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Redi’s experiment
Francesco Redi, an Italian physician and poet, made the first serious attack on the idea of spontaneous generation in 1668. At that time, it was widely held that maggots arose spontaneously in rotting meat. To achieve his goal of proving spontaneous -
Needham’s rebuttal
Despite Redi's experiment, belief in spontaneous generation persisted. The microscope revealed microorganisms that seemed to arise spontaneously, leading some to argue it applied to microbes, not larger organisms. In 1745, John Needham boiled broth, sealed it, and observed microbial growth, concluding spontaneous generation was real. His findings contradicted Redi’s conclusions, reinforcing the debate on the origins of life. -
Criticism from Spallanzani
Lazzaro Spallanzani, an Italian priest, challenged Needham's conclusions on spontaneous generation. He conducted meticulous experiments, boiling sealed flasks of broth to eliminate microorganisms. No life appeared in the broth until the flasks were unsealed, allowing microorganisms to grow from contaminated air. Spallanzani concluded that spontaneous generation was false, and that microbes originated from external contamination rather than spontaneously forming. -
Pasteur puts spontaneous generation to rest
Louis Pasteur, a French scientist, revisited the experiment to settle the debate on spontaneous generation. He designed swan-neck bottles with downward-curved necks and boiled nutrient broth inside. For a year, no life appeared in the sealed bottles. When he broke the neck or tilted the flask to expose it to air, life forms appeared in the broth within days. Pasteur concluded that contamination came from life forms in the air, not from a “life force,” thus disproving spontaneous generation.