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400 BCE
Greeks
The idea of Spontaneous Generation first began from a Greek philosopher known as Anaximander. Later on, Aristotle, another Greek philosopher, hypothesized that one of the four means of reproduction was abiogenesis, and as long as a material contained pneuma, or also known as “vital heat”, life could be created. He spread the idea the idea through writings. -
Francesco Redi
One of the first serious attacks on Spontaneous Generation was made by Francesco Redi. Redi conducted an experiment with the claim that flies produced maggots, in which he placed meat in a jar, and covered the jar with gauze, allowing a flow of air, but with holes too small for flies to come in. He observed that “the control group had maggots on the meat and the variable group didn’t”. He concluded that maggots only form when flies come in contact with meat. -
John Needham
An English Clergyman known as John Needham challenges Redi’s claims. It was commonly known that boiling killed microorganisms. As a result, Needham boiled broth, sealed it, but it into a sealed flask, and sure enough, a while later, microorganisms grew. -
Lazzaro Spallanazani
Lazzaro Spallanazani questions Needham, and suggests that maybe the microorganisms had entered the broth from the air after the broth was boiled, but before it was sealed. Days later, the unsealed bottle was teeming with small living things that he could observe more clearly with the newly invented microscope. The sealed bottle showed no signs of life. However, though his experiment was successful, many rebutted his claims. -
Louis Pasture
Louis Pasture reconstructed the experiments of the previous scientists. He designed goose neck bottles, so that gravity would stop access of foreign materials through air. He boiled the broth, placed it in, and a year later, there was still no sign of microorganisms. When he broke off the top, exposing it to the air, microorganisms appeared. He reasoned that the contamination came from life-forms in the air. Pasteur convinced people that even if exposed to air, life did not arise from nonlife. -
John Tydall
John Tydall was a correspondent of Pasteur and was decisive in disproving spontaneous generation. He had difficulties with the effects of microbial spores. He boiled cultures to sterilise them, and some types of bacterial spores came alive through boiling. This could explain Needham’s results.
