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350
Aristotle (BCE)
Aristotle, a Greek scientist/philosopher, combined the ideas of all Greek philosophers before him and published History of Animals and Generation of Animals to explain his version of the phenomenon known as Spontaneous Generation. Just like those before him, he believed that all organisms were a mixture of the four elements and the four principles (hot, cold, dry, wet). However, he added the concept of an animating force: “pneuma”, which translates to “soul”. -
500
After Anaximander (BCE)
After Anaximander came Anaximenes (his pupil), Xenophanes (founder of Eliatic school), Empedocles (philosopher), Democritus (philosopher), and Anaxagoras (philosopher). All were influenced by the views of Anaximander – teaching that all organisms were created by the elements. -
Jan 1, 600
Anaximander (BCE)
Anaximander, a Milesian (present day Turkey) philosopher, was the first to suggest that life could arise from nothing. He believed that all organisms arose out of elements of the universe. -
Francesco Redi
After centuries of believing in this idea, many scientists began to question its legitimacy. Francesco Redi’s experiment was the first significant attack on the theory. After his experiment, in which he placed meat in different jars (sealed, gauzed, opened) to see if maggots really appeared out of thin air, he found that maggots only appeared in the opened ones, which meant that the theory was incorrect. Unfortunately, people choose to disregard this. -
John Needham
Unlike Redi, there were some firm believers in this theory. John Needham, an English clergyman, experimented by boiling broth to see if organisms would spontaneously appear after being killed off by the heat. They did. But this miraculous result was because the microorganisms in the air were able to enter the broth before the flask was sealed. Of course, this wouldn’t be recognized until Lazzaro Spallanzani challenged this experimentation. -
Lazzaro Spallanzani
Lazzaro Spallanzani, an Italian priest, realized the mistake of the broth boiling and decided to modify the testing by sealing the flask first so that it would eliminate the uncertainty of air entering. After experimentation, he found that no organisms grew; however, people still decided not to disregard the theory of Spontaneous Generation. -
Louis Pasteur
Finally, Louis Pasteur, a young French chemist, put the theory to rest. He did this by combining Needham and Spallanzani’s experimentations together – boiling broth in a flask, but heating the neck of the flask, bending it into the shape of an “S”. This allowed air to enter, but didn’t allow microorganisms to reach the broth (they settled in the neck instead). It refuted the theory and convinced everyone that these microorganisms do not just materialize out of thin air.
