The Beginnings of Life on Earth

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There were several gases present, namely:  Carbon dioxide: The atmosphere was likely rich in carbon dioxide, with 10 to 200 times more than today.   Water vapour: The atmosphere likely contained water vapour, which was released as the Earth cooled and oceans formed. There were Nitrogen, Methane, and Ammonia.    Although oxygen could emerge from water vapour, it quickly reacted with the methane in the atmosphere, so it was basically an anaerobic world.  Amazingly some simple, (single celled, or unicellular) life did develop.

 

There is some evidence of the microscopic anaerobic organisms, defined as organisms that do not require oxygen to survive were there.  Some are found in the human body, where they can cause abscesses and other disorders.  At the beginning of our planet’s existence anaerobic organisms survived in water, but they were strictly unicellular, and prokaryotic, the latter being defined as a type of cell that does not have a true nucleus or membrane-bound organelles.

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The earliest fossil evidence of life on earth dates to 3.7 billion years ago. They were found preserved in ancient rock samples from Greenland. Some striking evidence of them was preserved in the hard structures (“stromatolites”) they made, which date to 3.5 billion years ago. Stromatolites are created as sticky mats of microbes which trap and bind sediments into layers.

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Home - click here

The Planet's Point of View - click here

The First Big Advance - Cyanobacteria, click here

Fabulous Fungi - click here

Vegetation - click here

Insects - click here

Earthworms - click here

Birds - click here

Mammals, including humans - click here

Water based life - click here

The Calculus - click here