Very pleased to be filling in for Sheril this month. These are big shoes to fill, to say the least. During my time with you, I hope my writings provide a bit of inspiration, provocation, or, failing that, some entertainment to brighten your day. All I ask in return is that you keep doing what you do so well here: share your ideas and comments. Some of you (two, three?) may know me as the Science Cheerleader, a persona who advocates--and creates mechanisms--for public participation in science and science policy. These are broad terms with multiple definitions, depending on the author's intention. Let's dive right into one of this author's intentions: to create a way for citizens and experts to participate in assessments of emerging technologies. Citizens, your time has come! On this day in history, Aretha Franklin released her hit song, Respect. And on THIS day, respect for your ...
There are millions of asteroids in the asteroid belt between Mars and Jupiter, but yesterday attention focused on just one. According to a couple of studies in Nature, a large asteroid called 24 Themis is rife with water ice and organic molecules, and the researchers say that it could be more evidence that the water so precious to life on Earth came to our planet on board such rocks.
Two research teams took infrared images of 24 Themis, which is about 120 miles in diameter and was discovered in 1853. This asteroid has an extensive but thin frosty coating. It is likely replenished by an extensive reservoir of frozen water deep inside rock once thought to be dry and desolate [AP].
The team, led by Humberto Campins, says finding so much ice on the surface was a surprise; at the asteroid’s distance from the sun—3.2 astronomical units (AU), or just more than three times further than the Earth—exposed ice has a “relatively short lifetime,” the scientists write. As a result, the idea of a below-surface reservoir seems likely. (Icy comets aren’t nearly so close to the sun on average; Halley’s comet can come within .6 AU of the sun, but then retreats to a farthest distance of more than 35 AU.)
It might seem implausible that our planet’s water supply arrived incrementally as cargo on board comets or asteroids. But here’s how it may have happened: More than four billion years ago, after a massive collision between Earth and another large object created the moon, our planet was completely dessicated. Then, during the Late Heavy Bombardment period that followed, during which lots of asteroids hit Earth, the ice that the objects carried became our store of water [Wired.com]. The bombardment period, which occurred nearly 4 billion years ago, was largely responsible for our moon’s puckered appearance. A 2005 Nature study estimated that between 3 and 8 zettagrams of material slammed into the moon during that time (zetta means 10 to the 21st power, or a billion times a trillion), which implies that plenty of rocks slammed into the Earth, too.
Asteroids just keep getting more interesting. As we noted on Monday, the Japanese spacecraft that touched down on an asteroid is limping home to Earth, hoping to return its results (and maybe an asteroid sample) to the home world by June. And President Obama’s revised space exploration plan includes the idea for astronauts to visit an asteroid—a possibility that’s all the more scientifically enticing if they were the bringers of our water.
Related Content:
DISCOVER: Did An Early Pummeling of Asteroids Lead to Life on Earth?
80beats: Did An Asteroid Strike Billions of Years Ago Flip the Moon Around?
80beats: Our Alien Atmosphere? Earth’s Gases May Have Arrived Here Aboard Comets
80beats: Danger, President Obama! Visiting an Asteroid Is Exciting, But Difficult
Image: NASA
Over the last few days, estimates had held that the Gulf of Mexico oil spilling was leaking about 1,000 barrels, or 42,000 gallons, into the water each day—bad, but still not historically bad on a scale like the spill caused by the Exxon Valdez. Except now, after closer investigation, the National Oceanic and Atmospheric Administration says that oil company BP’s estimate might in fact be five times too low.
Rear Adm. Mary Landry, the Coast Guard’s point person, gave the new estimate yesterday as the Coast Guard began its planned controlled burn of some of the oil. While emphasizing that the estimates are rough given that the leak is at 5,000 feet below the surface, Admiral Landry said the new estimate came from observations made in flights over the slick, studying the trajectory of the spill and other variables [The New York Times]. Because the oil below the surface is so hard to measure or estimate, NOAA’s numbers are still rough estimates, too. BP’s chief operating officer told ABC News he thinks the number is probably somewhere between the two estimates.
But if NOAA’s high-end number right, the oil spill caused by the explosion and sinking of the Deepwater Horizon just entered a new class of awful. Do the math: At the previous estimation—1,000 barrels (42,000 gallons) of oil per day—it would have taken this spill 261 days, or more than eight continuous months, to dump as much oil into the sea at the Exxon Valdez did near Alaska in 1989. But, if it’s true that 5,000 barrels (210,000 gallons) are entering the Gulf each day, it would take just 53 days to top the Valdez’ total of 11 million gallons. Already 9 days have passed since the explosion.
While the Coast Guard commenced burning off some of the oil to try to keep the worst of it away from American shorelines, and BP’s attempted to reach emergency valves with undersea robots, company CEO Tony Hayward is preparing a new strategy. The London-based Hayward was in Louisiana on Wednesday looking at progress in fabricating a 100-ton steel dome the company hopes to lower over the oil leak. The dome could be ready by the weekend, but it would take two to four weeks to put it in place, if that can be done at all. The dome would funnel oil, natural gas and seawater into a pipe leading to a floating processing and storage facility [Washington Post]. But while this has been done in a few hundred feet of water before, the Gulf oil spill emanates from thousands of feet below.
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80beats: Ships Race To Contain the Gulf of Mexico Oil Spill
80beats: Obama Proposes Oil & Gas Drilling in Vast Swaths of U.S. Waters
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Image: NOAA
After years of serving as your faithful companion to ball games and keeping the brewskies frosty at backyard barbecues, your trusty beer cooler now has a new assignment--cooking up a gourmet meal, sous-vide style. For those of you who don't keep up with high-tech cookery, sous-vide is a method of cooking where food is heated for an extended period at relatively low temperatures. Unlike a slow cooker or Crock pot, the sous-vide process uses airtight plastic bags placed in hot water well below boiling point (usually around 140 Fahrenheit). The idea is to maintain the integrity and flavor of the food without overcooking it (but while still killing any bacteria that may be present). Normally, a sous-vide cooker like the Sous-Vide Supreme would set you back hundreds of dollars, but chef J. Kenzi Lopez-Alt shows us how to use a beer cooler to cook a perfect piece of meat. All you have to do is fill up your beer cooler with water a couple of degrees higher than the temperature you'd like to cook your food at (to account for temperature loss when you add cold food to it), seal your food in a simple plastic Ziplock bag, drop it in, and close ...
Change is quite in the air today, whether it be climate change or human induced habitat shifts. What’s a species in the wild to do? Biologists naturally worry about loss of biodiversity a great deal, and many non-biologist humans rather high up on Maslow’s hierarchy of needs also care. And yet species loss, or the threat of extinction, seems too often to impinge upon public consciousness in a coarse categorical sense. For example the EPA classifications such as “threatened” or “endangered.” There are also vague general warnings or forebodings; warmer temperatures leading to mass extinctions as species can not track their optimal ecology and the like. And these warnings seem to err on the side of caution, as if populations of organisms are incapable of adapting, and all species are as particular as the panda.
That’s why I pointed to a recent paper in PLoS Biology, Adaptation, Plasticity, and Extinction in a Changing Environment: Towards a Predictive Theory below. I am somewhat familiar with one of the authors, Russell Lande, and his work in quantitative and ecological genetics, as well as population biology. I was also happy to note that the formal model here is rather spare, perhaps a nod to the lack of current abstraction in this particular area. Why start complex when you can start simple? Here’s their abstract:
Many species are experiencing sustained environmental change mainly due to human activities. The unusual rate and extent of anthropogenic alterations of the environment may exceed the capacity of developmental, genetic, and demographic mechanisms that populations have evolved to deal with environmental change. To begin to understand the limits to population persistence, we present a simple evolutionary model for the critical rate of environmental change beyond which a population must decline and go extinct. We use this model to highlight the major determinants of extinction risk in a changing environment, and identify research needs for improved predictions based on projected changes in environmental variables. Two key parameters relating the environment to population biology have not yet received sufficient attention. Phenotypic plasticity, the direct influence of environment on the development of individual phenotypes, is increasingly considered an important component of phenotypic change in the wild and should be incorporated in models of population persistence. Environmental sensitivity of selection, the change in the optimum phenotype with the environment, still crucially needs empirical assessment. We use environmental tolerance curves and other examples of ecological and evolutionary responses to climate change to illustrate how these mechanistic approaches can be developed for predictive purposes.
Their model here seems to be at counterpoint to something called “niche modelling” (yes, I am not on “home territory” here!), which operates under the assumption of species being optimized for a particular set of abiotic parameters, and focusing on the shifts of those parameters over space and time. So extinction risk may be predicted from a shift in climate and decrease or disappearance of potential habitat. The authors of this paper observe naturally that biological organisms are not quite so static, they exhibit both plasticity and adaptiveness within their own particular life history, as well as ability to evolve on a population wide level over time. If genetic evolution is thought of as a hill climbing algorithm I suppose a niche model presumes that the hill moves while the principal sits pat. This static vision of the tree of life seems at odds with development, behavior and evolution. The authors of this paper believe that a different formulation may be fruitful, and I am inclined to agree with them.
As I observed above the formalism undergirding this paper is exceedingly simple. On the left-hand side you have the variable which determines the risk, or lack of risk, of extinction more or less, because it defines the maximum rate of environmental change where the population can be expected to persist. This makes intuitive sense, as extremely volatile environments would be difficult for species and individual organisms to track.Too much variation over a short period of time, and no species can bend with the winds of change rapidly enough. Here are the list of parameters in the formalism (taken from box 1 of the paper):
?c – critical rate of environmental change: maximum rate of change which allows persistence of a population
B – environmental sensitivity of selection: change in the optimum phenotype with the environment. It’s a slope, so 0 means that the change in environment doesn’t change optimum phenotype, while a very high slope indicates a rapid shift of optimum. One presumes this is proportional to the power of natural selection
T – generation time: average age of parents of a cohort of newborn individuals. Big T means long generation times, small T means short ones
?2 – phenotypic variance
h2 – heritability: the proportion of phenotypic variance in a trait due to additive genetic effects
rmax intrinsic rate of increase: population growth rate in the absence of constraints
b – phenotypic plasticity: influence of the environment on individual phenotypes through development. Height is plastic; compare North Koreans vs. South Koreans
? – stabilizing selection: this is basically selection pushing in from both directions away from the phenotypic optimum. The stronger the selection, the sharper the fitness gradient. Height exhibits some shallow stabilizing dynamics; the very tall and very short seem to be less fit
Examining the equation, and knowing the parameters, some relations which we comprehend intuitively become clear. The larger the denominator, the lower the rate of maximum environmental change which would allow for population persistence, so the higher the probability of extinction. Species with large T, long generation times, are at greater risk. Scenarios where the the environmental sensitivity to selection, B, is much greater than the ability of an organism to track its environment through phenotypic plasticity, b, increase the probability of extinction. Obviously selection takes some time to operate, assuming you have extant genetic variation, so if a sharp shift in environment with radical fitness implications occurs, and the species is unable to track this in any way, population size is going to crash and extinction may become imminent.
On the numerator you see that the more heritable variation you have, the higher ?c. The rate of adaptation is proportional to the amount of heritable phenotypic variation extant within the population, because selection needs variance away from the old optimum toward the new one to shift the population central tendency. In other words if selection doesn’t result in a change in the next generation because the trait isn’t passed on through genes, then that precludes the population being able to shift its median phenotype (though presumably if there is stochastic phenotypic variation from generation to generation it would be able to persist if enough individuals fell within the optimum range). The strength of stabilizing selection and rate of natural increase also weight in favor of population persistence. I presume in the former case it has to do with the efficacy of selection in shifting the phenotypic mean (i.e., it’s like heritability), while in the latter it seems that the ability to bounce back from population crashes would redound to a species’ benefit in scenarios of environmental volatility (selection may cause a great number of deaths per generation until a new equilibrium is attained).
Of course a model like the one above has many approximations so as to approach a level of analytical tractability. They do address some of the interdependencies of the parameters, in particular the trade-offs of phenotypic plasticity. In this equation 1/?2b quantifies the cost of plasticity, r0 represents increase without any cost of plasticity. We’re basically talking about the “Jack-of-all-trades is a master of none” issue here. In a way this crops up when we’re talking of clonal vs. sexual lineages on an evolutionary genetic scale. The general line of thinking is that sexual lineages are at a short-term disadvantage because they’re less optimized for the environment, but when there’s a shift in the environment (or pathogen character) the clonal lineages are at much more risk because they don’t have much variation with which natural selection can work. What was once a sharper phenotypic optimum turns into a narrow and unscalable gully.
Figure 2 illustrates some of the implications of particular parameters in relation to trade-offs:
There’s a lot of explanatory text, as they cite various literature which may, or may not, support their model. Clearly the presentation here is aimed toward goading people into testing their formalism, and to see if it has any utility. I know that those who cherish biodiversity would prefer that we preserve everything (assuming we can actually record all the species), but reality will likely impose upon us particular constraints, and trade-offs. In a cost vs. benefit calculus this sort model may be useful. Which species are likely to be able to track the environmental changes to some extent? Which species are unlikely to be able to track the changes? What are the probabilities? And so forth.
I’ll let the authors conclude:
Our aim was to describe an approach based on evolutionary and demographic mechanisms that can be used to make predictions on population persistence in a changing environment and to highlight the most important variables to measure. While this approach is obviously more costly and time-consuming than niche modelling, its results are also likely to be more useful for specific purposes because it explicitly incorporates the factors that limit population response to environmental change.
The feasibility of such a mechanistic approach has been demonstrated by a few recent studies. Deutsch et al…used thermal tolerance curves to predict the fitness consequence of climate change for many species of terrestrial insects across latitudes, but without explicitly considering phenotypic plasticity or genetic evolution. Kearney et al…combined biophysical models of energy transfers with measures of heritability of egg desiccation to predict how climate change would affect the distribution of the mosquito Aedes aegiptii in Australia. Egg desiccation was treated as a threshold trait, but the possibility of phenotypic plasticity or evolution of the threshold was not considered. These encouraging efforts call for more empirical studies where genetic evolution and phenotypic plasticity are combined with demography to make predictions about population persistence in a changing environment. The simple approach we have outlined is a necessary step towards a more specific and comprehensive understanding of the influence of environmental change on population extinction.
Citation: Chevin L-M, Lande R, & Mace GM (2010). Adaptation, Plasticity, and Extinction in a Changing Environment: Towards a Predictive Theory PLoS Biol : 10.1371/journal.pbio.1000357
Dr. Daniel MacArthur pointed me to this story, Conn. woman alleges genetic discrimination at work:
A Connecticut woman who had a voluntary double mastectomy after genetic testing is alleging her employer eliminated her job after learning she carried a gene implicated in breast cancer.
Pamela Fink, 39, of Fairfield said in discrimination complaints that her bosses at natural gas and electric supplier MXenergy gave her glowing evaluations for years, but targeted, demoted and eventually dismissed her when she told them of the genetic test results.
Her complaints, filed Tuesday with the U.S. Equal Opportunity Commission and Connecticut Commission on Human Rights and Opportunities, are among the first known to be filed nationwide based on the federal Genetic Information Nondiscrimination Act.
What probability do readers put in regards to this being a legitimate complaint? This seems a large firm, so I doubt that group insurance rates would change because of one person (I have heard of this occurring in small businesses where an expensive employee or employee’s family member can effect the rate for everyone else). So if it is legitimate the main issue would have been their fear of future illness, but the woman in question went through a double mastectomy, which I assume would obviate that concern. What am I missing? Are there expectations that she’d be taking medical leave in the future due to follow up operations or treatment?
Update: Brendan Maher has some follow up from Fink’s lawyer.
On Friday at our Harvard Kennedy School event, I'm going to be giving my rather pessimistic take--already laid out in Unscientific America, and only amplified by "ClimateGate" and other events since then--on the science blogosphere. I'll talk about how in comparison with the old media, the Internet fragments and narrows the audience for science information, even as there aren't really any norms for responsible conduct--and thus, misinformation, innuendo, and general nastiness abound. I'm sure, however, that others will have a different view. Perhaps Joe Romm will; he has just joined our roster for the event. Certainly, his blog has been a major success and demonstrates many of the upsides of science blogging. Such debate is all to the good; it's why we're having the event in the first place. Indeed, I myself will point out some clear positives when it comes to blogging about science (I'm sure you can guess many of them). But taken as a whole, are blogs broadening the conversation about science by reaching new audiences, replacing what has been lost in terms of science coverage in the old media, or elevating our general science discourse? I have to say, I'm skeptical. There is no going back from this new world, but ...
Prepared Remarks by Charles Bolden at NASA JSC 28 April 2010
"For my friends in the media - and I think you all know that I mean that in all sincerity - our NASA team cannot be successful in telling our incredible story without your cooperation and assistance. I will always attempt to be responsive to your requests for access, within reason. But you are not a friend of the space program when you misrepresent the statements or actions of our dedicated, loyal workforce for the sake of a headline-winning story. Again, please don't take this as an attempt to blame the messenger for NASA's problems. That is not the case nor my intent. Rather, please realize that this is a major change in trajectory for our Nation's space program, and that such change is bound to be turbulent in the formative stages. I know that this Nation's aerospace enterprise is capable of coming together and moving forward as one."
Keith's note: If NASA management were to stop thinking of the media in terms of "friends" or its implied counterpart (enemies) and focused instead upon being responsive to the media when the agency is legitimately questioning NASA's problems (things NASA would prefer to to talk about), then the adversarial relationship would improve. Thinking in "us vs them" terms, as is evidenced in Bolden's remarks, simply perpetuates the problem.
