Spontaneous Generation Theory and Experiments: Redi, Pasteur, Oparin
Theory of spontaneous generation
Spontaneous generation is a body of thought on the ordinary formation of living organisms without descent from similar organisms. The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. It was hypothesized that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh. A variant idea was that of equivocal generation, in which species such as tapeworms arose from unrelated living organisms, now understood to be their hosts. The idea of univocal generation, by contrast, refers to effectively exclusive reproduction from genetically related parent, generally of the same species.
Redi’s experiment
In 1668, the Italian doctor Francesco Redi demonstrated that the maggots found in rotting meat came from flies’ eggs.
- Redi placed pieces of the same type of meat in three jars.
- The first jar he left open, the second one he covered with a thin piece of fabric, and the third one he closed with an airtight material (cork).
- The three jars were left in the same place, and after a few days, he saw that there were maggots in the first two jars, but not the third one.
Pasteur’s experiment
In the second half of the 19th century, the French chemist Louis Pasteur demonstrated that microorganisms were not created from spontaneous generation. At this point, the theory was finally rejected.
- Pasteur placed meat soup in two flasks and bent their neck into an S-shape.
- He sterilized the liquid by heating it. After several weeks, he noticed that the soup had decomposed.
- He cut the neck of one of the flasks, and after a few days, he observed that the soup in this flask had decomposed.
- He observed that the soup in the other flask remained unchanged. Conclusion: the S-shaped neck let air into the flask, but not microorganisms. When the neck was cut, microorganisms could enter and cause decomposition.
Oparin’s theory
Oparin’s hypothesis suggested that life was developed through chemical evolution of carbon-based molecules in a primordial soup. He asserted that organic chemicals in a solution may develop if certain conditions are met. His theory suggested that primitive life on earth may have formed in the earth’s primordial ocean, and the selection process eventually created life. He drew influence from Darwin’s theory of evolution and used it to explain how primordial organisms may have formed.
Panspermia theory
The panspermia hypothesis suggests life began on Earth when the ‘seeds’ of life, already present in the universe, arrived here from space. The panspermia hypothesis proposes, for example, that microscopic life forms that can survive the effects of space (such as extremophiles) can become trapped in debris ejected into space after collisions between planets and small bodies in the system. Solar that house life.