Timetoast Timeline

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Definition: Spontaneous generation is the idea that matter and life can arise out of nothing, or rising from an inanimate matter such as dust.

• Anaximander was one of the first to discuss this topic, stating that everything rose out of the elemental nature of the universe. [1]
• Aristotle was the first to start outlining the current existent philosophy. He stated: [2]

1. Everything is generated from another object, whether it be directly (a plant sprouting from a seed), or indirectly (insects developing from outside their parents). [2]

1. He explained that living things can come from non-living things because of pneuma, or “vital heat”. In his words: “Animals and plants come into being in earth and in liquid because there is water in earth, and air in water, and in all air is vital heat so that in a sense all things are full of soul. Therefore living things form when air and vital heat are enclosed.” [2]

• Vitruvius, a Roman architect, advised that libraries be placed facing eastwards to benefit from morning light, but not towards the south or the west as those winds generate bookworms. [2]
• In the late 19th century, Louis Pasteur became the center of the debate. He generated many experiments targeted to prove that organisms could not come from nothing. [3]

1. He grew a willow for five years and showed that it increased mass while the soil showed a trivial decrease in comparison. [3]

1. The process of photosynthesis was not yet understood, so he attributed the increase of mass to the absorption of water.

1. He wrote a recipe for mice (a piece of soiled cloth plus wheat for 21 days). [3]
2. He also wrote a recipe for scorpions (basil, placed between two bricks and left in sunlight). [3]

• Pier Antonio Micheli, in1729, observed that when fungal spores were placed on slices of melon the same type of fungi were produced that the spores came from, and from this observation he noted that fungi did not arise from spontaneous generation. [4][pic 1]

• Francesco Redi also contributed. Redi refuted the theory that maggots arise from decaying meat. He showed that the maggots in fact came from fly larvae laid directly on the meat. By covering the decaying meat and blocking access to the adult flies, he proved that decaying meat alone would never create maggots and that the exposed meat, when contacted by adult flies, would more often than not result in maggots. [4]

• William Harvey’s doctrine, omne vivum ex ovo, was the first definite statement opposing spontaneous generation. [2] [7]
• John Needham created a brother by boiling mutton gravy and sealing it in a jar. When microorganisms still appeared after 3 days, he claimed it as proof of spontaneous generation. In reality, the boiling time was too short to kill all of the bacteria and organisms. [7]
• Pasteur proved the theory wrong by using these key concepts: [5] [6]

1. By boiling a substance you can kill all life forms
2. A substance can still become "contaminated" after boiling
3. Exposure to air can cause contamination due to microorganisms
4. Air is the cause of spontaneous generation

Pasteur boiled the broth in a flask to kill all organisms. He heated the neck of the flask and bent it into the shape of an "S," to prevent any organisms to pass into the broth, but allowing air to enter. When Pasteur tipped the flask so that the broth would reach come into contact with the microorganisms that settled in the flask neck, the broth would become teeming with life.