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the origins of life (the atmosphere of early earth (life on early earth…

- - - - on ancient earth Nitrogen, water vapor, and carbon dioxide were the most abundant gasses.
  - - - scientists have formed a hypothesis that the first life form must have been able to live without breathing oxygen.
      - scientists also think that they were unicellular organisms
      - scientists say that they probably lived in oceans.
      - the first organisms probably resemble the archae that live in extreme conditions today.
  - - - first they recreated what early life was like on earth in their lab
      - then they placed water and a mixture of gasses into a flask
      - then they sent an electrical current through the mixture.
      - the results
        
        within a week they discovered that the mixture had darkened and that some small chemical units that if joined together could form proteins.
- - - - these experiments led to scientists formulating a hypothesis on how life arose on earth
      - scientists hypothesized that the chemical units of life gradually built up over time.
  - - - a foddil is a trace of an ancient organisms that has been preserved in rock or another substance.
      - scientists have discovered fossils that have archae like structures.
        
        these fossils have been dated back between 3.4 and 3.5 billion years old.
    - - scientists have hypothesized that the first cells could not have needed oxygen and that they were heterotrophs because they had to obtain their own food.
      - sometime down the line some of the cells may have developed the ability to make their own food.
        
        these would be the ancestors of today's autotrophs
        
        as these new autotrophs began to make their own food they produced oxygen as a waste and as the population of autotrophs increased so did the level of oxygen.