Molecular Evolution: From Simple Chemicals to Complex Life

One of the most influential theories regarding this transition is the concept of a "primordial soup"—a mixture of water and simple chemicals like methane, ammonia, hydrogen, and carbon dioxide. These molecules, energized by lightning, ultraviolet radiation, or geothermal heat, could undergo chemical reactions leading to the formation of more complex organic compounds. This idea gained experimental support in the 1950s through the famous Miller-Urey experiment, which demonstrated that amino acids—essential components of proteins—could be synthesized from simple gases under early Earth-like conditions.

Water, present in vast oceans even in Earth’s earliest history, played a vital role in fostering these chemical reactions. As a solvent, it allowed molecules to move freely, collide, and react. Over time, these reactions gave rise to a variety of organic molecules, including amino acids, nucleotides, lipids, and sugars. These compounds, under the right conditions, began to self-organize into more stable and complex structures.