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Period: Jan 1, 1000 to
History of Spontaneous Generation
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Jan 1, 1188
Spontaneous Generation in Christianity
The theory that living things could be spawned from non-living matter went unchallenged. For example, it was believed that the "barnacle goose" came from the "goose barnacle" crustacean. In 1188, Gerald of Wales argued that the "unnatural" generation of barnacle geese was evidence for the virgin birth in Christian religion. -
Jan 1, 1200
Reintroduction to Western Europe
Aristotle's theories, which supported spontaneous introduction, were reintroduced to Western Europe. During the 13th century, Aristotelianism reached its greatest acceptance. -
Renaissance
Spontaneous generation was accepted as fact during the Renaissance (14th - 17th centuries) -
Jan Baptist van Helmont
Jan Baptist van Helmont (1580–1644) used experiments to "prove" spontaneous generation. He grew a willow tree for five years and found it increased mass while the soil decreased. As photosynthesis was not understood, he attributed the increase of mass to the absorption of water. (exact date unknown) -
De Generatione
William Harvey published his De Generatione in 1651, in which he coined the phrase "ex ova omnia", meaning "all [life comes] from eggs". Although his work predated the microscope, he suggested that life came from invisible eggs. -
Francesco Redi's Experiment
In 1668, the Italian physicist Francesco Redi challenged the theory. Up until then, it was believed maggots were generated from rotting meat. Redi placed meat in both sealed and open containers, and found that maggots did not appear on the sealed meat, proving that they in fact came from adult flies laying eggs. -
Fungal Spores Experiment
In 1729, Pier Antonio Micheli observed that when fungal spores were placed on slices of melon, more of the same fungi was produced, and he noted that fungi did not arise from spontaneous generation.(exact date unknown) -
Challenging Redi's Experiment
Many viewed Redi's experiment as an isolated event. In 1745, John Needham conducted another experiment. It was believed that by boiling broth, organisms would be killed, so Needham put boiled broth in a sealed container. Because Needham failed to heat it thoroughly, the broth still developed life. Many thought this was proof of spontaneous generation. (exact date unknown) -
Lazzaro Spallanzani's Experiment
Lazzaro Spallanzani modified the Needham experiment. He hypothesized that Needham's broth had been contaminated. Spallanzani boiled the broth in a sealed container without any air. There was no growth in the broth, but proponents of the theory stated this was because air was needed for spontaneous generation. -
Discovery of Yeast in Fermentation
Charles Cagniard and Theodor Schwann published their discovery of yeast in alcoholic fermentation. When there was no yeast, and only sterile air, fermentation never occured. This proved microorganisms, not spontaneous generation, were the cause of fermentation. This was the discovery that 20 years later would be the basis of Pasteur's experiment. -
Pasteur's Definitive Experiment
Louis Pasteur wanted to show that if a protected substance was absent of all life, no future life would emerge, even when exposed to air. Pasteur boiled broth in a flask to kill all life, then heated and bent the neck, preventing organisms but allowing air to enter. The broth never developed life. Centuries of theory had come to a conclusion: spontaneous generation was impossible. -
Statistical Impossibility
In the modern age, spontaneous generation has been proven to be impossible. Harold Morowitz, a Yale University physicist, stated that if a broth of living bacteria was super-heated so that all chemicals were broken down into their basic building blocks, the odds of a single bacterium re-assembling by chance would be one in 10^100,000,000,000 - far surpassing the standard for statistical impossiblity (10^50).
