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posted by martyb on Friday May 12 2017, @05:47PM   Printer-friendly
from the some-like-it-hot dept.

http://newsroom.unsw.edu.au/news/science-tech/oldest-evidence-life-land-found-348-billion-year-old-australian-rocks

Fossils discovered by UNSW scientists in 3.48 billion year old hot spring deposits in the Pilbara region of Western Australia have pushed back by 580 million years the earliest known existence of microbial life on land. Previously, the world's oldest evidence for microbial life on land came from 2.7- 2.9 billion-year-old deposits in South Africa containing organic matter-rich ancient soils.

"Our exciting findings don't just extend back the record of life living in hot springs by 3 billion years, they indicate that life was inhabiting the land much earlier than previously thought, by up to about 580 million years," says study first author, UNSW PhD candidate, Tara Djokic. "This may have implications for an origin of life in freshwater hot springs on land, rather than the more widely discussed idea that life developed in the ocean and adapted to land later."

Scientists are considering two hypotheses regarding the origin of life. Either that it began in deep sea hydrothermal vents, or alternatively that it began on land in a version of Charles Darwin's "warm little pond". "The discovery of potential biological signatures in these ancient hot springs in Western Australia provides a geological perspective that may lend weight to a land-based origin of life," says Ms Djokic.

Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits (open, DOI: 10.1038/ncomms15263) (DX)

Previously:
3.7 Billion-Year-Old Fossil Found
Oldest Evidence of Life on Earth Found in 3.77-4.28 Billion Year Old Fossils
Researchers Use Genetic Analysis to Determine That Comb Jellies Were the Earliest Animals


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  • (Score: 2) by kaszz on Friday May 12 2017, @06:58PM (9 children)

    by kaszz (4211) on Friday May 12 2017, @06:58PM (#508792) Journal

    Out of curiosity what was the atmospheric pressure 3.48 billion years ago?

    Another observation is that it took roughly less than a 1 billion years for life to establish itself on Earth from it's generation by condensed and gravitated matter.

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  • (Score: 0) by Anonymous Coward on Friday May 12 2017, @08:45PM (1 child)

    by Anonymous Coward on Friday May 12 2017, @08:45PM (#508846)

    Why are you asking us? I've heard you can use thing thing called Bing. no not that... Google! to find things out. If you have a computer, click the button that says IE6 or AOL and you'll be right there.

    • (Score: 2) by kaszz on Saturday May 13 2017, @06:07AM

      by kaszz (4211) on Saturday May 13 2017, @06:07AM (#509030) Journal

      There are a lot of good search services. None seems to support regex however. Regardless they don't have the answer to everything, there are a lot of diagrams and numbers on the composition, ie CO2. But not pressure.

  • (Score: 3, Funny) by khallow on Friday May 12 2017, @08:53PM (6 children)

    by khallow (3766) Subscriber Badge on Friday May 12 2017, @08:53PM (#508848) Journal

    Out of curiosity what was the atmospheric pressure 3.48 billion years ago?

    No one has a good idea. But this paper [acs.org] proposes an interesting idea and has some strong supporting evidence. Namely, that the Earth started with a high CO2 atmosphere of similar mass and pressure to that of Venus today and has drawn down that atmosphere over the past billion years or so via a combination of silicate weathering, fixing of carbon by organic life, and burying of carbon via plate tectonics.

    • (Score: 1) by khallow on Friday May 12 2017, @09:07PM (5 children)

      by khallow (3766) Subscriber Badge on Friday May 12 2017, @09:07PM (#508853) Journal
      And this paper [washington.edu] suggests that pressure at 2.7 billion years ago may have been less than half modern air pressure at sea level. Looks like asking the question of what the atmospheric pressure was in the geological past is a much harder question than at first glance.
      • (Score: 2) by Immerman on Friday May 12 2017, @09:26PM (4 children)

        by Immerman (3985) on Friday May 12 2017, @09:26PM (#508860)

        Exactly how simple does it look at your first glance? I mean, I can see how questions of atmospheric composition might be answered by finding mineral formations that trapped air samples from that time... but pressure? Where would you even begin?

        • (Score: 3, Interesting) by khallow on Friday May 12 2017, @10:02PM (3 children)

          by khallow (3766) Subscriber Badge on Friday May 12 2017, @10:02PM (#508875) Journal

          Exactly how simple does it look at your first glance?

          In the past, it's been assumed to be near constant. Life is kind of sensitive to pressure, particularly multicellular life, which does cover a fair bit of the period. Ignorance sometimes is like that.

          ... but pressure? Where would you even begin?

          The size of fossils of flying animals, fossilized rain drops, and the ratio of chamber sizes (between top and bottom of the flow) in certain basalt flows.

          • (Score: 2) by kaszz on Saturday May 13 2017, @06:09AM (1 child)

            by kaszz (4211) on Saturday May 13 2017, @06:09AM (#509031) Journal

            The ability of atmospheric gases to penetrate rock etc could perhaps give an insight?

            • (Score: 1) by khallow on Saturday May 13 2017, @12:00PM

              by khallow (3766) Subscriber Badge on Saturday May 13 2017, @12:00PM (#509104) Journal
              Ocean chemistry might be a better bet since we have a fairly good record of that and it goes back further than water-based life could exist on Earth.
          • (Score: 2) by Immerman on Saturday May 13 2017, @02:09PM

            by Immerman (3985) on Saturday May 13 2017, @02:09PM (#509151)

            Okay, I could see how with enough theory fossilized rain drop imprints might give some insight - though given the massive range in sizes today there would probably be *huge* error bars. And yeah, I suppose ambient pressure would have an effect on rock chambers, wouldn't it? The greater the ambient pressure, the lower the relative pressure gradient between the top and bottom of the flow. Though... if seems like a lot of other factors, especially the temperature of the flowing rock and ambient environment, would introduce major confounding factors.

            Flying animals though - I could definitely see how they would be immensely informative, if they existed. But we're talking about a time period roughly 2 billion years before it's generally accepted that multicellular life of any kind emerged...