Final answer:
Life's organic building blocks were formed around 4 billion years ago on Earth, possibly from organic material accumulated in the oceans. This was a precursor to the development of life, as evidenced by the successful Miller-Urey experiments and fossil records of ancient microbial existence.
Step-by-step explanation:
The first organic molecules, which are the building blocks of life, likely formed on Earth around 4 billion years ago. It's generally accepted that these organic molecules evolved before cells, setting the stage for life to develop. When Earth's bombardment by large impacts ceased, a more peaceful environment allowed for the accumulation of organic material in the oceans. Such material is thought to have contributed to the development of organisms. The Miller-Urey experiments in the 1950s supported this idea, as they were able to produce organic compounds under simulated early Earth conditions. RNA may have been among the first organic molecules to form, potentially representing the beginning of life on Earth.
While the exact sequence of events from molecules to biology remains unclear, fossil evidence suggests the presence of microbial life on Earth at least 3.5 billion years ago. Life's complexity has increased over billions of years, influenced by various planetary changes. Essential for the progression to living organisms were organic molecules that could replicate themselves, extracting energy from their environment and encoding genetic information.