Spontaneous generation

Spontaneous generation was the disproven doctrine that living organisms can arise directly from nonliving matter under ordinary conditions, without descent from existing life.

Aristotle: Aristotle was an ancient Greek philosopher whose writings shaped Western accounts of nature and biology. His natural-history writings helped give spontaneous generation intellectual authority.
Biogenesis: Biogenesis is the principle that living organisms arise from preexisting living organisms. It became the experimentally supported alternative to spontaneous generation.
Louis Pasteur's fermentation experiments: Pasteur's fermentation studies showed that particular microorganisms drive specific chemical changes in foods and drinks. They connected the origin of microbial growth with practical problems in brewing and wine-making.
Abiogenesis: Abiogenesis is the study of how life could have originated from nonliving chemistry on the early Earth. Unlike spontaneous generation, it concerns a remote origin under conditions unlike ordinary present-day environments.
John Needham: John Needham was an English naturalist whose experiments with heated broths were taken to support spontaneous generation. His broth experiments became a prominent eighteenth-century case for the doctrine.
Germ theory: Germ theory holds that many diseases are caused by microorganisms. Pasteur's work against spontaneous generation helped strengthen the case for microbial life in the air.
Spallanzani's broth experiments: Spallanzani's experiments boiled broth in sealed flasks and compared it with broth exposed to air. Their design tested whether microbial growth came from the broth itself or from contamination.
Primordial soup: The primordial soup hypothesis proposes that organic compounds accumulated in early Earth's waters and contributed to life's origin. It is a modern origin-of-life proposal, not a claim that organisms arise routinely from decay.
Lazzaro Spallanzani: Lazzaro Spallanzani was an Italian biologist known for experiments on microorganisms, reproduction, and digestion. He challenged Needham by boiling broth longer and sealing its containers.
Sterilization (microbiology): Sterilization is the destruction or removal of all forms of microbial life from an object or environment. Reliable sterilization let experimenters distinguish newly formed life from surviving contamination.

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