Origin of life

The origin of life is the transition from nonliving chemistry to the first living systems. Research investigates how this transition could have occurred on early Earth or elsewhere.

RNA world: A hypothesis that RNA preceded DNA and proteins, serving as both genetic material and a catalyst. It proposes a molecule that could store information and catalyze reactions before modern cells.
Abiogenesis: The emergence of living systems from nonliving matter through natural processes. This broader term names the transition that origin-of-life research seeks to explain.
Miller–Urey experiment: A 1953 experiment that produced amino acids by sparking gases intended to model an early Earth atmosphere. It demonstrated that some organic building blocks can form from simpler chemicals under simulated conditions.
Last universal common ancestor: The most recent population from which all living organisms today descend. It is a later point in life’s history, not the first life, and its properties only indirectly constrain origins.
Astrobiology: The study of life in the universe, including its origins, evolution, distribution, and future. Origin-of-life research supplies astrobiology with criteria for evaluating habitable worlds.
Metabolism-first hypothesis: A family of hypotheses proposing that self-sustaining reaction networks preceded genetic molecules. It reverses the RNA world’s proposed order by placing organized chemistry before genes.
Nucleic acid: A polymer, such as DNA or RNA, that stores and transmits biological information. Nucleic acids provide the inheritance framework that many proposed origins must account for.
Bennu (asteroid): A near-Earth asteroid sampled by NASA’s OSIRIS-REx mission and returned to Earth in 2023. Its returned material contains organic compounds relevant to the delivery of prebiotic ingredients.
Panspermia: The hypothesis that life or its precursors spread between celestial bodies. It shifts the location of life’s beginning without explaining how life first arose.
Drake equation: A framework for estimating the number of communicative civilizations in the Milky Way from several uncertain factors. The probability that life begins is one of the uncertain factors behind estimates of civilizations.

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