Heterotroph hypothesis

The heterotroph hypothesis, also known as the Oparin–Haldane hypothesis, is a hypothesis for the origin of life that theorises that early life depended on abiotically synthesised organic structures as an energy source and for their structural components. The idea is commonly paired with abiotic organic matter formed in the atmosphere, but also aligns with hydrothermal synthesis and the consideration of extraterrestrial inputs through comets and meteorites.^[1]

History and conception

The first mention of a theory similar to the heterotroph hypothesis came from Charles Darwin, who mentioned a "warm little pond" in his theories of early life.^[2] The hypothesis was first discussed in depth by Russian biochemist Aleksandr Oparin in 1924. He believed that the first life on Earth would have formed in the ocean and been heterotrophic, and that life started as proto-cells held together by electrostatic forces called coacervates. British scientist J.B.S. Haldane independently proposed a similar idea in 1929. Unaware of Oparin's work, he proposed that ultraviolet light turned simple organic structures into more complex structures, eventually forming cells. Oparin and Haldane's work sparked greater research into abiogenesis in the field of biology. In 1952, American chemist Harold Urey conducted research on the topic and grew interested in theories of early life. This culminated in the Miller-Urey experiment in 1952, where Urey and Stanley Miller simulated conditions of Earth's early atmosphere to demonstrate the synthesis of organic compounds from inorganic structures. The experiment is central to a modern understanding of abiogenesis.

Opposition

Critics cite the marine dilution of organic matter as evidence against this hypothesis.