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380
Aristotle (around 384-322 B.C.)
Aristotle was the first person to theorize the idea of spontaneous generation. He did so by collecting information from previous philosophers and compiling it together and expanding upon it.He explains lots of his ideas through his book The History of Animals. His idea of spontaneous generation lasted for around 2 millennia -
Period: 380 to
Spontaneous Generation Theory Widely Accepted
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550
Early speculations on spontaneous generation: (around 550-420 B.C.)
Anaximander thought that everything was made up of the elemental nature of the universe. He claimed things that are living come from the “wet” when acted on by the sun.Anaximenes, Xenophanes, Empedocles, and Democritus, important historical people, all thought spontaneous generation was a plausible way to explain the universe. -
Francesco Redi (1668)
Francesco Redi was suspicious of spontaneous generation so he conducted an experiment to test spontaneous generation. At the time maggots were known to appear from rotting meat. So he based his experiment on this common “truth”. He placed meat in a variety of flasks, some he opened some he sealed off, and some he covered with a gauze. In order for spontaneous generation to be true, maggots would need to appear in all 3 types of flasks. He found that only in the non-sealed flasks had maggots. Thi -
Period: to
People Test Spontaneous Generation
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John Needham (1745)
John Needham completed a series of experiments on broiled broths. These experiments “proved” spontaneous generation was still viable and many scientists approved. -
Lazzaro Spallanzani (1768)
Lazzaro Spallanzani modified Needham’s experiments because he thought Needham didn’t heat the broths enough. Spallanzani’s improved experiments proved that Needham was wrong and spontaneous generation didn’t work, but people argued that in order for spontaneous generation to work there must be air. -
Charles Cagiard de la Tour and Theodor Shwann (1837)
Charles Cagiard de la Tour and Theodor Shwann both published their independent theory on yeast in alcoholic fermentation. They reached their conclusions by observing yeast cells divide in the foam of left over brewed beer, and by discovering, by experimentation, that the cells would not divide if given stale air or pure oxygen. This implied that air particles in the air were the cause. -
Louis Pasteur (1859)
Louis Pasteur finally disproved the theory of spontaneous generation through his experiments. He did so by designing several s-shaped bottles pointed downwards, so gravity prevented dust and other such things from entering the bottle, filled the bottle with some nutrient-rich broth and boiled it in the bottle, then left it, observing no life for one year. This officially proved that life could not be created from nonlife even if air was present.
