SPONTANEOUS GENERATION THEORY: POSITIONS AND EXPERIMENTS - SCIENCE - 2025

The theory of spontaneous generation or autogenesis indicates that the origin of a certain type of life, both animal and plant, could occur spontaneously. This biological theory maintains that the new life would come from organic matter, inorganic matter or from the combination of these.

This theory arises from facts that humans face and observe on a daily basis. For example, there are times when a sealed food container is opened and a mini ecosystem is seen to have developed. There we can notice the presence of some living beings from both the vegetable and animal kingdoms.

Aristotle, philosopher who raised the Theory of spontaneous generation

From this it is worth asking: where did these organisms come from when everything there seemed inert? This question has been asked by human beings since they exist, driven by the need to preserve food, avoid the spread of unwanted specimens and promote the reproduction of species for their use.

To seek an explanation, the human being applies direct observation from his five senses. Then he came to discover the processes of reproduction of animal and plant species, and methods to conserve materials and food. With this knowledge he controlled some pests in the harvest and understood the basic cycles of nature.

Origins and history

Greece is the cradle of civilization for Western culture. Within this society we find the first philosophers who fulfill the task of researching, compiling, formulating and disseminating theories about existence.

At first this task was limited to formulating theories about the gods and the logic of their wishes and whims. The observation of the behavior of materials and nature itself led them to conclude as useless theories based on the whim of divine entities.

Thales of Miletus

In the V century a. C. (624 - 546) we find Thales of Miletus, a philosopher who was trained in Egypt. Together with other multidisciplinary wise men, he was busy looking for answers and establishing principles from observation and data comparison.

He arrives at explanations and demonstrations very advanced for his time, beginning science as a historical fact. From his speculations, he formulates invariable laws to explain the dynamics of life.

But, like his predecessors, he cannot find an explanation for phenomena outside of his logic and he resorts to explaining them through extraordinary capacities.

Socrates

In Greece itself, another important philosopher stands out on the path of formulating the explanation to the generation of life. It is about Socrates, who lived between the years 470 and 399 BC. C.

He dedicated himself to investigating the virtue of life itself and ethics, in search of his own knowledge. Its fundamental contribution is in the dialectic, a method that consists of the confrontation of opposing ideas to find the truth.

Plato

Aristocles, better known as Plato, lived between 417 and 347 BC. C. He was a disciple of Socrates and will give rise to the academy where all the specialties will be found.

Like its predecessors, it gives value to the laws of matter, but argues that matter does not exist by itself, that ideas also have their immovable laws and that these are the ones that dominate the laws of matter.

Aristotle's hypothesis

Aristotle, who also lived in Greece between 384 and 322 BC. C., was a disciple of Plato. He will be in charge of raising the theory of spontaneous generation, based on the principle that life generates itself from inert materials out of sheer necessity and the ideal conditions.

Through observation, he concluded that some life forms originated from mud heated by the sun's rays. Worms and tadpoles spontaneously sprouted from the mud.

It was evident to him that, as the water in the puddles dried up, everything that lived in it died, and that when the rains began and the pond was formed again under the heat of the sun, tadpoles, fish and worms sprouted through the air. fermentation of inert matter.

Active and passive principles

Aristotle affirmed that every living being arose from the combination of two principles: the active and the passive. For example, flies were born from the dead meat of animals (active principle) by the action of air and heat (passive principle).

Driven by these observations, Aristotle came to the conclusion that life was generated when conditions were right. Therefore, he formulated the hypothesis of abiogenesis, which is the emergence of life from non-biological elements, also known as the hypothesis of spontaneous generation.

Aristotle's position

Aristotle's contribution to the path of science is important, since it reaches its conclusions from the continuous observation of a set of factors. Generates a hypothesis or expected response and confirms it in the results.

The procedure used gives his theory an irrefutable weight that will last for hundreds of years. In time, the abiogenesis theory would be disproved. The cause has to do with the motives that sustained it for so long, and it is the management of the conditions.

In the case of Aristotle, his theories and principles were lost after his death. The Greek civilization fell into decline and was replaced by the Roman one, in which certain cultural traits were superficially maintained.

When the Roman Empire had its decline and Christianity was established, the writings of Aristotle, Plato, and other classical Greek philosophers were taken up and adapted to the convenience of the obscurantist vision, making spontaneous generation an indisputable law.

Van Helmont's position

Much later, the Belgian physicist, alchemist and chemist Jean Baptiste van Helmont, set out to confirm the theory of abiogenesis.

For this he conducted an experiment with a willow tree. He planted it in an insulated container in dry soil that had been weighed and watered it with water. After 5 years, he found that the tree had gained 75 kilos in weight, while the earth had only lost 900 grams. He concluded that water was the only vital element.

Main experiments

Van Helmont experiment

Another of van Helmont's experiments was the one he carried out with dirty clothes and wheat. He placed them in an open container. After 21 days, the sample changed its odor and fermented when combined, resulting in newborn mice of perfect physical composition.

These mice could mate perfectly with other mice born by crossing specimens of both sexes.

These experiments were carried out with controlled conditions: measurements, time and previous treatment of the soil. This was enough to confirm Aristotle's hypothesis for another hundred years.

Francisco Redi's experiments

Francisco Redi was not convinced that flies were generated by rotten meat. This Italian doctor, poet and scientist, observed that the meat was visited by flies and then tiny white worms appeared that devoured the meat and later became oval cocoons.

He took some worms and was able to observe how flies identical to those that had landed on the meat came out of these.

Based on these observations, Redi set out to perform a controlled experiment by placing pieces of meat in three equal glass containers. One covered with cloth, one covered with a cork lid, and one open. Then I would compare the results.

A few days later, the uncovered meat showed the presence of worms. While the others, despite being decomposed, did not present worms.

Repeat the experiment

To get out of the doubts, he repeated the experiment with another glass container with meat, this time covered by gauze to let the air pass. In this case, the flies left the larvae deposited on the gauze to enter the flask.

Despite Redi's demonstration, Spontaneous Generation still had many powerful defenders. For this and to protect himself from possible reprisals, he was forced to affirm that under certain conditions abiogenesis was possible.

However, he left to posterity a phrase that synthesizes his conclusions: "Everything that is alive comes from an egg, and this one from what is alive."

Needham vs.

Not satisfied with Redi's results, years later an English biologist and clergyman named John Turberville Needham secretly engages in a scientific duel with Lázaro Spallanzani. The first wanted to demonstrate the validity of spontaneous generation and the second wanted to dismantle it once and for all.

The clergyman carried out an experiment by boiling organic broths for two minutes to kill the micro-organisms by letting them rest in open containers, since he affirmed that air was essential for life. A few days later, he showed that spontaneously created living organisms reappeared.

Lazaro was not satisfied with the results of the vitalist cleric. He conducted his own experiment, but this time by boiling the broth for a longer time. He left the containers at rest, some fully closed and others open.

In the closed containers the matter remained without the presence of new organisms, while in the open ones new living organisms were generated.

Incorporation of semi-closed containers

Faced with the vitalists' arguments that, in the first place, excessive fire destroyed life and that it returned through the air, the Italian naturalist responded by carrying out the same experiment by boiling them for only two hours, but this time he added a third group of semi-closed containers that allowed air to enter.

Just as air could enter, micro organisms could also enter, which is why life was also generated in these. For this reason there was no agreement on the conclusions and the spontaneous generation could continue to rampage for another century.

The cells of life

The word cell began to be used in 1665, when the English scientist Robert Hooke observed through the microscope that cork and other plant fibers were made up of tiny cavities separated by walls, like the cells of bees.

In 1831 the botanist Robert Brown, of Scottish origin, observed the presence of uniform elements within cells, discovering the cell nucleus.

These two elements were the key so that, in 1838, the German botanist Matthias Schleiden and the Belgian zoologist Theodor Schwann realized that the two had reached the same conclusions studying two different kingdoms of nature and separately.

Birth of the cell theory

It was thus that, putting together their research - one in plants and the other in animals - they formulated the basic postulates of cell theory. Basically, this theory states that all living organisms are made up of one or more cells, each cell comes from other cells and the hereditary characteristics come from these.

Cells and their reproduction ruined the theory of spontaneous generation. However, spontaneous generation remained valid because it had not been denied.

It took several years for it to be definitively denied in 1859 by the Paris Academy of Sciences, when it called for an award to test whether spontaneous generation was valid or not.

Pasteur's experiments

The French chemist Louis Pasteur (1822 - 1895) devoted himself to studying cells. He refined the experiments of his predecessors using a type of glass container that has a very long neck in the shape of an S.

In this container he poured a previously boiled meat broth and left it to rest. He let the air penetrate his thin mouth. Finding that no life was developing in the broth, he dissected the neck of the flask.

This way he verified that the microorganisms had not been able to contaminate the culture because they had been deposited there, for which he proved that the microbes were the cause of contamination and diseases.

But although they discredited this theory because he was not a doctor, the abiogenesis theory that had been prevailing for more than two thousand years was definitely disproved.

Themes of interest

Theories of the origin of life.

Chemosynthetic theory.

Creationism.

Panspermia.

Oparin-Haldane theory.

References

1. Albarracín, Agustín (1992). Cell theory in the 19th century. Akal editions. Madrid.
2. Bedau, Mark A. and Cleland (2016). Carol E. The essence of life. Economic Culture Fund, Mexico
3. de Kruif, Paul (2012). Microbial Hunters. Mexico: Grupo Editorial EXODO
4. Goñi Zubieta, Carlos (2002). History of philosophy I Ancient philosophy. Albatros Collection, Madrid.
5. Oparin, Alexander. The origin of life. AKAL editions.