They could help scientists understand not just when higher life forms evolved, but why.

它们将不仅仅帮助科学家理解高等生物何时出现，还有为何出现的问题。

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Suppose the evolution of higher life forms takes another couple billion years, as it did here.

再假设更高级形式的生命要再花几十亿年才能进化，就如地球上所经历的那样。

youdao

And we also know that several have happened in the past leading to the extinction of all higher life forms at the time.

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