Stromatolites from
Bolivia, from the
Proterozoic (2.3 billion years ago). Vertical polished section.
The origin of life on Earth is a scientific problem which is not yet solved. There are many ideas, but few clear facts.
Most experts agree that all life today evolved by common descent from a single primitive lifeform. It is not known how this early life form evolved, but scientists think it was a natural process which happened about 3,900 million years ago. This is in accord with the philosophy of naturalism: only natural causes are admitted.