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Jan 1, 615
First western thinker to suggest that life arose spontaneously
The first man who thinks lfe can be spontaneously was Anaximander. He believed that everything arose out of the elemental nature of the universe, which he called the "apeiron" or "unbounded". As part of his overall attempt to give natural explanations of things that had previously been ascribed to the agency of the gods, such as thunder, the heavens, and the earth, he gave the following account of life. -
Jan 1, 1580
Jan Baptist van Helmont
An Baptist van Helmont (1580–1644), a Flemish chemist, physiologist and physician produced several experiments in support of the idea of spontaneous generation. In one he showed that a willow tree after five years of growth, while the tree itself grew in size and bulk, the soil from which the tree was supposedly gaining its mass did not significantly decrease in matter. Therefore, it was attributed that the extra mass of the tree was spontaneously generating from another source. This was more du -
Redi's Experiment and Needham's Rebuttal
On 1668, an Italian scientist name Francesco Redi challenge the thoery of spontaneous generation by demonstrating that maggots come from eggs of flies. -
John Needham challenging the thoery of spontaneous
In England, John Needham challenged Redi's findings by conducting an experiment in which he placed a broth, or “gravy,” into a bottle, heated the bottle to kill anything inside, then sealed it. Days later, he reported the presence of life in the broth and announced that life had been created from nonlife. In actuality, he did not heat it long enough to kill all the microbes. -
Lazzaro Spallanzani modified the Needham experiment.
He constructed his own experiment by placing broth in each of two separate bottles, boiling the broth in both bottles, then sealing one bottle and leaving the other open.The sealed bottle showed no signs of life. This certainly excluded spontaneous generation as a viable theory. Except it was noted by scientists of the day that Spallanzani had deprived the closed bottle of air, and it was thought that air was necessary for spontaneous generation. Although his experiment was successful, -
Louis Pasteur convinced the learned world that even if exposed to air, life did not arise from nonlife.
the notable French scientist, accepted the challenge to re-create the experiment and leave the system open to air. He subsequently designed several bottles with S-curved necks that were oriented downward so gravity would prevent access by airborne foreign materials.He noted that as long as dust and other airborne particles were trapped in the S-shaped neck of the bottle, no life was created until this obstacle was removed. He reasoned that the contamination came from life-forms in the air. -
Empedocles accepted the spontaneous generation of life
Empedocles accepted the spontaneous generation of life, but held that there had to be trials of combinations of parts of animals that spontaneously arose. Successful combinations formed the species we now see, unsuccessful forms failed to reproduce.
