Johnald's Fantastical Daily Link Splurge |
- Massive Star Blows Fancy Hourglass Nebula
- Searching for Network Laws in Slime
- Mud Volcano Was Man-Made, New Evidence Confirms
- Antibiotics Breed Superbugs Faster Than Expected
- New 3-D Map of Interstellar Gas Around the Sun
- Martian Dune Mystery Solved by Bouncing Sand Grains
- Saturn’s Most Habitable Moon Offers Ice, Water, Killer Views
- Early Galaxies Formed Stars Fast Because They Had More Gas
- First Ancient-Human Genome Sequence Answers Anthropological Riddle
- New Telescope Captures Dazzling Image of Orion Nebula
| Massive Star Blows Fancy Hourglass Nebula Posted: 12 Feb 2010 03:45 PM PST
The beautiful hourglass-shaped nebula Sharpless 2-106 shines with brilliant colors in this new image from the Gemini North telescope.
The new data from Gemini North is considerably better than previous images, such as the one at the right. The nebula is part of a catalog published by Stewart Sharpless in 1959. It's about 2 light-years long and half a light-year wide. It's located about 2,000 light years away in the direction of the Constellation Cygnus. The image was captured using four narrow-band filters that have been tuned to see hydrogen as well as ionized helium, sulfur and oxygen. When combined in the top composite, helium is violent, sulfur blue, oxygen green and hydrogen red. Images: 1. Gemini Observatory/AURA See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and green tech history research site; Wired Science on Twitter and Facebook. | |||||||||||||
| Searching for Network Laws in Slime Posted: 12 Feb 2010 10:59 AM PST
Of all science's model organisms, none isas weird as Dictyostelium discoideum, a single-celled amoeba better known as slime mold. When they run out of food, millions coalesce into a single, slug-like creature that wanders in search of nutrients, then forms a mushroom-like stalk, scatters as spores and starts the cycle again. In the rules governing the behavior of these creatures, researchers hope to find analogues for baffling biological mysteries, from the specialization of cells to how animals become altruistic. "What I look for is principles that work on different scales," said Princeton University biologist Ted Cox, who in an upcoming Nucleic Acids Research paper describes how cellular proteins find their DNA targets, a process he links to the slime mold's foraging patterns. "The theoretical underpinning is exactly the same."
Research on Dictyostelium took off in the 1950s, when work by Princeton biologist John Bonner led to the discovery of a chemical used by slime mold cells to signal, triggering their group-forming behavior. At the time, scientists assumed that a few specialized cells controlled the process. But a couple decades later, inspired by famed mathematician Alan Turing's work on how simple rules produced complex structures, researchers showed that slime complexity resulted from the linked interactions of its cells, not some centralized regulator.
In a paper published Monday in the Proceedings of the National Academy of Sciences, researchers showed how Physarum is even better at maintaining a balanced diet than humans. In January, researchers described how it found ultra-efficient routes between food arrayed like Japanese cities. (The same trick has also been performed with English roadways.) Researchers have also found that Physarum possesses memory, and think its computational powers can be harnessed in biological computer form. Said Toshiyuki Nagaki, the Hokkaido University scientist who ran Physarum around a model Tokyo, it's time "to reconsider our stupid opinion that single celled organisms are stupid." Their research stirred an ongoing scientific fascination with emergent properties and complexities. Since then, however, Dictyostelium has been overshadowed by Physarum polycephalum, another amoeba that exhibits amazing networking properties and is also known as a slime mold, though it's no closer to the other slime mold than a horse is to a frog. (See sidebar.) To the chagrin of Dictyostelium researchers, the two creatures are sometimes confused with each other. But though the spotlight has moved, Dictyostelium research continues. Most of it has shifted from big-picture work to fine-grained focus. Dictyostelium's genome was sequenced five years ago, and information about its genetic and molecular mechanisms has steadily accumulated. From the application of modern mathematical modeling techniques to these realms of node-by-now measurement, the rules of networks may finally emerge. "Fifty or 60 years ago, ecology was a fantastic collection of facts about organisms. Then along came Robert Macarthur, who used very simple equations to suggest how all this diversity might have occurred," said Bonner, whose book The Social Amoebae was publishedin November. "That opened up a whole new way of thinking about the outside world. And I think that is going to happen with slime molds." According to Cox, the same dynamics governing slime mold signaling likely explain how calcium levels are synchronized — or go haywire — during the beating of a heart, or during embryonic development. The same goes for fluxes of mood-regulating neurotransmitters. "It's a unifying theory of excitable systems," said Cox, who also noted that vortex patterns mapped in aggregating Dictyostelium cells are replicated in the spread of pathogens. Indeed, the slime mold is a useful modelforstudying the transmission dynamics of many diseases, from cholera to tuberculosis. Cox's upcoming paper is the latest in a series of papers on how gene-activating proteins move from one section of DNA to another. Such coordination can be visualized on a larger scale as a pinhead floating in a large room, and landing randomly on a pin. For all practical purposes, it should be impossible, but Cox sees a hint to an answer in how the slime mold "slug" searches for food. "It's Einstein's diffusion equations, in three dimensions," he said. Before the slug searches for food, it has to form. Those dynamics are the focus of Rice University evolutionary biologist Joan Strassman. As described most recently in an October Nature paper, Strassman's work shows how gene mutations that allow individual amoebae to cheat inevitably cause damage to other, essential cell systems. Called "positive pleiotropy," it's a built-in system for ensuring altruistic cooperation, a phenomenon that fascinates biologists. "The microorganisms that help and hurt us are all talking to each other. There are social interactions going on in the bugs in our skin," said Strassman. "This can tell us things about how microbes interact." For a "so-called simple organism," said North Carolina State University biologist Larry Blanton, "it's doing a lot of sophisticated things of relevance to higher organisms." Images: 1) At left, the life cycle of Dictyostelium/Larry Blanton. At right, a spiraling pattern of chemical signaling/Marcus Hauser. 2) Physarum spreading across England, from Andy Adamatzky's "Road planning with slime mould: If Physarum built motorways it would route M6/M74 through Newcastle." See Also:
Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points. | |||||||||||||
| Mud Volcano Was Man-Made, New Evidence Confirms Posted: 11 Feb 2010 04:44 PM PST
A new analysis shows that a deadly mud volcano in Indonesia may not have been a natural disaster after all. The research lends weight to the controversial theory that the volcano wascaused by humans. Villagers near Sidoarjo noticed a mud volcano beginning to erupt at 5 a.m. local time May 29, 2006. It was about 500 feet from a local gas-exploration well. Every day since then, the Lusi mud volcano has pumped out 100,000 tons of mud, or enough to fill 60 Olympic-size swimming pools. It has now covered an area of almost3 square miles to a depth of 65 feet. Thirty thousand people have been displaced, and scientific evidence is mounting that the company drilling the well caused the volcano. "The disaster was caused by pulling the drill string and drill bit out of the hole while the hole was unstable," said Richard Davies, director of the Durham Energy Institute and co-author of a new paper in the journal Marine and Petroleum Geology, in a press release. "This triggered a very large 'kick' in the well, where there is a large influx of water and gas from surrounding rock formations that could not be controlled."
Mud volcanoes can form in two different ways. New fractures in rock that caps mud deposits can open, allowing the mud to rise to the surface if it's under pressure.Or, an earthquake can liquefy mud that then travels through pre-existing cracks to the surface. Davies argues that the "kick" fractured the rock in the area, opening up new pathways for pressurized mud to come flowing up to the surface. Davies' team'sresearch uncovered new evidence from a drilling log that the drilling company, Lapindo Brantas, pumped drilling mud down their well to try to stop the mud volcano. "This was partially successful, and the eruption of the mud volcano slowed down," Davies said. "The fact that the eruption slowed provides the first conclusive evidence that the bore hole was connected to the volcano at the time of eruption." The new paper came in response to a paper published by the company's lead driller in the same journal. Lapindo Brantas has long maintained that drilling did not cause the eruption. Instead, the company claims an earthquake that occurred two days before and about 175 miles away did the damage. Obviously, there are financial ramifications if the drilling company is found liable for the disaster. The problem with the earthquake hypothesis is the stress changes caused by the quake would have been relatively small, too small to cause the volcano, said Davies' co-author, University of California at Berkeley geologist Michael Manga. "There is 1,000 times not enough energy to cause the eruption," Manga said. He was drawn into the controversy when the drilling company cited one of his paperson how earthquakes can cause mud volcanoes and have on 32 occasions. But Manga noted that based on all the historical examples that scientists have, what the company claimed happened was impossible. "So I wrote a one-page paper [in 2007] saying it could not possibly have caused the mud volcano," he said. Other scientists came to similar conclusions, although some doubts remained. An even stronger piece of evidencethat the earthquake could not have created the mud volcano, Manga said, is that in the years before the quake, there were "bigger and closer earthquakes that did not cause an eruption." In fact, the stress changes associated with the tides are larger than the stresses caused by the earthquake that happened to strike two days before the mud volcano eruption began. Still, the editor of the journal in which both the company's paper and the Manga-Davies rebuttal was published said that it was possible that the same data could be subject to multiple interpretations. "In geology, sometimes it's not about being right or wrong, it's about being reasonable or unreasonable," said editor Octavian Catuneanu, geologist at the University of Alberta. "The funny thing is that sometimes datasets can be interpreted by different people in different ways, and this leads to arguments and controversies." Still, there is a large financial incentive for Lapindo Barantas' scientists to find that their company was not responsible. "The drilling company cannot say anything different, right?" Manga said. But Catuneanu said that no matter who the scientists were working for, they still had to meet the scientific standards of the journal. "I guess there would be some bias there, but as a journal editor, what I need to make sure is that the authors of an article stick to the science," he said. "If they want to have something publishable, they have to bring data and discuss it in a scientific manner." Lapindo Barantas could not be reached for comment. Images: 1. AP Photo/Trisnadi See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and green tech history research site; Wired Science on Twitter and Facebook. | |||||||||||||
| Antibiotics Breed Superbugs Faster Than Expected Posted: 11 Feb 2010 01:03 PM PST
A newly discovered mechanism of antibiotic resistance helps explain how bacteria have so quickly undermined medicine's front-line defenses, turning miracle drugs into duds in just a few decades. Scientists have long known that exposing bacteria to the right antibiotics will kill most of them, but leave a few mutants that happen to resist the drug better than the rest. These mutants go on to multiply, and eventually the whole strain evolves resistance. Now a new study paints a more complicated picture of antibiotic resistance. Bacteria don't just develop resistance to one drug at a time, but to many — and at accelerated rates. That's because antibiotics boost bacterial production of free-radical oxygen molecules that damage bacterial DNA. Repairs to the DNA cause widespread mutations, giving bacteria more chances to randomly acquire drug-resistant traits. "You have a wide range of mutations being introduced across the genome. Some afford resistance to that antibiotic. Some afford resistance to other antibiotics," said James Collins, a Boston University biomedical engineer who described the mechanism in a paper publishedFeb. 11in Molecular Cell. "It would happen anyways, but this process is accelerating it."
Drug resistance is a serious public health concern. According to the federal Centers for Disease Control and Prevention, 70 percent of 1.7 million infections acquired in hospitals every year are resistant to at least one drug. Those infections annually kill 99,000 Americans — more than double the number that die in car crashes. Drugs that once destroyed almost any bacteria now kill only a few, or don't work at all. In the case of some drugs, like Cipro, the decline is dramatic: Where in 1999 it worked against 95 percent of E. coli, it treated only 60 percent by 2006. Against lung infection-causing Acinobacter, its effectiveness fell by 70 percent in just four years. Though drug resistance is ultimately inevitable, conventional wisdom holds that antibiotics consumed at suboptimum doses hasten the process. Bugs that would have succumbed to a larger dose live to multiply, pushing the strain as a whole closer to resistance. That happens when a prescription goes unfinished, or when antibiotics used on farms enter food and water at low levels. The conventional wisdom isn't wrong, but the new findings suggest that drugs push bacteria towards resistance even more rapidly, and in more ways, than was thought. "It's a really important paper. It underscores that we don't fully know how antibiotic resistance is engendered," said Harvard University molecular biologist Deborah Hung. "If you treat with low concentrations of antibiotic, the bugs respond by increasing their mutation rates." In earlier research, Collins' team showed that antibiotics don't only kill bacteria as expected –by corroding cell walls, messing with DNA and blocking proteins — but by triggering the release of free-radical oxygen molecules. Thanks to an extra electron, the free radicalsbind easily and corrosively with other molecules, and prove as lethal as the drugs themselves. For the latest study,the researchers testedwhether free radicals might also affect drug resistance by usingsublethal doses of five common antibiotics on Staphylococcus aureus, the annual cause of 500,000 infections in the United States, and two strains of E. coli, including one taken from a patient. The free radicals caused DNA damage that didn't kill all the bacteria.The bacteria'sself-repair processes then introduced mutations to genes that provided resistance to many drugs, not just those being administered. Drugs might be foundthat couldalter bacterial DNA repair systems, but that prospect is extremely speculative, said Collins. Hung said more research is needed to show how different bacteria respond. Mutation rates might vary between strains. It's also possible that free-radical damage also accelerates horizontal gene transfer, in which bacteria swap genes without reproducing. If so, resistance could develop faster and spread more rapidly. "The clinical significance is not clear yet, but it certainly should make us pause and think about the way we use antibiotics," said Hung. In recent years, public health experts have recommended that doctors use antibiotics only when necessary, and that patients complete every prescription. They've also called for dramatic cuts in the agricultural use of antibiotics. Of the 35 million pounds of antibiotics consumed annually in the United States, 80 percent goes to farm animals. Much of it is used to treat diseases spread by industrial husbandry practices, or simply to accelerate growth. As a result, farms have become giant petri dishes for superbugs, especially multidrug-resistant Staphylococcus aureus, or MRSA, which kills 20,000 Americans every year –more than AIDS. Alarming cases of farm-based MRSA and other diseases led to a proposed Congressional law restricting the use of agricultural antibiotics. That bill, supported by the American Medical Association and American Public Health Association, is opposed by farm lobbyists and remains stuck in committee. "We need to look carefully at situations where antibiotics are used in agriculture and water supplies," said Collins. "The benefits may not outweigh the potential harm we're doing by creating stronger, more problematic microbes." Image: Samantha Celera/Flickr See Also:
Citation: "Sublethal Antibiotic Treatment Leads to Multidrug Resistance via Radical-Induced Mutagenesis." By Michael A. Kohanski, Mark A. DePristo, and James J. Collins. Molecular Cell, Vol. 37 No. 3, February 11, 2009. "The Fast Track to Multidrug Resistance." By Benjamin B. Kaufmann and Deborah T. Hung. Molecular Cell, Vol. 37 No. 3, February 11, 2009. Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points. | |||||||||||||
| New 3-D Map of Interstellar Gas Around the Sun Posted: 11 Feb 2010 11:11 AM PST
Space is a pretty empty place. But it's not completely empty, as a new map of the interstellar space in the 1,000 light-years around the sun shows. Using the light from 1,857 stars, a team of French and American astronomers were able to measure the density of the gas surrounding our sun by examining fine differences in the starlight. They confirmed the presence of the Local Cavity, represented by the white area above, which scientists think was swept of gas by an old supernova explosion. "Nobody knows for sure, but the consensus of opinion is that there was a giant supernova that went off about 5 or 10 million years ago, and the big explosion cleared everything out of the way and left a big hole in the interstellar medium," said astronomer Barry Welsh of the University of California at Berkeley. The Local Cavity has a radius of about 260 light-years. The area is so empty that if you were to fly along scooping up the hydrogen atoms in the interstellar medium between our solar system and the edge of the cavity, you'd only have collected enough to fill half a coffee cup with them, Welsh said. The Local Cavity is surrounded by a wall of relatively denser gas. But the wall isn't impenetrable. It'sriddled with "interstellar tunnels" that lead from one pocket of less dense gas to another. The work builds on a 2003 map and was published in the journal Astronomy and Astrophysics. It incorporates more than twice the data of the previous map. By mapping this gas, Welsh said we were filling in major blanks in our knowledge about the galaxy. He said that our previous maps of our local area just had the stars, but not the gas, which was like "a map of the USA that just has the cities." Citation: "New 3D gas density maps of NaI and CaII interstellar absorption within 300 pc," by B. Y. Welsh, R. Lallement, J.-L. Vergely, and S. Raimond. Astronomy and Astrophysics, 2010, vol. 510, A54 (February 9, 2010). See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and green tech history research site; Wired Science on Twitter and Facebook. | |||||||||||||
| Martian Dune Mystery Solved by Bouncing Sand Grains Posted: 11 Feb 2010 12:15 AM PST
Once Martian sand grains hop, they don't stop.
Mars' sandy surface has clearly been shaped by wind. Its characteristic dunes and ripples are the kind formed by sand particles taking short wind-borne hops, a process called saltation.
But atmospheric simulations and landers' direct measurements of wind speed have found that the Martian wind hardly ever blows hard enough to kick sand grains off the ground in the first place. The new paper, to appear in an upcoming Physical Review Letters, suggests a solution to this paradox: a kind of billiard-ball effect in which one sand particle knocks the next one into motion. "It's much easier to keep this process going than it is to start it in the first place," says study author Jasper Kok, an atmospheric physicist at the National Center for Atmospheric Research in Boulder, Colo., who did most of this research while at the University of Michigan in Ann Arbor. "It's like when you ride a bike: It costs a lot of exertion to get it going, but once you're going it's easier to keep going."
"That's hard to study in a wind tunnel," notes planetary scientist Robert Sullivan of Cornell University. The study "goes numerically where we have a hard time going with wind tunnel experiments," he says. The way sand grains knock each other around turns out to make all the difference, Kok says. Because Martian gravity and air density are so much lower than Earth's, a small kick from the wind sends sand particles on Mars flying much higher, up to a meter off the ground. "It's like playing golf on the moon," Kok says. Particles get caught in stronger winds as they rise, causing them to pick up speed and ultimately slam into the ground, where they kick up more particles and start the cycle over. "This splashing process is really efficient," Kok says. "It can keep saltation, or sand blowing, going on Mars at relatively low wind speeds." These jumping sand grains can create ripples over time even without high sustained winds, he says. The finding could help solve other puzzles in the Martian landscape. Earlier models predicted that crescent-shaped sand dunes called barchan dunes should grow to at least 500 meters long — but many are only 100 meters. And the Mars rover Opportunity has found sand ripples made up of particles only 100 micrometers in diameter, so small that scientists had expected them to stay aloft once kicked up. The new model could explain both riddles by showing that splashing can keep particles moving at low wind speeds. Slow-moving sand grains don't travel far and therefore make short dunes, but even tiny particles can get pushed into ripples, Kok says. "This study is very welcome, very informative," Sullivan says. "The results go a long way toward explaining several mysteries."
Images: Martian dunes imaged by HiRISE 1) Barchan dunes. 2) Barchan dunes. 3) Megaripples. Credit: NASA/JPL/University of Arizona. See Also: | |||||||||||||
| Saturn’s Most Habitable Moon Offers Ice, Water, Killer Views Posted: 10 Feb 2010 04:30 PM PST << previous image | next image >> 
Enceladus has to be one of the most intriguing objects in the solar system. It's definitely our favorite of Saturn's 62 moons here at Wired Science, and it's among the most likely places to find the necessary ingredients for extraterrestrial life in the solar system. Enceladus actively spews jets of material from its south pole, forming one of Saturn's majestic rings. New evidence from the jets suggesting that there is a liquid ocean beneath the moon's icy crust was published just this week in the journal Icarus. Data from NASA's Cassini spacecraft, which dove through the jets in 2008, showed the plumes contain negatively charged ions, which have only been found on Earth, another Saturnian moon — Titan — and comets. On Earth, negatively charged ions are found where water is moving, such as in a waterfall or a crashing wave. The discovery of the ions in Enceladus' jets is the best evidence yet of liquid water. On top of being a possible haven for life, Enceladus is beautiful. Its icy crust is riven with cracks and folds that somehow look both familiar and alien at the same time. Older surfaces have impact craters. The four huge, linear depressions at its south pole known as the tiger stripes are probably less than 1,000 years old and warmer than the rest of the crust, evidence that Enceladus is actively forming ice. Though it is just over 300 miles in diameter, a tenth the size of Titan, tiny Enceladus has won us over. With Cassini's new life extension into 2017, and 11 more planned flybys of Enceladus, we can expect more awesome images and enlightening data. Here we have collected some of the best images of Enceladus that Cassini has collected since it began exploring Saturn in 2004. Image: NASA/JPL/CICLOPS | |||||||||||||
| Early Galaxies Formed Stars Fast Because They Had More Gas Posted: 10 Feb 2010 10:41 AM PST
The mystery of why galaxiesformed early in the history of the universe give birth to more stars than modern ones has been solved. An abundance of dense, cold gas fueled rapid star formation in these early galaxies, according to a new study. Astronomers collected signals from 19 different 8- to 10-billion-year old galaxies scattered across the northern sky. These early-universe stellar nurseries had muchmore interstellar gas — dense, hydrogen-rich clouds at a chilly minus 441 to minus 414 degrees Fahrenheit — than their modern counterparts. "This is really pioneering work," said astrophysicist Kai Noeske of the Harvard Smithsonian Center for Astrophysics."It unambiguously confirms that these galaxies really are more gas-rich, so the reason they made more stars back in the day is that they had more fuel to burn."
Scientists study distant galaxies because the light they sent out billions of years ago is only now reaching us, and can therefore tell us about conditions early in the universe's 13.7-billion-year history. No one knew why stars form more than 10 to 100 times more often in distant, massive galaxies than they do in local galaxies of the same mass, said astronomer Linda Tacconi of theMax Planck Institute for Extraterrestrial Physics in Germany, lead author of the Feb. 10 Nature study. Some scientists had guessed thatthese early galaxies contained more cold interstellar gas, which fueled the frenetic birth of stars. Others argued that these ancient galaxies had the same amount of gas as the Milky Way, but that suns formed in short, furious starbursts as these galaxies collided, Noeske said. Determining which theory was right was difficult. The cold, dense gas clouds emit such faint, low-energy light that even the most sensitive instruments can barely detect them. Just a few years ago, Tacconi's team searched for signals from these galaxies, but failed, she said.
Thegroup was finally able to answer the question byadding more-sensitive detectors to the IRAM Plateaude Bure Interferometer, an array of millimeter-wavelength radio telescopes located at 7,381 feet in the French Alps. Ultimately, the team wanted to know how much hydrogen filled these early galaxies,becauseit is by far the most abundant element in the universe and in interstellar gas clouds. But hydrogen emissions from these distant objects are simply too hard to detect, Tacconi said. Instead, they measured the light emitted from carbon monoxide molecules. As these molecules rotate, they shift from one energy state to another. As they shift, "they emit photons, and that radiation is what we see as an emission line at a specific wavelength," Tacconi said. The amount of light emitted from these spinning molecules revealed the fraction of each galaxy made up of carbon monoxide. Carbon monoxide and hydrogen are found in almost the same ratio in many parts of the universe. So, they used this ratio to extrapolate the amount of hydrogen present in these early galaxies. A 10-billion-year-old galaxy was made of about 44 percent cold interstellar gas by mass, while an 8-billion-year-old one was about 34 percent. This is three to 10 times more hydrogen than today's giant galaxies. The study also showed the old galaxies drew in fuel from their surrounding environment in order to keep up the frantic pace of star formation, Noeske said. Future researchshould look at a larger number of galaxies and find a way to measure smaller galaxies, said astronomer Dawn Erb of the University of California, Santa Barbara, who was not involved in the study. "This is just the tail end of the population of the normal galaxies, just the biggest and most massive ones," she said. "We just can't see the normal ones, because they're too faint." To do that, the team will need even-more-sensitive equipment, whichthey will get when the ALMA observatory in Chile comes online in 2012. "That's going to be the next big step,"Erb said. Images: See Also:
Citation:L. J. Tacconi, R. Genzel, R. Neri, P. Cox, M. C. Cooper, K. Shapiro, A. Bolatto, N. Bouché , F. Bournaud,A. Burkert, F. Combes, J. Comerford, M. Davis, N. M. Förster Schreiber, S. Garcia-Burillo, J. Gracia-Carpio, D. Lutz, T. Naab, A. Omont, A. Shapley, A. Sternberg, B. Weine. "High molecular gas fractions in normal massive star-forming galaxies in the young Universe" Nature Vol 463, 11 Feb. 2010. | |||||||||||||
| First Ancient-Human Genome Sequence Answers Anthropological Riddle Posted: 10 Feb 2010 10:35 AM PST
Meet Inuk, a 4,000-year-old man known from a tuft of hair found in Greenland permafrost. In those frozen strands, enough DNA was preserved to sequence the first ancient-human genome and confirm an unexpected ancient migration from Siberia to the New World, plus a few of Inuk's own traits. Along with brown eyes, brown skin and facial hair, he had "a tendency to baldness," said Eske Willerslev, a Niels Bohr Institute evolutionary geneticist who led the analysis, published Monday in Nature. "But because we found quite a lot of hair from this guy, we presume that he died young." The remains of Inuk — which translates to "person" or "human being" in the Inuit language family — were found in Qeqertasussuk, an archaeological site in southwest Greenland. A few bone fragments and hair tufts found at the site are the only biological remnants of the Saqqaq, the earliest known inhabitants of the North American Arctic.
Controversy exists over the Saqqaq's origins. Some anthropologists think they were descended from temperate North Americans who wandered north, or from early ancestors of modern Inuit who left no archaeological trace. But the analysis that revealed Inuk's eye color and impending baldness also returned genetic patterns most closely related to those now found in indigenous inhabitants of eastern Siberia. The Saqqaq appear to have originated there. The findings support the implications of a mitochondrial DNA analysis of the hair published by Willerslev's team in Science in 2008. That study also showed patterns of Siberian origin, and a clear biological break between the Dorset culture (the next-oldest Paleo-Eskimo group) and the ancestors of modern Inuit people. Whether the Saqqaq influenced their cultures is not known, said Willerslev. Inuk's genome is the oldest yet reconstructed by scientists. It may be difficult to perform such decipherings on remains found in warmer climes, which degrade faster. But that remains to be tested. "Such studies have the potential to reconstruct not only our genetic and geographical origins, but also what our ancestors looked like," wrote Griffith University molecular biologists David Lambert and Leon Huynen in an accompanying commentary in Nature. Images See Also:
Citations "Face of the past reconstructed." By David M. Lambert and Leon Huynen. Nature, Vol. 463 No. 7282, Feb. 11, 2010. Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points. | |||||||||||||
| New Telescope Captures Dazzling Image of Orion Nebula Posted: 10 Feb 2010 03:00 AM PST
You've undoubtedly seen the smudge of the Orion Nebula hanging just below his belt thousands of times, but the most beautiful image yet of the celestial body was just released Wednesday.
The European Southern Observatory's new VISTA telescope's enormous field of view allows it to image the entire nebula at once. It's been designed to capture near-infrared light. The longer wavelengths of light in that part of the spectrum allow rays to pass through dusty space without being scattering. The Orion Nebula is located about 1,350 light-years from Earth. The cloud of gas and dust is a nursery for young stars. The red blobs in the features near the center of the image are young, growing stars that are hidden by dust in visible light. VISTA was just placed into service late last year, so we can expect many more beautiful near-infrared images as it conducts its survey of the sky. There are detailed close-up shots below, too.
Image: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit. The 341 MB XXXL version. See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and green tech history research site; Wired Science on Twitter and Facebook. |
Giant star S106IR lies near the waist of the hourglass. Astronomers estimate the star could be up to 15 times more massive than our sun. The winds the star sends ripping through space appear to have generated the nebula's distinctive shape. Scientists believe that as material accretes in a disk around the hot star, perpendicular outflow jets send gas and dust streaming out at speeds of up to 125 miles per second.
Kok modified a numerical model, previously applied to geological processes on Earth, to include Martian gravity and atmospheric conditions. Unlike in other models, Kok simulated a process called splashing, in which a flying sand particle knocks at least one new grain into the air as it smacks into the ground.
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