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611 BCE
First thinker of the Spontaneous Generation
The first western thinker suggested that life exist spontaneously was Anaximander, a Milesian philosopher, who believed everything arose out of the elemental nature. -
Period: 588 BCE to 428 BCE
The idea of spontaneous generation is generally accepted
It became the most common, unproven "fact".
Famous people like Anaximenes, Xenophanes, Empedocles, and Democritus, all have been trying to prove the fact, but ended with failiure. -
350 BCE
Aristotle's theory of Spontaneous Generation
“So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous generation some come from putrefying earth or vegetable matter, as is the case with a number of insects, while others are spontaneously generated in the inside of animals out of the secretions of their several organs.” 539a18-26
- From History of Animals by Aristotle -
First Experiment on the Spontaneous Generation
At that time, it was widely known that maggots arose spontaneously from rotten meat. Francesco Redi, and Italian physician published the first set of experiment challenging the Spontaneous Generation by conducting the experiment with flies and wide-mouth jars containing meat. However, he found that maggots only appeared in the opened ones, which meant that the theory was incorrect. Unfortunately, people choose to disregard this. -
Discovery of Microorganisms and Spontaneous Generation
During the later 1600's, smaller microorganisms were found due to the development of the microscope. -
John Needham's Experiment
The debate over spontaneous generation continued for centuries. John Needham, an English clergyman, was not convinced. In 1745, he set out to prove this by boiling broth in a flask, leaving it open to cool and then sealing it. In several days time, the broth was teeming with bacteria and mold. He claimed that this was proof of the existence of spontaneous generation for microorganisms. -
Lazzaro Spallanzani's Experiment
Lazzaro Spallanzani, an Italian biologist, was not convinced by John Needham's experiment and suggests that the microorganisms had entered the broth from the air after the broth was boiled, but before it was sealed. To prove his view, he tried several ways of Needham's experiment by himself. After the series of experiments, he found no organisms grew; however, people still decided not to disregard the theory of Spontaneous Generation. -
Period: to
Argument Over Experimental Results
Needham claimed that the one hour boiling time was "over-extensive" and killed the "life force." Needham also claimed that the sealed containers prevented the "life force" from reaching the soup to create the bacteria. -
Louis Pasteur's Experiment
The different results by the scientists caused Paris Academy of Sciences to offer a prize to the first person who resolves the conflict with proof. And Louis Pasteur took the prize in 1864 when he published the results of his experiment that disproved spontaneous generation. Louis Pasteur proved with this experiment that the bacteria did not spontaneously generate in the soup but came from the air. -
Spontaneous Generation and the Origins of Life
Louis Pasteur's experiments did not answer whether or not spontaneous generation ever occurred. A Russian scientist, Alexander Ivanovich Oparin, hypothesized the conditions necessary for life to come into existence on Earth in The Origins of Life. These conditions would have spontaneously generated a living organism that would form the basis of life. Some scientists found it difficult to accept that some form of "spontaneous generation" might have taken place
