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400
History of Animals by Aristotle (4th century BC)
(400 BC) Although the idea of spontaneous generaiton had already been talked about by people long before him, Aristotle was considered the first to put it together in his book, The History of Animals. There, he explained that there were animals that came from parent animals and others that grew spontaneously from non-living matter. -
Francesco Redi
In 1668, an Italian physicist named Francesco Redi performed an experiment that proved that the maggots in rotting meat that people thought were "spontaneously generating" were actually devloped from eggs that were laid by flies. This was considered one of the first experiments that proved the theory wrong. -
John Needham
In 1745, John Needham performed an experiment that showed compelling evidence for the concept of spontaneous generation by heating a chicken until all the living organisms had died and left it there, to find that microorganisms appeared in the flask. -
Lazzaro Spallanzani
Lazzaro Spallanzani decided to repeat Needham's experiment in 1767 and proved him wrong by showing that no microorganisms appeared in the flask if air was removed. -
Louis Pasteur
Louis Pasteur was able to end the debate when he showed that the air itself is filled with microorganisms that will contaminate objects that are exposed to it through an experiment where he passed air through gun filters. Entering a contest later on, he his famous "swan neck flask" experiment, where he proved that if he made it difficult for air to enter a flask and contaminate, microorganisms would not spontaneously generate. -
John Tyndall
In 1877, John Tyndall conducted an experiment that proved that there were heat-resistant organisms that would not be killed when boiled, which explained Needham's results.
