Progress and persistent questions in understanding the origin of life on Earth

The origin of life remains one of the most challenging questions in Earth and planetary sciences, requiring integration of early planetary evolution, geochemical environments, and experimentally validated prebiotic chemistry. This review synthesizes current evidence from Hadean Earth archives, prebiotic chemistry, and leading origin-of-life hypotheses to evaluate how planetary conditions may have facilitated the transition from non-living chemistry to biology. Because no intact Hadean crust survived, detrital zircons, particularly from the Jack Hills region of Western Australia, serve as the primary record of the Hadean Eon, preserving evidence for early crust formation, liquid water, and possible weathering by 4.4 Ga. However, significant uncertainties persist regarding surface temperatures, atmospheric composition, ocean stability, and the true impact of late heavy bombardment on habitability. The proposed settings for abiogenesis, including tidal flats, warm little ponds, submarine alkaline hydrothermal systems, evaporative soda lakes, nuclear reactor–geyser systems, and extraterrestrial delivery models, are critically examined to assess their respective physicochemical advantages and limitations. This review also includes the experimental advances demonstrating plausible pathways for the synthesis of amino acids, nucleobases, sugars, fatty acids, thiols, phosphorylated intermediates, protometabolic networks, and membrane self-assembly. By comparing these environments and reaction pathways within the context of realistic early Earth conditions, we highlight the growing evidence that no single setting fully satisfies all requirements for life’s emergence. Instead, current data increasingly support a scenario in which complementary processes operating across interconnected and evolving environments collectively enabled the assembly, concentration, stabilization, and integration of prebiotic molecules. Despite substantial interdisciplinary progress, the transition from geochemistry to biology remains unresolved, underscoring the need for integrative frameworks to explain how non-living chemistry ultimately became life. Integrates Hadean geology with experimental prebiotic chemistry. Evaluates habitats for abiogenesis across early Earth settings. Explores building blocks, protometabolism, and homochirality.