Answer: Over 4 billion years ago
Explanation: The chemical reactions between carbon and water is said to bring about life according to scientists. These reactions builds largely upon four families of chemicals (lipids, carbohydrates, amino acids, and nucleic acids).
However, the actual time of life on Earth has varying speculations from different scientists in fields of study (such as molecular biology, chemistry, oceanography, etc).
Furthermore, microfossils within hydrothermal-vent precipitates dated from 3.77 to 4.28 billion years is presumed to inhabit the oldest record of life on Earth. Hence, which is presumed to have occurred after ocean formation 4.4billion years ago.
Thus, the actual date of the chemical reactions that brought about life is not rigid, but presumed to have occurred over 4billion years ago (according to research).
