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Removal of Exogenous Materials from the Outer Portion of Frozen Cores to Investigate the Ancient Biological Communities Harbored Inside
Published on: July 3, 2016
Questioning the evidence for Earth's oldest fossils
Martin D Brasier1, Owen R Green, Andrew P Jephcoat
1Earth Sciences Department, University of Oxford, Parks Road, Oxford OX1 3PR, UK. martinb@earth.ox.ac.uk
Nature
|March 8, 2002
Summary
Ancient microfossil-like structures in Western Australia are reinterpreted as non-biological artefacts. This research challenges early evidence for oxygen-producing photosynthesis and life on Earth, suggesting abiotic origins instead.
Area of Science:
- Geology
- Paleontology
- Astrobiology
Background:
- The Apex chert microfossils from Western Australia (3.465 billion years old) were considered the oldest morphological evidence for life and early oxygenic photosynthesis.
- Eleven filamentous prokaryote species were previously identified, meeting criteria for authentic Archaean microfossils.
- These findings predated other evidence for cyanobacteria and an oxygenic atmosphere by nearly a billion years.
Purpose of the Study:
- To re-evaluate the biological origin of purported microfossils from the Apex chert.
- To investigate the geological and chemical context of these ancient structures.
- To determine if the structures represent early life or abiotic processes.
Main Methods:
- Microscopic analysis (optical and electron microscopy)
- Geochemical techniques (micro-Raman spectroscopy)
- Digital image analysis and mapping of geological samples.
Main Results:
- The structures previously identified as microfossils are reinterpreted as secondary artefacts.
- These artefacts formed from amorphous graphite within hydrothermal vein chert and volcanic glass.
- No primary biological morphology was supported by the new research.
Conclusions:
- The oldest morphological evidence for life on Earth, based on Apex chert microfossils, is refuted.
- Early oxygen-producing photosynthesis is not supported by these structures.
- Abiotic processes, including Fischer-Tropsch-type synthesis, are inferred for early hydrothermal systems.
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