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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
An electron micrograph of Bacteria
Image courtesy of JPL/NASA

The First Living Cells

The first beings were probably much like coacervates. As a group, these bacteria were heterotrophic , meaning that they ate food which came from somewhere else. Because there was virtually no oxygen in the atmosphere at this time, these bacteria did not breathe oxygen. The fossils of some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.

For food, these early bacteria probably consumed naturally occurring amino acids. Amino acids, sugars, and other organic compounds formed spontaneously in the atmosphere then dissolved in liquid water. Upon digesting these molecules, early bacteria produced methane and carbon dioxide as waste products.

Over time, new life forms evolved which were able to get their energy from a different source -- the Sun!

Last modified June 4, 2010 by Randy Russell.

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