Experiments in Support and Against Spontaneous Generation

In this experiments in support and against spontaneous generation post we have briefly explained about spontaneous generation experiment in of spontaneous generation theory and experiments against spontaneous generation theory.

Spontaneous Generation

The hypothesis of spontaneous generation says that life organisms can emerge from inanimate objects. According to the notion, fleas were made by dust, maggots were created by rotting flesh, and bread or wheat left in a dark corner produced mice, among other things. Although the idea that live things emerge from non-living matter may appear absurd today, the theory of spontaneous generation has been the subject of heated discussion for hundreds of years. Many spontaneous generation experiment were carried out at this time to both prove and disprove the notion.

Spontaneous Generation Experiment

Support of Spontaneous Generation

The doctrine of spontaneous generation was coherently synthesized by Aristotle, who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms, and was taken as scientific fact for two millennia.

Aristotle

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation, the notion that life can arise from non-living matter.  

Aristotle proposed that life arose from non-living material if the material contained pneuma (“vital heat”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water.

John Needham

The English naturalist John Turberville Needham was in support of the theory. Needham found that large numbers of organisms subsequently developed in prepared infusions of many different substances that had been exposed to intense heat in sealed tubes for 30 minutes.

Assuming that such heat treatment must have killed any previous organisms, Needham explained the presence of the new population on the grounds of spontaneous generation.

Others

By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared.

Jan Baptista van Helmont, a seventeenth century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks.

Against Spontaneous Generation

Redi’s experiment

Francisco redi did conclusive and well-designed spontaneous generation experiment to disapprove the theory of spontaneous generation. He placed meat and fishes in 3 separate jars. Jar No. 1 was left open, No. 2 was covered with gauze and the third one was covered with paper.

The meat/fishes decayed in all three jars and attracted flies. In Jar No. 1, flies entered and layed eggs which eventually gave birth new larvae. Whereas in Jar No. 2, flies couldn’t be able to enter and no larve was found inside the jar.

But flies laid eggs on gauze that produced larvae. This has conclusively proves that organisms arise from the pre-existed organism rather than non-living matter.

Spontaneous Generation

Redi’s spontaneous generation experiment to disprove the theory of abiogenesis

Spallanzani’s Experiment

In the spontaneous generation experiment to test the validity of theory of spontaneous generation. In this spontaneous generation experiment, spallanzani has prepared animal or vegetable broth and boiled them for several hours and then either remained open or sealed immediately.

This broth remained free from microorganism growth. He concluded that high temperature boiling had killed all microorganisms and in the absence of microorganism life could not appear. The broth left open or exposing of sealed broth shows growth of microorganisms.

Spontaneous Generation

Spallanzani’s spontaneous generation experiment to disprove the theory of abiogenesis.

Louis Pasteur Experiment

In another conclusive spontaneous generation experiment, Pasteur had designed spontaneous generation experiment in a flask with “S” shaped curve tube. He took hay infusion in the flask and boiled for several minutes. After cooling, the steam condensed into the lower part of tube and act as barrier to stop the entry of microorganisms.

No life appeared in the flask for several months. Analysis of condensed water indicates appearance of microorganism in the neck of the tube. Breaking of “S” tube allowed the growth of microorganisms in the flask.

Spontaneous Generation

Pasteur’s spontaneous generation experiment to disprove the theory of abiogenesis.

Theory of Catastrophism

This is the extension of the theory of special creation. This theory assumes that life is originated by the creation and it is followed by catastrophe due to geographical disturbances.

Each catastrophe destroyed the life completely whereas each creation forms life different from the previous one.

Hence, each round of catastrophe/creation is responsible for evolvement of different types of organisms on earth. The critism of the current theory is same as previous one, No scientific spontaneous generation experiment to support the hypothesis and mostly be based on imaginary concepts.

Theory of Cosmozoic

This theory was put forward by Richter and strongly supported by Arrhenius. The theory assumes that life was present in the form of resistant spores and appeared on earth from other planet.

Since the condition of earth was supporting the life, these spores grew and evolved into different organisms. This theory was also known as “theory of panspermia or spore theory”.

The theory initially got the support from the fact that fossils of microorganism were found in meteorites in 1961. But no mechanism is known about the transfer of spores from other planet or whether these spores could survive the journey in space.

The absence of life forms on any planet except earth and no details about the spores, its origin and mechanism of crossing interplanetary space and reaching earth.

In addition, this theory doesn’t add much into the fundamental details about origin of life. No scientific spontaneous generation experiment was given to support the theory. As a result, the hypothesis didn’t receive much attention.

Theory of Eternity of Life

This theory assumes that life had no beginning or end. It believes that life has ever been in existence and it will continue to be so ever.

It further believe that there is no question of origin of life as it has no beginning or end. The theory is also known as steady state theory.

The main objection against the proposed theory that it could not be able to explain; evidences support that initially earth forms and then life appeared on it. Where life exist before the formation of earth? 

Further Readings

Reference