日本地球惑星科学連合2018年大会

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セッション記号 B (地球生命科学) » B-PT 古生物学・古生態学

[B-PT06] 地球生命史

2018年5月20日(日) 09:00 〜 10:30 101 (幕張メッセ国際会議場 1F)

コンビーナ:本山 功(山形大学理学部地球環境学科)、生形 貴男(京都大学大学院理学研究科地球惑星科学専攻)、守屋 和佳(早稲田大学 教育・総合科学学術院 地球科学専修)、座長:本山 功生形 貴男守屋 和佳

09:00 〜 09:15

[BPT06-01] 原始生命体の三段階進化

*丸山 茂徳1 (1.東京工業大学地球生命研究所)

キーワード:生命の起源、生命の誕生、原始生命

It is assumed that the environmental changes of the Hadean Earth drove a series of prebiotic chemical evolution to emerge first life, which should have been a passive response of primitive life to the forcing effects of environmental change. This concept is consistent with Charles Darwin’s idea explaining “no environmental change, no evolution of life”. This leads us to propose a three-step model for life’s emergence, based on perspectives derived from Hadean geological history.

First, proto-life appears underground as ectosymbiotic biofilms, facilitated by high-energy aqueous electrons from a natural nuclear reactor. Second, proto-life evolves by utilizing solar energy to survive on Earth’s Hadean surface in lacustrine environments. Finally, third proto-life, which is the first life on the Earth, emerges after struggling against the effects of a toxic Hadean ocean.

These stepwise evolution was the result of environmental changes through time. First proto-life born underground could survive with abundant energy from a natural nuclear reactor, however, they need to fit to the Hadean surface environment through splashing of nuclear geyser, resulted in the evolution to second proto-life. Finally, second proto-life encounter the toxic ocean as a result of function of plate tectonics, then first prokaryote was born. Thus, the birth and evolution of life is a response against these environmental changes, and life’s evolution is closely interlinked with the environment.