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  Abiogenesis (Greek, ‘birth from the inorganic’, i.e. spontaneous generation) is an ancient explanation for the origin of life, supported by superficial observation of events such as the emergence of maggots from rotting meat or the appearance of mice near a piece of old cheese. The idea that life arose, and continues to arise, spontaneously in mud was proposed by the Greek philosopher Anaximander (6th century  BCE), who suggested that a spiny fish had been the first animal to emerge onto the land and had given rise to other animals by the process of transmutation (change of form).

This basic concept was recapitulated in a variety of forms (the 9th-century Arab biologist al-Jahic refers to the spontaneous generation of life in mud in his Book of Animals) until the 17th century when William Harvey, through his work on deer embryos, proposed that ‘everything comes from the egg’ in 1651. This was followed by the Italian physician Francesco Redi\'s demonstration, in 1668, that meat which was shielded from flies bore no maggots. It began to be accepted that higher organisms could not appear by spontaneous generation but the discovery of animalcules (microorganisms) by the early microscopist Antonie van Leeuwenhoek revived the theory. It was left to Louis Pasteur to resolve the problem in response to a challenge from the French Academy of Science in 1860. Pasteur showed that a sterile medium capable of supporting the growth of microorganisms remained sterile unless seeded with microorganisms.

Although Pasteur hammered some of the final nails into the coffin of spontaneous generation, the question of how the first living organism arose (biopoiesis) was not seriously considered until the 20th century. RB

See also biogenesis; germ plasm.Further reading Paul Thompson, Abiogenesis.



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