地球最古の化石の証拠に疑問を投げかけている
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
まとめ
西オーストラリアの古代の微生物化石のような構造は,非生物学的人工物として再解釈されています. この研究は,酸素を生成する光合成と地球上の生命に関する初期の証拠に異議を唱え,その代わりに無生物的な起源を示唆しています.
科学分野:
- 地質学 地質学 地質学
- パレオントロジー・パレオントロジー
- 天体生物学 アストロバイオロジー
背景:
- 西オーストラリアのアペックス・チャート (Apex chert) の微生物化石 (3,465億年前の) は,生命と初期の酸素 fotosynthesis (光合成) の最古の形態学的証拠と考えられていた.
- これまでに11種の糸状プロカリオット種が特定され,本物のアルカイア時代の微生物化石の基準を満たしていた.
- これらの発見は,サイアノバクテリアと酸素大気の他の証拠より,約10億年前のものです.
研究 の 目的:
- アペックス研究所の微生物化石の生物学的起源を再評価する.
- これらの古代の構造物の地質・化学的文脈を調査する.
- 構造が生命の初期段階,または非生物学的過程を表しているかどうかを判断する.
主な方法:
- 顕微鏡分析 (光学顕微鏡および電子顕微鏡)
- 地化学技術 (マイクロラーマン光譜法)
- 地質サンプルのデジタル画像分析とマッピング.
主要な成果:
- 以前は微生物化石と特定されていた構造は,二次的な人工物として再解釈されています.
- これらのアーテファクトは,水熱の静脈や火山のガラスの中に無形なグラファイトから形成されたものです.
- 新しい研究により,主生物学的形態学は支持されませんでした.
結論:
- アペックス・チェルトの微生物化石に基づいた,地球上の生命の最古の形態学的証拠は否定される.
- 早期の酸素生成 fotosynthesis は,これらの構造によってサポートされていません.
- Fischer-Tropsch型合成を含むアビオティックなプロセスは,初期の熱水システムのために推論されています.
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