Short answers, pulled from the story.
The earliest physical evidence of life dates back to 3.7 billion years ago, found in the Nuvvuagittuq Greenstone Belt of Northern Quebec. These microbialites in banded iron formation rocks suggest that microorganisms lived within hydrothermal vent precipitates shortly after the oceans formed 4.4 billion years ago. Some fossils potentially date as far back as 4.32 billion years.
Stanley Miller and Harold Urey conducted a groundbreaking experiment in 1952 that demonstrated how organic molecules could form spontaneously from inorganic precursors. They used a highly reducing mixture of gases including methane, ammonia, and hydrogen along with water vapor and subjected it to electrical discharges to simulate lightning. This process successfully synthesized amino acids and validated the Oparin-Haldane hypothesis.
The RNA world hypothesis was proposed in 1962 by Alexander Rich and coined by Walter Gilbert in 1986. This theory suggests that self-replicating and catalytic RNA molecules existed before the evolution of DNA and proteins. The structure of the ribosome serves as the smoking gun of this hypothesis with a central core of RNA that catalyzes peptide bond formation.
Deep-sea hydrothermal vents form where hydrogen-rich fluids emerge from below the sea floor and react with carbon dioxide-rich ocean water. These reactions produce exothermic energy that drives the synthesis of simple organic molecules like methanol, formic acid, acetic acid, and pyruvic acid. Microscopic compartments within these vents composed of iron-sulfur minerals such as mackinawite provide a natural means of concentrating organic molecules.
Geologist Ulrich Schreiber and physical chemist Christian Mayer proposed that the continental crust, specifically tectonic fault zones, provided a stable and well-protected environment for long-term prebiotic evolution. These fault zones are located at depths of around 1000 meters and offer optimal conditions for phase transfer reactions between liquid water and supercritical carbon dioxide. This environment allows lipophilic organic molecules to accumulate and precipitate while fostering the formation of vesicles.
A 2016 study identified 355 genes likely present in the last universal common ancestor which lived over 4 billion years ago. This organism was anaerobic, thermophilic, and dependent on a geochemically active environment rich in hydrogen, carbon dioxide, iron, and transition metals. LUCA utilized the Wood-Ljungdahl pathway to derive energy by chemiosmosis and possessed hundreds of genes encoded in the universal DNA genetic code.