The exact origin of life on Earth is still a topic of scientific investigation and debate. However, there are several theories about how the building blocks of life may have formed. One prominent hypothesis is the "primordial soup" theory, which suggests that the early Earth's oceans contained a rich mixture of organic molecules necessary for life.
According to this theory, around 4 billion years ago, the Earth's early atmosphere was composed of gases such as water vapor, methane, ammonia, and carbon dioxide. Energy sources such as lightning, ultraviolet radiation from the Sun, volcanic activity, and geothermal heat provided the necessary conditions for chemical reactions to occur.
Under these conditions, simple organic molecules, including amino acids (the building blocks of proteins) and nucleotides (the building blocks of DNA and RNA), could have formed through a process called abiogenesis or chemical evolution. These organic molecules would have accumulated in the oceans, creating a "primordial soup" of complex organic compounds.
Over time, through a process known as polymerization, these organic molecules could have combined to form more complex structures like proteins and nucleic acids. The formation of a self-replicating molecule, similar to RNA, may have marked a crucial step toward the emergence of life.
While the primordial soup theory provides a possible explanation for the formation of the building blocks of life, it's important to note that the exact mechanisms and steps involved are still the subject of ongoing scientific research and investigation.