[HN Gopher] The complicated history of how the Earth's atmospher...
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       The complicated history of how the Earth's atmosphere became
       breathable
        
       Author : Brajeshwar
       Score  : 53 points
       Date   : 2023-05-15 14:43 UTC (2 days ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | pfdietz wrote:
       | It's not clear why the Earth's oxygen has been somewhat stable
       | since the Precambrian. If you kill all plants, oxygen goes away
       | (reacting with reduced materials exposed by erosion and released
       | in volcanism) in just a few million years. It could be an
       | observer selection effect: if it had ever dropped too low in that
       | time, we wouldn't be here now.
        
       | Maursault wrote:
       | > Life began in that alien environment, and at some point between
       | 3.2 and 2.8 billion years ago, cyanobacteria began to use
       | sunlight to split hydrogen from water, discarding oxygen as
       | waste.
       | 
       | David Attenborough brilliantly explains the beginning of life and
       | the role of cyanobacteria in the first episode of Life on Earth
       | (1979), "The Infinite Variety,"[1] (in less than 20 minutes;
       | doesn't need to be that long, but I wanted to catch him riding
       | the mule, sooooo... strap in and enjoy).
       | 
       | [0] https://www.dailymotion.com/video/x2i43qc?start=673
        
       | yarg wrote:
       | The air was never unbreathable in any meaningful sense - it was
       | altered in a way that provided an abundant new resource that
       | permitted the evolution of new forms of life.
        
         | chasil wrote:
         | The "oxygen catastrophe" made the air toxic in ways that life
         | could not evolve to cope with at that time.
         | 
         | The wiki goes on to speculate that eukaryotes were required to
         | solve this problem, which is an enormous amount of time for
         | such toxicity.
         | 
         | https://en.wikipedia.org/wiki/Great_Oxidation_Event
         | 
         | During the cretaceous, oxygen increased so substantially that
         | it would be obversely toxic to modern life, too much instead of
         | too little.
        
           | namaria wrote:
           | Life doesn't evolve to cope with anything. Life evolves as it
           | adds variety and some of it gets cut down by the environment.
           | Narratives implying teleology are misleading and wrong.
        
         | [deleted]
        
       | beders wrote:
       | It's a terrible title and a terrible article altogether.
       | 
       | > Biology, geology, and chemistry all worked together to make the
       | present atmosphere.
       | 
       | No, no one "worked together". And Earth never was an "Alien
       | planet".
       | 
       | Life evolved alongside any challenges that a changing planet
       | posed to it. Including changes induced by organisms. Life still
       | is evolving today and hopefully will continue to do so.
       | 
       | Also titles like this imply that the evolution of our planet and
       | life is somehow guided or is directed to support humans. Or that
       | humans are the crown jewel of evolution.
       | 
       | Au contraire. We are a pretty shitty product of evolution and are
       | a danger to evolution itself since we acquired the intelligence
       | and technology to change DNA of creatures based on our whims. (We
       | did this for centuries through artificial selection. Now we can
       | do it more directly)
        
         | fimbulvetr wrote:
         | That's not the implication I got at all. Coupled with the
         | photo, it really did seem like it would be an "Alien Plant" had
         | I been able to be there. As far as "working together" - wow,
         | you _really_ look that literally. I don 't think he meant they
         | were conspiring by text on whatsapp.
        
         | qubex wrote:
         | Even the title is absurd: the atmosphere didn't become
         | breathable -- life evolved to breathe the atmosphere.
        
           | NoahKAndrews wrote:
           | There's an inferred "to us"
        
             | logdap wrote:
             | [dead]
        
       | ur-whale wrote:
       | I don't get the concept at all.
       | 
       | Earth's atmosphere didn't "become breathable".
       | 
       | Rather, species evolved to survive within whatever the
       | environment was at the time and also had an effect on the
       | atmosphere itself, thereby killing other species in a very
       | complicated dance.
       | 
       | The whole notion implied by the title is wrong.
        
         | phkahler wrote:
         | Yeah, all those animals flopping around gasping for air until
         | _finally_ the air became breathable... ;-)
        
       | thangalin wrote:
       | My book touches upon the great oxygenation event, relating it to
       | the production of oil deposits, which we burn at alarming rates:
       | 
       | https://impacts.to/downloads/lowres/impacts.pdf#page=11
        
       | classified wrote:
       | It has always been breathable, it just changed for who.
        
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       (page generated 2023-05-17 23:01 UTC)