Timeline - History of the rebuttal of this hypothesis

Francesco Redi

1626

Italian physician, naturalist and poet. Known for his experiments on spontaneous generation, he challenged prevailing beliefs. His work laid the foundation for modern biology, disproving the idea that maggots arise spontaneously from decaying meat. Redi's work influenced the scientific method and dispelled misconceptions about the origin of life. His legacy continues to inspire scientific research. He died in 1697.

Redi's experiment

1668

It disproved spontaneous generation by showing that maggots only appeared on meat when flies had access to it. Experiment: (three jars with meat)
1 uncovered = maggots appeared
1 covered with mesh = no maggots found
1 completely sealed = no maggots emerged.

John Needham

1713

English biologist and priest. He conducted experiments in the 18th century on spontaneous generation. He believed living organisms could arise spontaneously. However, his conclusions were later challenged by Spallanzani's experiments, which showed proper sterilization prevented microbial growth. He died in 1781.

Lazzaro Spallanzani

1729

Italian biologist and Catholic priest, revolutionized science with his experiments on spontaneous generation, artificial insemination, and digestion. He disproved the theory of spontaneous generation, showing the importance of sterilization. His studies on reproduction in frogs and bats advanced understanding of reproductive processes. He died in 1799.

Needham's Rebuttal: Challenging Redi's Findings

1745

Initially supported spontaneous generation in sealed environments, but later invalidated due to flawed experiment and preexisting microorganisms. Experiment:
1 - Boiled broth placed in sealed flasks.
2 - Flasks were heated to kill existing microorganisms.
3 - Broth was left undisturbed. Microorganisms were found in the broth despite boiling and sealing the flasks, supporting the idea of spontaneous generation.

Spallanzani's Criticism: Challenging Needham's Findings

1768

Countered Needham's findings by demonstrating that proper sterilization and sealing prevented the appearance of microorganisms, refucing the idea of spontaneous generation in sealed environments. Experiment:
1- Boiled broth placed in sealed flasks.
2 - Flasks heated for an extended period to eliminate microorganisms.
3 - Flasks were properly sealed.
4 - Broth was left undisturbed. No microorganisms were found in the broth, even after an extended heating period and proper sealing.

Louis Pasteur

1822

French chemist and microbiologist. He disproved the theory of spontaneous generation through his experiments, solidifying the concept of biogenesis. Pasteur's meticulous studies on fermentation revolutionized industries. His germ theory of disease laid the foundation for modern medicine, emphasizing the role of microorganisms in causing infections. Pasteur's profound contributions continue to shape scientific and medical research, leaving an enduring legacy. He died in 1895.

Pasteur Puts Spontaneous Generation to Rest

1864

Disproved spontaneous generation, linking microbial growth to airborne microorganisms, establishing biogenesis. Experiment:
1- Prepared two flasks with a swan-neck-shaped tube, preventing dust from reaching the broth.
2- Boiled the broth in both flasks to eliminate microorganisms.
3- One flask left open, the other sealed.
4- Observed over time. Open flask showed growth, sealed flask remained microorganism-free.