In the Middle Ages, how life originated was not considered a problem. Everyone knew that in the beginning, God created all life. They also "knew" that life spontaneously arose from non-living things. Maggots arose from decaying meat, frogs from stagnant ponds, earthworms from manure, mice from warm moist soil and insects from the morning dew.

The belief in spontaneous generation of life predominated from the time of Aristotle until the middle of the 19th century. The first challenge to this belief came in 1668 when Francesco Redi, an Italian physician, carried out a simple experiment which indicated that maggots were not the spontaneous product of decaying meat. Redi placed a piece of meat in a jar covered with stretched Neapolitan muslin. Although the meat decayed, no maggots arose in it. Thus, Redi ascribed the "spontaneous generation" of maggots to poor observation. His conclusion: Meat merely provided a nest for the development of the insects.

In spite of this evidence, Redi refused to give up the idea of spontaneous generation entirely. He continued to believe in the spontaneous generation of intestinal and wood worms.

About this same time, Anton Van Leeuwenhoek, a Dutch scientist, discovered the world of bacteria and inspired many other scientists to construct microscopes and search for bacteria. These tiny plants and animals were found everywhere. In fact, the presence of bacteria appeared to support those who believed in spontaneous generation. It was easy to watch spontaneous generation occur because, when a decomposable substance was put in a warm place, the bacteria soon appeared where there had been none.

Leeuwenhoek and his followers did not agree with this view, so Louis Joblot, one of Leeuwenhoek's followers, boiled a hay broth for 15 minutes and placed the broth into two separate containers. One was left open to the air while the other was sealed before it cooled. This experiment was an attempt to test the idea that the bacteria got into the broth from the air. The sealed jar developed no bacteria while the open jar teemed with them. However, Joblot's experimental evidence failed to convince the world.

An interesting argument developed in the late 18th century between John T. Needham, a Scottish preacher, and Abbe Spallanzani, an Italian scientist. Both were performing experiments similar to Joblot's, but they were reaching opposite conclusions concerning the viability of spontaneous generation.

Needham was a vitalist. Vitalists believed that matter contained a vital force or principle which caused spontaneous generation. Needham performed experiments in which he boiled broths and sealed them. After a few days, micro-organisms would be present. These experiments, he claimed, proved the possibility of spontaneous generation.
Spallanzani, believing that air carried the germs of micro-organisms, conducted experiments in which the boiled broth didn't produce bacteria. Furthermore, he charged Needham with improperly sterilizing equipment. That was why Needham's experiments failed, he said.

Needham, on the other hand, responded that Spallanzani had over-heated his broths, thus destroying the vital force in the broth. He enied that he had under-heated his broths.

J.H. Rush, concerning the argument between these two, remarks,

"The trend of the argument is curious. It illustrates beautifully the tendency to believe what we want to believe."¹

The reason the argument couldn't be settled was that the results obtained were inconsistent. In 1859, the year Darwin published The Origin of Species; F. Pouchet published a work of nearly 700 pages in which he defended the vital principle and spontaneous generation. All his experimental work supported his view. Because of this, the French Academy of Sciences offered a prize to the first person who could devise an experiment which would settle the question.

Three years later, in 1862, Louis Pasteur published the proof everyone had been waiting for. In a brilliant series of experiments, Pasteur showed that micro-organisms do live in the air, an idea Pouchet had ridiculed, and proved that as long as micro-organisms in the air were kept out of the broths, no molds appeared.

George Wald, speaking of the downfall of spontaneous generation, says,

"We tell this story to beginning students of biology as though it represents a triumph of reason over mysticism. In fact it is very nearly the opposite. The reasonable view was to believe in spontaneous generation; the only alternative, to believe in a single, primary act of supernatural creation. There is no third position. For this reason, many scientists a century ago chose to regard the belief in spontaneous generation as a philosophical necessity. It is a symptom of the philosophical poverty of our time that this necessity is no longer appreciated. Most modern biologists, having reviewed, with satisfaction, the downfall of the spontaneous generation hypothesis, yet unwilling to accept the alternative belief in special creation, are left with nothing."²

Thus ends the story of the superstitious beliefs in spontaneous generation- or so we are told. Actually, the story has not ended. Philosophically, those who don't want to accept the idea that God created the world still are forced to explain the fact of life without Him. Therefore, the modern belief in spontaneous generation has taken a new form. A. I. Oparin, a Russian biochemist, who propounded a theory of the chemical origin of life, said,

"A careful survey of the experimental evidence reveals, however, that it tells us nothing about the impossibility of generation of life at some other epoch or under some other conditions."³

So instead of destroying the belief in spontaneous generation, Pasteur merely forced the issue to a point where neither side can disprove the other, at least in a conclusive manner. This, too, reminds one of what Rush said, "It illustrates beautifully the tendency to believe what we want to believe."1
However, even though neither side can disprove the other, we will see how improbable is the origin of life by chance, as suggested by Oparin and others. We also will see that there is not enough time for a purely mechanistic origin of life. Neither is there conclusive evidence that life formed in the manner postulated, nor evidence that the conditions postulated existed.

ADDITIONAL REFERENCE SOURCES

For further reading see J.H. Rush, The Dawn of Life, (Garden City: Hanover House, 1957) and A.l. Oparin, Origin of Life, (New York: Dover Publications,1965), translated by Sergius Morgulis. See especially pp. 1-28.

NOTES

1. J.H. Rush, "The Dawn of Life", Garden City: Hanover House, 1957, p. 93.
2. George Wald, "The Origin of Life", Scientific American Vol. 194, #2, p. 46.
3. A.I. Oparin, "Origin of Life", translated by Sergius Morgulis, New York: Dover Publications, 1965, p, 29.