Many scientific explanations for the origin of DNA and life have been proposed over the years. These hypotheses explain how inorganic molecules became organic monomers, such as amino acids, sugars, phosphates, and bases.
But this still didn't explain where living things came from. If macromolecules were able to form on early Earth, this still
leaves us with the question of how the polymers would have become self-replicating, a basic criteria for life. There
are several ideas but little certainty. Some of the common ideas include: the RNA world hypothesis, the "genes first"
hypothesis, and the "metabolism first hypothesis.