How long ago did life begin on earth?

1 Answer
Jul 18, 2016

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


Estimates: Yet to be confirmed is that some life-form might have

existed before oxygen appeared upon Earth.

Oxygen appeared on Earth about 2.4 billion years (BY) ago.

Unicellular to multicellular evolution by about 2 BY - 0.6 BY ago.

Sea life came a little later..

This was followed by leg-bearing worms, and so on.

Human-resembling anthropoid appeared by about 0.047 BY (47 million years)