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Greenhouse gases have kept our earth constantly warm enough for over four billion years for living things to be able to live.

In the sentence, can we omit the word 'for'? What is the meaning of the phrase 'for over four billion years'? Thanks in advance.

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The age of the earth is more than 4 billion years. It was kept warm during this time by greenhouse gasses. The warmth provided the conditions for life to form (abiogenesis) and evolve.

Here is a better sentence.

Greenhouse gases have kept our earth warm enough for over four billion years for living things to form and then evolve.