This is why not only lice, bed bugs, fleas and worms appear as guests and neighbors of our misery, born from our innermost parts and excrement, but also why if a dirty shirt is placed over the opening of a container containing wheat grains, within a few days the leaven absorbed from the cloth is transformed by the aroma of the wheat, and the wheat itself, covered in husks, turns into a mouse.
The above is an excerpt from Ortus medicinae, A work written in the first half of the 17th century by alchemist and physician Jan Baptiste van Helmont (1580-1644). In this so-called “rat recipe,” he presented one of many arguments in support of vitalism, the theory that living things can arise spontaneously from nonliving matter. Proponents of vitalism believed that life is intentionally organized and cannot be understood simply as the result of mechanical processes. Rather, life is governed by some kind of innate life force; vitalisit distinguished between the living and the dead.
By the mid-19th century, it had already been long established that neither lice nor rats occur naturally. They should have parents. But the microscope opened up a previously invisible world of microorganisms, and the study of nutrient fluids like meat broth and hay extract made it seem as if such creatures could indeed occur naturally, even if the nutrient fluids had been carefully heated and sterilized.
French scientist and physician Félix Archimede Pouchet (1800-1872) was one of the most important proponents of vitalism. In 1859 he published HeterogenyThis study claimed to present incontrovertible experimental evidence that microorganisms can spontaneously arise in sterile nutrient solutions. His reasoning suggested the existence of a God-given force that organizes all living things, a force that draws and arranges lifeless matter and acts continuously against the process of decay. However, the book’s conclusions contradicted another growing school of thought that argued that all life, including microscopic life, must have parents, and that such parents arrived at the sterile nutrient solution of Pouchet’s experiments through particles and dust in the air.
In order to resolve the problem of spontaneous generation and the heated debate surrounding it within and outside the scientific community, the French Academy of Sciences held a contest in 1859, awarding a gold medal worth 2,500 francs (equivalent to almost 100,000 euros today) to a scientist who “through rigorously conducted experiments shed new light on the so-called problem of spontaneous generation.” The question of the origin of life was to be solved and the winner chosen by a committee of eminent and reputable scientists from various related fields.
That same year, Charles Darwin, seemingly indifferent to the uproar in France, published his groundbreaking work. About the origin of species So he deliberately avoided the question of the origin of life. He instead turned his attention to what has connected all living things throughout the history of life: evolution. He calls it “evolution.”the mystery within the mystery” in the book’s preface. For Darwin, the existence of life was a sufficient starting point, and the question of the origin of life was beyond the scope of modern scientists to speculate. A few years after the publication of his masterpiece, he wrote in a letter to friends at the Royal Society: It might be better to think about the origin of matter. ”
One scientist who actually threw himself into the ring was the French chemist and pharmacist Louis Pasteur (1822-1895), whose experiments became a textbook example of how scientific hypotheses should be proven through carefully designed experimentation, repetition, and testing. In one of his most definitive experiments, he heated a nutritious meat soup to the point of sterilization in a flask with a curved neck that tapered to a narrow opening. The flask, known as a swan-neck flask, was sealed during sterilization and then opened to expose the contents to the surrounding air. Except for the use of swan-neck flasks, Pochet had conducted very similar experiments and claimed to have discovered that microorganisms could grow in sterile nutrient solutions, regardless of exposure to air. The polluted air of the streets of Paris, the air collected during an expensive expedition to the 3,300-meter-high Maladetta glacier (air was thought to be extremely pure and free of microorganisms), and even artificial air enriched with the ingredient oxygen. Pouchet and his colleagues considered one of the necessary conditions for spontaneous generation.
Illustration of a swan-neck flask used by Pasteur. Image via L. Pasteur, Pasteur works 1822–1895Internet Archive
Pasteur opened the narrow mouth of his swan-necked flask to expose the sterile culture to the oxygen-rich air that Pouchet claimed was necessary for life to begin, and although the culture came into contact with the oxygen in the air, most of the sample remained completely transparent and devoid of microscopic life forms. The cleaner the air (for example, if the flask was opened at high altitude), the fewer the broth samples will be clouded by microscopic life forms. Instead, if the neck of the flask was broken near the bottom, allowing air to come into direct contact with the liquid instead of passing through the elongated neck, the soup quickly became cloudy. The same thing happened when the intact flask was shaken so that the liquid came into contact with the inner surface of the neck. The results showed that microscopic particles suspended in the air are the carriers of life. They stuck to the inner surface of the flask neck while oxygen-rich air passed through. This was exactly the hypothesis Pasteur assumed, and the very reason behind the flask’s ingenious design.
Pouchet nevertheless defended his conclusions, claiming that Pasteur’s lengthy heating process destroyed the vitality of the soup. However, when a committee of the French Academy of Sciences responded to this criticism by demanding that the experiment be repeated, Pouchet refused, the committee verified the accuracy of Pasteur’s experiment, and unanimously declared Pasteur the winner. This debate continued for some time, motivated in part by the occasional presence of living organisms in Pasteur’s experiments. A few years later, this battle could be settled once and for all when Pasteur proved that Pochet’s equipment was contaminated by microorganisms during experiments, and scientists discovered the presence of spores (a resistant dormant stage that allows certain microorganisms to survive boiling) in certain nutritious liquids.
Even Darwin was unusual in his time for commenting on the origin of life. In a letter dated 1871, he wrote: “But if we could gestate in a small, warm pond…protein compounds were chemically formed and ready to undergo even more complex changes.” Darwin’s hypothesis about the primordial abiotic environment in which the first seeds of life once existed remains influential to this day among many researchers seeking to answer questions of the origin of life. But now, when they talk about this “pond”, they are referring to one that is nearly 4 billion years old. Additionally, the protein compounds that Darwin spoke of have been replaced in some models by self-replicating RNA molecules, which are thought to have started the chemical processes that are still ongoing in all known living things. Despite all the advances made in the name of science, no one has yet performed an experiment in which life spontaneously arises from inanimate matter. But at some point, somewhere, life arose. The question still remains how it was done.
Source: Eurozine – www.eurozine.com
