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Spontaneous Generation and Evolution

This post will look at the origins of spontaneous generation, how it was eventually disproven, and the rise of evolution in its place.

History of Spontaneous Generation

Spontaneous generation was the belief that living organisms could come from nonliving matter. This theory of life was believed for over 2,000 years until the work of Louis Pasteur and Charles Darwin in the late1850’s. The ideas of spontaneous generation begin in ancient Greece.

A presocratic philosopher named Anaximander is believed by many to be the first purpose that life began spontaneously, around the 5-6th century BCE. In so doing, Anaximander removed the agency of the Greek gods in the creation of man. About200 years later, Aristotle expanded Anaximander’s thoughts in several books that proposed spontaneous generation.

By the middle ages and the enlightenment, several experiments claimed to prove the validity of spontaneous generation. Below are several examples, along with some of the errors in the conclusions.

  • Jan Baptist van Helmont noted that trees grew bigger without any noticeable decrease in the soil around the tree. This indicated to him that the tree was growing spontaneously when the reality was that scientists were not yet familiar with the mechanisms of photosynthesis.
  • Van Helmont also mentions an experiment with wheat. He stated that if you put wheat in a jar and wrapped it in dirty wet underwear, a mouse would “appear” and eat the wheat. In actuality, the mouse would crawl inside when nobody was looking to eat the wheat.
  • Another experiment involved the fact that rotten meat would start to have maggots consume it. With the invention of the microscope, scientists realized that flies were laying eggs on the meat, and that was where the maggots came from. In addition, the experiment was further disproven by wrapping the rotten meat in cheesecloth which prevented the flies from laying their eggs on the meat. Francesco Redi conducted this falsification in 1668.

All of the examples above sowed seeds of doubt, but scientists often would not accept this evidence. This was partly because spontaneous generation was an old and established theory and firmly entrenched as the answer for the origins of life. Rejecting this was difficult personally and professionally, and one did not stand to gain much for this sacrifice. This all began to change with the work of Louis Pasteur.

Louis Pasteur

Pasteur had a radical idea at the time. He proposed to test the theory of spontaneous generation. He did a variation of the pond scum observation that supposedly supported spontaneous generation. Supporters of spontaneous generation stated that the green stuff (algae) grows by itself along with other things in the water, which provided additional evidence of life developing spontaneously. This same scum would grow even in water that was boiled first and then left outside long enough.

Pasteur conducted an experiment in which he placed chicken broth inside a flask. He then boiled the chicken broth to kill anything that was in it. What was different in this experiment from others was that flask had an s-shape top. This s-shape prevented anything from the air from getting inside the chicken broth because this would involve the particles traveling from the sky and then up the s-shape top of the flask.

Pasteur found that nothing ever grew inside the chicken broth. He replicated the experiment in different locations, elevations, weather, etc., and continued to get the same results. When he shared his results, it was the final nail in spontaneous generation. Others had provided evidence, but Pasteur provided evidence at a microbial level. Pasteur was developing his germ theory and was looking to disprove spontaneous generation to strengthen his germ theory position. However, he also had sunk the main view on the origin of life in the process. All this happened in the year 1859.

Darwin & Evolution

Naturally, scientists were distraught at the loss of spontaneous generation. Now the question was, where did humans come from? If life comes from life, does this mean that there is some supernatural explanation for life? Acknowledging a supernatural power that cannot be observed and tested is considered unscientific; however, in one of the incredible coincidences of scientific history, Charles Darwin published his theory on evolution in 1859. In other words, the same year that spontaneous generation was disproven scientifically, another explanation for the development of life was already on the scene.

There had been rumbles of evolution in the past, such as Lamarckianism, Catastrophism, and Uniformitarianism. The difference now was that the audience was much more receptive to another explanation after the most established view was destroyed. Suddenly, Darwin’s theory became the primary explanation for explaining life.

Darwin’s theory of evolution is the main explanation of the origin of life in the scientific community. It has achieved perhaps the same unquestioned standard of acceptance as spontaneous generation. A significant difference between spontaneous generation and evolution is that it is impossible to test evolution. You cannot do an experiment to prove or disprove it. Everything that happens in evolution happens millions of years ago or takes millions of years to happen.

There is observational evidence of evolution from million years ago, but two people can see the same data and come to different conclusions, especially when they are observing things rather than actively causing something to happen, such as in an experiment. Pasteur’s experiment can still be performed today, and the results will not change. Such an experiment (that develops new species over time) is still waiting to happen for evolution, and thus the cause-effect standard of an experiment