Franklin M. Harold
- Published in print:
- 2014
- Published Online:
- May 2015
- ISBN:
- 9780226174143
- eISBN:
- 9780226174310
- Item type:
- chapter
- Publisher:
- University of Chicago Press
- DOI:
- 10.7208/chicago/9780226174310.003.0009
- Subject:
- Biology, Biochemistry / Molecular Biology
The discovery of fossil bacteria sixty years ago quadrupled the length of life's known history, and initiated the search for geological traces of cell evolution. Earth has hosted life for as long as ...
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The discovery of fossil bacteria sixty years ago quadrupled the length of life's known history, and initiated the search for geological traces of cell evolution. Earth has hosted life for as long as it has offered a habitable environment, more than three billion years. Microbial communities of the Proterozoic and late Archean eras included various Bacteria (cyanobacteria go back some 2.5 billion years), and indirect evidence points to the presence of Archaea also. Eukaryotic fossils that can be assigned to contemporary lineages are much more recent, a billion years or less. However, there is a growing trove of much older fossils that are generally interpreted as eukaryotic, and also evidence from biomarkers. Taken together, they indicate that the eukaryotic lineage is ancient, at least 2 billion years and probably deeper. The last common ancestor of contemporary eukaryotes was the product of a prolonged history. The findings mesh with geological traces of the rise of atmospheric oxygen, and can be placed on a general timeline of cellular evolution.Less
The discovery of fossil bacteria sixty years ago quadrupled the length of life's known history, and initiated the search for geological traces of cell evolution. Earth has hosted life for as long as it has offered a habitable environment, more than three billion years. Microbial communities of the Proterozoic and late Archean eras included various Bacteria (cyanobacteria go back some 2.5 billion years), and indirect evidence points to the presence of Archaea also. Eukaryotic fossils that can be assigned to contemporary lineages are much more recent, a billion years or less. However, there is a growing trove of much older fossils that are generally interpreted as eukaryotic, and also evidence from biomarkers. Taken together, they indicate that the eukaryotic lineage is ancient, at least 2 billion years and probably deeper. The last common ancestor of contemporary eukaryotes was the product of a prolonged history. The findings mesh with geological traces of the rise of atmospheric oxygen, and can be placed on a general timeline of cellular evolution.
