How long ago did life begin on earth?

Answer 1

Estimates: Oxygen appeared on Earth 2.4 billion years (BY) ago; unicellular to multicellular evolution 2 BY - 0.6 BY ago.

Estimates: It is still unknown whether any living form has

existed prior to the appearance of oxygen on Earth.

Around 2.4 billion years ago (BY), oxygen first appeared on Earth.

About 2–0.6 billion years ago, unicellular to multicellular evolution took place.

The sea life arrived somewhat later.

Worms that carried legs came next, and so on.

Analogous fossils to humans first appeared approximately 0.047 BY (47 million years ago).

back then.

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Answer 2

Hunter Arthur

It is estimated that between 3.5 and 4 billion years ago, life on Earth first appeared.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.