We explain what the Spontaneous Generation Theory is, what thinkers supported it and how it was refuted.
What is the Theory of spontaneous generation?
The theory of spontaneous generation was the name given to the belief that certain forms of animal and plant life arose automatically , spontaneously, from organic matter , inorganic matter , or some combination of both.
This theory was in force for many centuries, since Antiquity . Although it is a hypothesis that could never be scientifically proven, many believed that it was verified through direct observation .
Aristotle, the Greek philosopher, believed in this theory. It was also accepted and supported by 17th and 18th century thinkers such as Sir Francis Bacon, René Descartes and Isaac Newton, who were unaware of the world of microbiology . It applied to small creatures borne by pests or parasites, such as flies, lice, ticks, and even mice.
The belief was that if the correct items (say: sweaty underwear and wheat) were left in a container, some kind of animal (say: mice) would be found after a while in their place.
This theory about the origin of life did not contradict conventional reproduction , since the creatures obtained by spontaneous generation were as perfect and identical as those born from sexual reproduction .
In this way, it could be argued that in decomposed meat, excrement or the very entrails of the human being , various forms of life were spontaneously generated, instead of thinking that they had somehow gotten there.
See also: Oparin theory
Refutation of Theory
Louis Pasteur designed an experiment to prevent the entry of microorganisms.
The theory of spontaneous generation was refuted through three specific experiments:
- Redi’s experiment (1668). Carried out by Francesco Redi, an Italian doctor, who doubted that insects could arise spontaneously from putrefaction, and assumed that at some point some adult insect had to lay eggs or larvae on decomposing matter . To verify this, he placed three pieces of meat in three different containers: one of them open and the other two sealed with gauze that allowed air to enter the jarbut not adult flies. After time passed, there were worms in the exposed meat and not in the sealed ones, although they did find fly eggs on the gauze.
- Spallanzani’s experiment (1769). Later developed by the Catholic priest and naturalist Lázaro Spallanzani, it was a kind of prelude to pasteurization. The Italian deposited meat broth in two containers, after having heated them to a temperaturethat would kill existing microorganisms and having sealed it hermetically in the container. Thus he demonstrated that microorganisms do not arise spontaneously from matter, but rather come from other microorganisms.
- Pasteur’s experiment (1861). Developed by Frenchman Louis Pasteur, father of the techniqueof food preservation known as pasteurization, consisted of the introduction of meat broth into two distillation flasks with a long and curved mouth (in the shape of an “S”), which becomes thinner as it ascends. The shape of the tube allowed the entry of air, but caused the microorganisms to remain in the lower part of the container, without accessing the meat. Thus, he heated the broth until it was sterilized and simply waited: after several days, there were no signs of decomposition, after which Pasteur proceeded to cut the mouth of the container and there, after a short time, decomposition did occur, thus demonstrating that the microorganisms came from other microorganisms and that, in general, all forms of life come from another form of lifethat precedes it.