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  • richardmitnick 4:43 pm on March 1, 2017 Permalink | Reply
    Tags: 3.77-billion-year-old fossils stake new claim to oldest evidence of life, , , , , , , , , Stromatolites   

    From Science: “3.77-billion-year-old fossils stake new claim to oldest evidence of life” 

    AAAS
    Science Magazine

    Mar. 1, 2017
    Carolyn Gramling

    1
    These tubelike structures, formed of an iron ore called hematite, may be microfossils of 3.77-billion-year-old life at ancient hydrothermal vents.

    Life on Earth may have originated in the sunless depths of the ocean rather than shallow seas. In a new study, scientists studying 3.77-billion-year-old rocks have found tubelike fossils similar to structures found at hydrothermal vents, which host thriving biological communities. That would make them more than 300 million years older than the most ancient signs of life on Earth—fossilized microbial mats called stromatolites that grew in shallow seas. Other scientists are skeptical about the new claims.

    “The authors offer a convincing set of observations that could signify life,” says Kurt Konhauser, a geomicrobiologist at the University of Alberta in Edmonton, Canada, who was not involved in the study. But “at present, I do not see a way in which we will definitively prove ancient life at 3.8 billion years ago.”

    When life first emerged on Earth has been an enduring and frustrating mystery. The planet is 4.55 billion years old, but thanks to plate tectonics and the constant recycling of Earth’s crust, only a handful of rock outcrops remain that are older than 3 billion years, including 3.7-billion-year-old formations in Greenland’s Isua Greenstone Belt. And these rocks tend to be twisted up and chemically altered by heat and pressure, making it devilishly difficult to detect unequivocal signs of life.

    “It’s a challenge in rocks that have been this messed up,” says Abigail Allwood, a geologist with NASA’s Jet Propulsion Laboratory in Pasadena, California, who was also not involved in the study. “There’s only so much you can do with them.”

    Nevertheless, researchers have searched through these most ancient rocks for structural or chemical relics that may have lingered. Last year, for example, scientists reported identifying odd reddish peaks in 3.7-billion-year-old rocks in Greenland that may be the product of stromatolites, though many doubted that interpretation. The best evidence for these fossilized algal mats comes from 3.4-billion-year-old rocks in Australia, generally thought of as the strongest evidence for early life on Earth.

    But some scientists think ocean life may have begun earlier—and deeper. In the modern ocean, life thrives in and around the vents that form near seafloor spreading ridges or subduction zones—places where Earth’s tectonic plates are pulling apart or grinding together. The vents spew seawater, superheated by magma in the ocean crust and laden with metal minerals such as iron sulfide. As the water cools, the metals settle out, forming towering spires and chimneys. The mysterious ecosystem that inhabits this sunless, harsh environment includes bacteria and giant tube worms that don’t derive energy from photosynthesis. Such hardy communities, scientists have suggested, may not only have thrived on early Earth, but may also be an analog for life on other planets.

    Now, a team led by geochemist Dominic Papineau of University College London and his Ph.D. student Matthew Dodd says it has found clear evidence of such ancient vent life. The clues come from ancient rocks in northern Quebec in Canada that are at least 3.77 billion years old and may be even older than 4 billion years. Dodd examined hair-thin slices of rock from this formation and found intriguing features: tiny tubes composed of an iron oxide called hematite, as well as filaments of hematite that branch out and sometimes terminate into large knobs.

    Filaments and tubes are common features in more recent fossils that are attributed to the activity of iron-oxidizing bacteria at seafloor hydrothermal vents. Papineau was initially skeptical. However, he says, “within a year [Dodd] had found so much compelling evidence that I was convinced.”

    The team also identified carbonate “rosettes,” tiny concentric rings that contain traces of life’s building blocks including carbon, calcium, and phosphorus; and tiny, round granules of graphite, a form of carbon. Such rosettes and granules had been observed previously in rocks of similar age, but whether they are biological in origin is hotly debated. The rosettes can form nonbiologically from a series of chemical reactions, but Papineau says the rosettes in the new study contain a calcium phosphate mineral called apatite, which strongly suggests the presence of microorganisms. The graphite granules may represent part of a complicated chemical chain reaction mediated by the bacteria, he says. Taken together, the structures and their chemistry point to a biological origin near a submarine hydrothermal vent, the team reports online today in Nature. That would make them among the oldest signs of life on Earth—and, depending on the actual age of the rocks, possibly the oldest.

    That doesn’t necessarily mean that life originated in deep waters rather than in shallow seas, Papineau says. “It’s not necessarily mutually exclusive—if we are ready to accept the fact that life diversified very early.” Both the iron-oxidizing bacteria and the photosynthetic cyanobacteria that build stromatolite mats could have evolved from an earlier ancestor, he says.

    But researchers like Konhauser remain skeptical of the paper’s conclusion. For example, he says, the observed hematite tubes and filaments are similar to structures associated with iron-oxidizing bacteria, “but of course that does not mean the [3.77-] billion-year-old structures are cells.” Moreover, he notes, if the tubes were formed by iron-oxidizing bacteria, they would need oxygen, in short supply at this early moment in Earth’s history. It implies that photosynthetic bacteria were already around to produce it. But it’s still unclear how oxygen would get down to the depths of early Earth’s ocean. The cyanobacteria that make stromatolites, on the other hand, make oxygen rather than consume it.

    The new paper makes “a more detailed case than has been presented previously,” Allwood says. Most previous reports of possible signs of life older than about 3.5 billion years have been questioned, she adds—not because life didn’t exist, but because it’s just so difficult to prove the further back in time you go in the rock record. “There’s still quite a bit of room for doubt.”

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  • richardmitnick 9:18 am on January 23, 2017 Permalink | Reply
    Tags: , Complex cells that go back maybe 1 ¾ billion years, Conditions right for complex life may have come and gone in Earth’s distant past, , Selenium, Stromatolites,   

    From U Washington: “Conditions right for complex life may have come and gone in Earth’s distant past” 

    U Washington

    University of Washington

    January 17, 2017
    Peter Kelley

    1
    This is a 1.9-billion-year-old stromatolite — or mound made by microbes that lived in shallow water — called the Gunflint Formation in northern Minnesota. The environment of the oxygen “overshoot” described in research by Michael Kipp, Eva Stüeken and Roger Buick may have included this sort of oxygen-rich setting that is suitable for complex life.Eva Stüeken.

    Conditions suitable to support complex life may have developed in Earth’s oceans — and then faded — more than a billion years before life truly took hold, a new University of Washington-led study has found.

    The findings, based on using the element selenium as a tool to measure oxygen in the distant past, may also benefit the search for signs of life beyond Earth.

    In a paper published Jan. 18 in the Proceedings of the National Academy of Sciences, lead author Michael Kipp, a UW doctoral student in Earth and space sciences, analyzed isotopic ratios of the element selenium in sedimentary rocks to measure the presence of oxygen in Earth’s atmosphere between 2 and 2.4 billion years ago.

    Kipp’s UW coauthors are former Earth and space sciences postdoctoral researcher Eva Stüeken — now a faculty member at the University of St. Andrews in Scotland — and professor Roger Buick, who is also a faculty member with the UW Astrobiology Program. Their other coauthor is Andrey Bekker of the University of California, Riverside, whose original hypothesis this work helps confirm, the researchers said.

    “There is fossil evidence of complex cells that go back maybe 1 ¾ billion years,” said Buick. “But the oldest fossil is not necessarily the oldest one that ever lived – because the chances of getting preserved as a fossil are pretty low.

    “This research shows that there was enough oxygen in the environment to have allowed complex cells to have evolved, and to have become ecologically important, before there was fossil evidence.” He added, “That doesn’t mean that they did — but they could have.”

    Kipp and Stüeken learned this by analyzing selenium traces in pieces of sedimentary shale from the particular time periods using mass spectrometry in the UW Isotope Geochemistry Lab, to discover if selenium had been changed by the presence of oxygen, or oxidized. Oxidized selenium compounds can then get reduced, causing a shift in the isotopic ratios which gets recorded in the rocks. The abundance of selenium also increases in the rocks when lots of oxygen is present.

    Buick said it was previously thought that oxygen on Earth had a history of “none, then some, then a lot. But what it looks like now is, there was a period of a quarter of a billion years or so where oxygen came quite high, and then sunk back down again.”

    The oxygen’s persistence over a long stretch of time is an important factor, Kipp stressed: “Whereas before and after maybe there were transient environments that could have occasionally supported these organisms, to get them to evolve and be a substantial part of the ecosystem, you need oxygen to persist for a long time.”

    Stüeken said such an oxygen increase has been guessed at previously, but it was unclear how widespread it was. This research creates a clearer picture of what this oxygen “overshoot” looked like: “That it was moderately significant in the atmosphere and surface ocean – but not at all in the deep ocean.”

    What caused oxygen levels to soar this way only to crash just as dramatically?

    “That’s the million-dollar question,” Stüeken said. “It’s unknown why it happened, and why it ended.”

    “It is an unprecedented time in Earth’s history,” Buick said. “If you look at the selenium isotope record through time, it’s a unique interval. If you look before and after, everything’s different.”

    The use of selenium — named after the Greek word for moon — as an effective tool to probe oxygen levels in deep time could also be helpful in the search for oxygen — and so perhaps life — beyond Earth, the researchers said.

    Future generations of space-based telescopes, they note, will give astronomers information about the atmospheric composition of distant planets. Some of these could be approximately Earth-sized and potentially have appreciable atmospheric oxygen.

    “The recognition of an interval in Earth’s distant past that may have had near-modern oxygen levels, but far different biological inhabitants, could mean that the remote detection of an oxygen-rich world is not necessarily proof of a complex biosphere,” Kipp said.

    Buick concluded, “This is a new way of measuring oxygen in a planet’s historical past, to see whether complex life could have evolved there and persisted long enough to evolve into intelligent beings.”

    The research was funded by grants from the National Science Foundation, NASA and the NASA Astrobiology Institute and Canada’s Natural Sciences and Engineering Research Council.

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  • richardmitnick 9:41 pm on January 15, 2017 Permalink | Reply
    Tags: , , , , ELSI - Earth-Life Science Institute, EON - ELSI Origins Network, LUCA - the Last Universal Common Ancestor of Life on Earth, , , , Stromatolites   

    From Many Worlds: “Messy Chemistry, Evolving Rocks, and the Origin of Life” 

    NASA NExSS bloc

    NASA NExSS

    Many Worlds

    Many Words icon

    2017-01-15
    Marc Kaufman

    1
    Ribosomes are life’s oldest and most universal assembly of molecules. Today’s ribosome converts genetic information (RNA) into proteins that carry out various functions in an organism. A growing number of scientists are exploring how earliest components of life such as the ribosome came to be. They’re making surprising progress, but the going remains tough. No image credit.

    Noted synthetic life researcher Steven Benner of Foundation for Applied Molecular Evolution is fond of pointing out that gooey tars are the end product of too many experiments in his field. His widely-held view is that the tars, made out of chemicals known to be important in the origin of life, are nonetheless a dead end to be avoided when trying to work out how life began.

    But in the changing world of origins of life research, others are asking whether those messy tars might not be a breeding ground for the origin of life, rather than an obstacle to it.

    One of those is chemist and astrobiologist Irena Mamajanov of the Earth-Life Science Institute (ELSI) in Tokyo. As she recently explained during an institute symposium, scientists know that tar-like substances were present on early Earth, and that she and her colleagues are now aggressively studying their potential role in the prebiotic chemical transformations that ultimately allowed life to emerge out of non-life.

    “We call what we do messy chemistry, and we think it can help shed light on some important processes that make life possible.”

    2
    Irena Mamajanov of the Earth-Life Science Institute (ELSI) in Tokyo was the science lead for a just completed symposium on emerging approaches to the origin of life question.

    It stands to reason that the gunky tar played a role, she said, because tars allow some essential processes to occur: They can concentrate compounds, it can encapsulate them, and they could provide a kind of primitive (messy) scaffolding that could eventually evolve into the essential backbones of a living entity.

    “Scientists in the field have tended to think of the origin of life as a process going from simple to more complex, but we think it may have gone from very complex — messy — to more structured.”

    Mamajanov is part of an unusual group gathered at (ELSI), a relatively new site on the campus of the Tokyo Institute of Technology for origin of life study with a mandate to be interdisciplinary and to think big and outside the box.

    ELSI just completed its fifth annual symposium, and it brought together researchers from a wide range of fields to share their research on what might have led to the emergence of life. And being so interdisciplinary, the ELSI gathering was anything but straight and narrow itself.

    There was talk of the “evolution” of prebiotic compounds; of how the same universal 30 to 50 genes can be found in all living things from bacteria to us; of the possibility that the genomes of currently alive microbes surviving in extreme environments provide a window into the very earliest life; and even that evolutionary biology suggests that life on other Earth-like planets may well have evolved to form rather familiar creatures.

    Except for that last subject, the focus was very much on ways to identify the last universal common ancestor (LUCA), and what about Earth made life possible and what about life changed Earth.

    Scientific interest in the origin of life on Earth (and potentially elsewhere) tends to wax and wane, in large part because the problem is so endlessly complex. It’s one of the biggest questions in science, but some say that it will never be fully answered.

    But there has been a relatively recent upsurge in attention being paid and in funding for origin of life researchers.

    The Japanese government gave $100 million to start and operate ELSI, the Simons Foundation has donated another $100 million for an origins of life institute at Harvard, the Templeton Foundation has made numerous origin of life grants and, as it has for years, the NASA Astrobiology Institute has funded researchers. Some of the findings and theories are most intriguing and represent a break of sorts from the past.

    For some decades now, the origins of life field has been pretty sharply divided. One group holds that life began when metabolism (a small set of reactions able to harness and transform energy ) arose spontaneously; others maintain that it was the ability of a chemical system to replicate itself (the RNA world) that was the turning point. Metabolism First versus the RNA First, plus some lower-profile theories.

    In keeping with its goal of bringing scientists and disciplines together and to avoid as much origin-of-life dogma as possible, Mamajanov sees their “messy chemistry” approach as a third way and a more non-confrontational approach. It’s not a model for how life began per se, but one of many new approaches designed to shed light and collect data about those myriad processes.

    “This division in the field is hurting science because people are not talking to each other ,” she said. “By design we’re not in one camp or another.”

    3
    Loren Williams of Georgia tech

    Another speaker who exemplified that approach was Loren Williams of Georgia Tech, a biochemist whose lab studies the genetic makeup of those universal 30 to 50 ribosomes (a complex molecule made of RNA molecules and proteins that form a factory for protein synthesis in cells.) He was principal investigator for the NASA Astrobiology Institute’s Georgia Tech Center for Ribosome Adaptation and Evolution from 2009-2014.

    His goal is to collect hard data on these most common genes, with the inference that they are the oldest and closest to LUCA.

    “What becomes quickly clear is that the models of the origin of life don’t fit the data,” he said. “What the RNA model predicts, for instance, is totally disconnected from this data. So what happens with this disconnect? The modelers throw away the data. They say it doesn’t relate. Instead, I ignore the models.”

    A primary conclusion of his work is that early molecules — rather like many symbiotic relationships in nature today — need each other to survive. He gave the current day example of the fig wasp, which spends its larval stage in a fig, then serves as a pollinator for the tree, and then survives on the fruit that appears.

    He sees a parallel “mutualism” in the ribosomes he studies. “RNA is made by protein; all protein is made by RNA,” he said. It’s such a powerful concept for him that he wonders if “mutualism” doesn’t define a living system from the non-living.

    4
    These stromatolites, wavelike patterns created by bacteria embedded in sediment, are 3.7 billion years old and may represent the oldest life on the planet. Photo by Allen Nutman

    5
    Stromalites, sedimentary structures produced by microorganisms, today at Shark Bay, Australia. Remarkably, the lifeform has survived through billions of years of radical transformation on Earth, catastrophes and ever-changing ecologies.

    A consistent theme of the conference was that life emerged from the geochemistry present in early Earth. It’s an unavoidable truth that leads down some intriguing pathways.

    As planetary scientist Marc Hirschmann of the University of Minnesota reported at the gathering, the Earth actually has far less carbon, oxygen, nitrogen and other elements essential for life than the sun, than most asteroids, than even intersellar space.

    Since Earth was initially formed with the same galactic chemistry as those other bodies and arenas, Hirschmann said, the story of how the Earth was formed is one of losing substantial amounts of those elements rather than, as is commonly thought, by gaining them.

    The logic of this dynamic raises the question of how much of those elements does a planet have to lose, or can lose, to be considered habitable. And that in turn requires examination of how the Earth lost so much of its primordial inheritance — most likely from the impact that formed the moon, the resulting destruction of the early Earth atmosphere, and the later movement of the elements into the depths of the planet via plate tectonics. It’s all now considered part of the origins story.

    And as argued by Charley Lineweaver, a cosmologist with the Planetary Science Institute and the Australian National University, it has become increasingly difficult to contend that life on other planets is anything but abundant, especially now that we know that virtually all stars have planets orbiting them and that many billions of those planets will be the size of Earth.

    Other planets will have similar geochemical regimes and some will have undergone events that make their distribution of elements favorable for life. And as described by Eric Smith, an expert in complex systems at ELSI and the Santa Fe Institute, the logic of physics says that if life can emerge then it will.

    Any particular planetary life may not evolve beyond single cell lifeforms for a variety of reasons, but it will have emerged. The concept of the “origin of life” has taken on some very new meanings.

    6
    ELSI was created in 2012 after its founders won a World Premier International Research Center Initiative grant from the Japanese government. The WPI grant is awarded to institutes with a research vision to become globally competitive centers that can attract the best scientists from around the world to come work in Japan.

    The nature and aims of ELSI and its companion group the ELSI Origins Network (EON) strike me as part of the story. They break many molds.

    The creators of ELSI, both Japanese and from elsewhere, say that the institute is highly unusual for its welcome of non-Japanese faculty and students. They stay for years or months or even weeks as visitors.

    While ELSI is an government-funded institute with buildings, professors, researchers and a mission (to greatly enhance origin of life study in Japan), EON is a far-flung collection of top international origins scientists of many disciplines. Their home bases are places like Princeton’s Institute for Advanced Study, Harvard, Columbia, Dartmouth, Caltech and the University of Minnesota, among others in the U.S., Europe and Asia. NASA officials also play a supporting, but not financial, role.

    ELSI postdocs and other students live in Tokyo, while the EON fellows spend six months at ELSI and six months at home institutions. All of this is in the pursuit of scientific collaboration, exposing young scientists in one field related to origins to those in another, and generally adding to global knowledge about the sprawling subject of origins of life.

    Jim Cleaves, of ELSI and the Institute for Advanced Study, is the director of EON and an ambassador of sorts for its unusual mission. He, and others at the ELSI symposium, are eager to share their science and want young scientists interested in the origins of life to know there are many opportunities with ELSI and EON for research, study and visitorships on the Tokyo campus.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 7:40 pm on August 31, 2016 Permalink | Reply
    Tags: , , , Scientists find 3.7 billion-year-old fossil - oldest yet - in Greenland, Stromatolites,   

    From UNSW via phys.org: “Scientists find 3.7 billion-year-old fossil, oldest yet” 

    U NSW bloc

    University of New South Wales

    phys.org

    phys.org

    August 31, 2016
    Seth Borenstein, phys.org

    1
    In this photo provided by Laure Gauthiez, taken in July 2012, a field team examine rocks in Greenland. Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth’s skies were orange and its oceans green. In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday, Aug. 31, 2016 journal Nature. (Laure Gauthiez/The Australian National University via AP)

    Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth’s skies were orange and its oceans green.

    In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday’s journal Nature .

    The discovery shows life may have formed quicker and easier than once thought, about half a billion years after Earth formed . And that may also give hope for life forming elsewhere, such as Mars, said study co-author Martin VanKranendonk of the University of New South Wales and director of the Australian Center for Astrobiology.

    “It gives us an idea how our planet evolved and how life gained a foothold,” VanKranendonk said.

    Scientists had thought it would take at least half a billion years for life to form after the molten Earth started to cool a bit, but this shows it could have happened quicker, he said. That’s because the newly found fossil is far too complex to have developed soon after the planet’s first life forms, he said.

    In an outcrop of rocks that used to be covered with ice and snow which melted after an exceptionally warm spring, the Australian team found stromatolites, which are intricately layered microscopic layered structures that are often produced by a community of microbes. The stromatolites were about .4 to 1.6 inches high (1 to 4 centimeters).

    It “is like the house left behind made by the microbes,” VanKranendonk said.

    Scientists used the layers of ash from volcanoes and tiny zircon with uranium and lead to date this back 3.7 billion years ago, using a standard dating method, VanKranendonk said.

    1
    In this photo provided by Allen Nutman, a rock with the stromatolites, tiny layered structures from 3.7 billion years ago that are remnants from a community of microbes that used to be live there. Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth’s skies were orange and its oceans green. In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday, Aug. 31, 2016 journal Nature. (Allen Nutman/University of Wollongong via AP)

    3
    Stromatolites are found in similar environments today, such as Shark Bay, Western Australia, https://uwaterloo.ca/peter-russell-rock-garden/rock-garden/rock-groups/proterozoic-rocks/stromatolite-marble

    “It would have been a very different world. It would have had black continents, a green ocean with orange skies,” he said. The land was likely black because the cooling lava had no plants, while large amounts of iron made the oceans green. Because the atmosphere had very little oxygen and oxygen is what makes the sky blue, its predominant color would have been orange, he said.

    The dating seems about right, said Abigail Allwood , a NASA astrobiologist who found the previous oldest fossil, from 3.48 billion years ago, in Australia. But Allwood said she is not completely convinced that what VanKranendonk’s team found once was alive. She said the evidence wasn’t conclusive enough that it was life and not a geologic quirk.

    “It would be nice to have more evidence, but in these rocks that’s a lot to ask,” Allwood said in an email.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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    Welcome to UNSW Australia (The University of New South Wales), one of Australia’s leading research and teaching universities. At UNSW, we take pride in the broad range and high quality of our teaching programs. Our teaching gains strength and currency from our research activities, strong industry links and our international nature; UNSW has a strong regional and global engagement.

    In developing new ideas and promoting lasting knowledge we are creating an academic environment where outstanding students and scholars from around the world can be inspired to excel in their programs of study and research. Partnerships with both local and global communities allow UNSW to share knowledge, debate and research outcomes. UNSW’s public events include concert performances, open days and public forums on issues such as the environment, healthcare and global politics. We encourage you to explore the UNSW website so you can find out more about what we do.

     
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