What is Biogenesis Theory?
Biogenesis is the production of new living organisms. Conceptually, biogenesis is sometimes attributed to Louis Pasteur and encompasses the belief that complex living things come only from other living things, by means of reproduction.
That is, life does not spontaneously arise from non-living material, which was the position held by spontaneous generation.
For example, a spider lays eggs that become other spiders. This premise historically contrasted with the ancient belief in spontaneous generation, which held that certain inorganic substances, left alone, give rise to life (such as bacteria, mice, and maggots) in a matter of days.
The principle of biogenesis is opposite to that of spontaneous generation. The person who first came up with the term biogenesis was Henry Charlton Bastian 1837–1915. He proposed to use the term biogenesis in place of spontaneous generation.
Later, Thomas Henry Huxley 1825–1895 redefined the term and proposed that the term abiogenesis be used to pertain to the process of spontaneous generation and the term biogenesis be used for the process where life arises from similar life.
These definitions prevailed. Biogenesis, thus, is the opposite of spontaneous generation. It asserts that living things can only be produced by another living thing, and not by a non-living thing.
Background on Biogenesis
The great debate over spontaneous generation theory started when A Dutch tradesman and amateur microbiologist, Antoni van Leeuwenhoek, observed small organisms in dirty water and some material he scraped from his teeth.
These organisms were called animalcules, what we call protozoans today. This discovery of microorganisms took Europe by storm and scientists were thrilled to find these animalcules.
The most pricking question in the minds of many was about the origin of these tiny creatures. This doubt had only one answer, the one provided by the theory of spontaneous generation.
Over the years, many intelligent minds came up with theories that defied the theory of spontaneous generation. Many other scientists continued their attempts to dissolve the theory of spontaneous generation.
Then, in 1858, a German doctor and pathologist, Rudolf Virchow, challenged the spontaneous generation theory by proposing the theory of biogenesis. He stated that “living cells can arise only from pre-existing living cells”.
This theory partly explained the presence of animalcules under the microscope. Because he could offer no scientific proof, arguments about spontaneous generation continued until 1861 when the issue was finally resolved by the French scientist Louis Pasteur.
The premise of biogenesis had been suspected long before being definitively demonstrated. A demonstrative experiment, which showed biogenesis right down to the bacterial level, was devised by Louis Pasteur in 1861.
Louis Pasteur’s Swan Neck Flask Experiment
French naturalist Felix Pouchet claimed in 1859 to have carried out experiments conclusively proving that microbial growth could occur without contact with air. Pouchet’s claim provoked Louis Pasteur to settle the matter of spontaneous generation.
Louis Pasteur was a French chemist and microbiologist who is well-known for the principle of vaccination, fermentation, and pasteurization. He was the first person to successfully prove the theory of biogenesis.
He proposed that there are organisms present in the air that are not visible to the naked eye. However, he emphasized the fact that air itself does not create microbes.
He carried out an experiment that would dissolve the theory of spontaneous generation and prove the theory of biogenesis.
He filled several short-necked flasks with beef broth and then boiled their contents. Some were then left open and allowed to cool. In a few days, these flasks were found to be contaminated with microbes. The other flasks, sealed after boiling, were free of microorganisms.
From these results, Pasteur reasoned that microbes in the air were the agents responsible for contaminating nonliving matter.
Pasteur next placed broth in open-ended, long-necked flasks and bent the necks into S-shaped curves. The contents of these flasks were then boiled and cooled.
The broth in the flasks did not decay and showed no signs of life, even after months. Pasteur’s unique design allowed air to pass into the flask, but the curved neck trapped any airborne microorganisms that might contaminate the broth.
Some of these original vessels are still on display at the Pasteur Institute in Paris. They have been sealed but, show no sign of contamination more than 100 years later.
Pasteur inferred that growth did not occur because dust and germs had been trapped on the walls of the curved necks. If the necks were broken, growth commenced immediately. Pasteur had not only resolved the controversy by 1861 but also had shown how to keep solutions sterile.
Pasteur showed that microorganisms can be present in nonliving matter in solids, liquids, and in air. Furthermore, he demonstrated conclusively that microbial life can be destroyed by heat and that methods can be devised to block the access of airborne microorganisms to nutrient environments.
These discoveries form the basis of aseptic techniques, procedures that prevent contamination by unwanted microorganisms, which are now the standard practice in laboratories and many medical procedures.
Modern aseptic techniques are among the first and most important concepts that a beginning microbiologist learns.
Pasteur’s work provided evidence that microorganisms cannot originate from mystical forces present in nonliving materials. Rather, any appearance of “spontaneous” life in nonliving solutions can be attributed to microorganisms that were already present in the air or in the fluids themselves.
Scientists now believe that a form of spontaneous generation probably did occur on primitive Earth when life first began, but they agree that this does not happen under today’s environmental conditions.
A Common Misconception over Theory of Biogenesis
Some creationists have argued that the law of biogenesis undermines evolutionary theory and the theory of Abiogenesis that all life originated from inorganic material billions of years ago.
However, biogenesis simply invalidates the theory of spontaneous generation it speaks to what can be accomplished in generational time spans, not over the course of thousands of generations or millions of years.
Theories about the origin of life take into account the lack of predators and the very different chemical makeup of the Earth’s atmosphere at the time.
They also consider what can be accomplished over millions of years through trial and error. Neither of these is considered in the law of biogenesis.
The theory of spontaneous generation speaks of complex life appearing fully formed in days, while theories of the origin of life postulate took millions of years of trial and error to form in conditions that no longer exist on Earth.
