初期の地球に大型の小惑星が衝突して生態系が破壊された
N H Sleep1, K J Zahnle, J F Kasting
1Department of Geophysics, Stanford University, California 94305, USA.
Nature
|November 9, 1989
まとめ
初期の地球は,致命的な小惑星の衝突にもかかわらず,早々44億440万年前には非光合成生命を支えた可能性がある. 複雑な生態系が現れる前に,光合成生物が進化するための狭い窓が存在していました.
科学分野:
- 初期の地球の条件.
- 天体生物学 アストロバイオロジー
- 生命の起源 生命の起源
背景:
- 初期の地球に大型の小惑星が衝突し,海洋水を蒸発させ,地球全体で致命的な環境を作り出した.
- 初期の地球の居住可能性は,光合成から独立した生態系にまで広がったのかもしれない.
研究 の 目的:
- 初期の地球の居住可能性のタイムラインを調査し,光合成生命の出現に焦点を当てます.
- 非光合成生態系による継続的な居住可能な最古の期間を決定する.
主な方法:
- 地質学的および古生物学的記録の分析.
- 初期の地球の環境条件とインパクトイベントのモデリング.
主要な成果:
- 地球は,現在 (Gyr BP) よりも4億4400万年前に,非光合成生態系によって居住可能であったかもしれない.
- 3.8 Gyr BP 以降,光合成生物の進化の可能性と,化石記録における高度な光合成生態系の出現の間には,制限された期間が存在します.
結論:
- 非光合成生命は,これまで考えられていたよりもはるかに早く地球上に確立していた可能性があります.
- 複雑な光合成生態系の進化は,地球の歴史における特定の,比較的遅い窓に制限されていた.
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