The early Earth contained abundant radioactive materials.

早期地球含有丰富的放射性物质。

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Because early Earth lacked oxygen in its atmosphere, it also lacked a protective ozone barrier.

因为早期的地球大气中缺乏氧气，所以也缺乏起保护作用的臭氧层屏障。

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Many scientists now attribute much of the warming of early Earth to oxygen-intolerant microbes—methanogens—that produce the greenhouse gas methane.

现在，许多科学家把早期造成地球变暖的大部分原因归结于厌氧微生物——产甲烷菌——它产生了温室气体甲烷。

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"The early Earth could well have been seeded with the chemical building blocks you need for life to start, " said Dr. Smith.

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It has long been thought that the lunar body resulted from an impact between the early Earth and another planet-sized object 4.5 billion years ago.

BBC: Moon formation: New spins put on old questions

The third sub-question of how life managed to get going at all in the hostile arena of the early Earth, was neatly addressed by Charles Cockell, of Britain's Open University.

ECONOMIST: The origin of life