Spontaneous generation: Stuff I found on the web and compiled sequentially
Background — Spontaneous Generation Today, we take many things in science for granted. Many experiments have been performed and much knowledge has been accumulated that people didn’t always know. For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them without testing their ideas to determine the validity of these theories — in other words, they didn’t use the scientific method to arrive at answers to their questions. Rather, their conclusions were based on untested observations. Among these ideas, for centuries, since at least the time of Aristotle (4th Century BC), people (including scientists) believed that simple living organisms could come into being by spontaneous generation. This was the idea that non‐
living objects can give rise to living organisms. It was common “knowledge” that simple organisms like worms, beetles, frogs, amd salamanders could come from dust, mud, etc., and food left out, quickly “swarmed” with life. For example: Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient‐rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times. Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs. Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around. Conclusion: It was obvious to them that the mice came from the moldy grain. Observation: In the cities, there were no sewers, no garbage trucks, no electricity, and no refrigeration. Sewage flowed in the gutters along the streets, and the sidewalks were raised above the streets to give people a place to walk. In the intersections, raised stepping stones were strategically placed to allow pedestrians to cross the intersection, yet were spaced such that carriage wheels could pass between them. In the morning, the contents of the chamber pots were tossed out the nearest window. Food was purchased and prepared on a daily basis, and when people were done eating a meal, the bones and left‐overs were tossed out the window, too. A chivalrous gentleman always walked closest to the street when escorting a woman, so if a horse and carriage came by and splashed up the filth flowing in the gutters, it would land on him, and not the lady’s expensive silk gown (many of these gowns were so ornately embroidered that they were not easily washable, and neither washing machines nor dry cleaners existed). Many cities also had major rat problems. People back then may or may not have not connected the presence of rats with the spread of Bubonic Plague (Black Death, a dreaded and fatal disease), but they were probably bothered by the rats chewing on things and by the rat fleas biting them (just as cat/dog owners, even now, are bitten by the offspring of their pet’s fleas). People may not have realized that the Plague was spread by the bites of those fleas, but I imagine they knew that if only they could get rid of the rats, the pesky fleas would soon disappear, too — hence the story of the Pied Piper of Hamelin, Germany, leading all the rats out of town. Conclusion: Obviously, all the sewage and garbage turned into the rats. Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them. Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies. From this came a number of interesting recipes, such as: Recipe for bees: Kill a young bull, and bury it in an upright position so that its horns protrude from the ground. After a month, a swarm of bees will fly out of the corpse. Jan Baptista van Helmont’s recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. There will be adult males and females present, and they will be capable of mating and reproducing more mice. Helmont, Jean Baptiste van (1579‐1644) Belgian doctor who was the first to realize that there are gases other than air, and claimed to have coined the word 'gas' (from Greek cháos). Helmont identified four gases: carbon dioxide, carbon monoxide, nitrous oxide, and methane. He was the first to take the melting point of ice and the boiling point of water as standards for temperature and the first to use the term 'saturation' to signify the combination of an acid and a base. In medicine, Helmont used remedies that specifically considered the type of disease, the organ affected and the causative agent. He demonstrated acid as the digestive agent in the stomach. Helmont was born in Brussels, studied at Louvain, and 1600‐05 travelled to Spain, Italy, France, and England. From 1621 to 1642 he was persecuted by the Roman Catholic Church for his views on the cure of wounds by applying ointment to the weapon rather than the wound, which was then common. Although he did not reject the belief, he insisted that it was a natural phenomenon with no supernatural element, as set out in his treatise De magnetica vulnerum ... curatione 1621. Taking care to weigh the materials he used in chemistry, Helmont gained insight into the indestructibility of matter and the fact that metals dissolved in acid were recoverable, not destroyed or transmuted. He believed that all matter was composed of water and air, which he demonstrated by growing a willow tree in a measured quantity of earth, adding only water. His works were collectively published posthumously as Ortus medicinae 1648 Jan Baptista van Helmont (bapt. January 12, 1579 – December 30, 1644) was an early modern period Flemish chemist, physiologist, and physician. He worked during the years just after Paracelsus and iatrochemistry, and is sometimes considered to be "the founder of pneumatic chemistry". Van Helmont is remembered today largely for his ideas on spontaneous generation, his 5‐year tree experiment, and his introduction of the word "gas" into the vocabulary of scientists. Van Helmont was a man of contradictions. On the one hand, he was a disciple of Paracelsus (though he scornfully repudiated his errors as well as those of most other contemporary authorities), a mystic and alchemist. On the other hand, he was touched with the new learning based on experiment that was producing men like William Harvey, Galileo Galilei and Francis Bacon. Van Helmont is regarded as the founder of pneumatic chemistry, as he was the first to understand that there are gases distinct in kind from atmospheric air. The very word "gas" he claimed as his own invention, and he perceived that his "gas sylvestre" (carbon dioxide) given off by burning charcoal, was the same as that produced by fermenting must , which sometimes renders the air of caves unbreathable. For van Helmont, air and water were the two primitive elements. Fire he explicitly denied to be an element, and earth is not one because it can be reduced to water. Van Helmont was a careful observer of nature, and an exact experimenter who realized that matter can neither be created nor destroyed. He performed an experiment to determine where plants get their mass. He grew a willow tree and measured the amount of soil, the weight of the tree and the water he added. After five years the plant had gained about 164 pounds. Since the amount of soil was basically the same as it had been when he started his experiment, he deduced that the tree's weight gain had come from water. Since it had received nothing but water and the soil weighed practically the same as at the beginning, he argued that the increased weight of wood, bark and roots had been formed from water alone. At the same time, chemical principles guided him in the choice of medicines ‐‐ undue acidity of the digestive juices, for example, was to be corrected by alkalines and vice versa; he was thus a forerunner of the iatrochemical school, and did service to medicine by applying chemical methods to the preparation of drugs. Scientist: Jan Baptista van Helmont Flemish chemist and physician (1579–1644) Van Helmont, who came from a noble Brussels family, was educated at the Catholic University of Louvain in medicine, mysticism, and chemistry, but declined a degree from them. Rejecting all offers of employment he devoted himself to private research at his home. In 1621 he was involved in a controversy with the Church over the belief that it was possible to heal a wound caused by a weapon by treating the weapon rather than the wound. Van Helmont did not reject this common belief but insisted that it was a natural phenomenon containing no supernatural elements. He was arrested, eventually allowed to remain under house arrest, and forbidden to publish without the prior consent of the Church. He wrote extensively and after his death his collected papers were published by his son as the Ortus medicinae (1648; Origin of Medicine). Van Helmont rejected the works of the ancients, although he did believe in the philosopher's stone. He carried out careful observations and measurements, which led him to discover the elementary nature of water. He regarded water as the chief constituent of matter. He pointed out that fish were nourished by water and that substantial bodies could be reduced to water by dissolving them in acid. To demonstrate his theory he performed a famous experiment in which he grew a willow tree over a period of five years in a measured quantity of earth. The tree increased its weight by 164 pounds despite the fact that only water was added to it. The soil had decreased by only a few ounces. Van Helmont also introduced the term ‘gas’ into the language, deriving it from the Greek for chaos. When a substance is burned it is reduced to its formative agent and its gas and van Helmont believed that when 62 pounds of wood is burned to an ash weighing 1 pound, 61 pounds have escaped as water or gas. Different substances give off different gases when consumed and van Helmont identified four gases, which he named gas carbonum, two kinds of gas sylvester, and gas pingue. These we would now call carbon dioxide, carbon monoxide, nitrous oxide, and methane. Francesco Redi (February 18/19, 1626–March 1, 1697) was an Italian physician. Born in Arezzo, Tuscany, to a family of nobility, he is most well‐known for his experiment in 1668 which is regarded as one of the first steps in refuting "spontaneous generation" ‐ a theory also known as Aristotelian abiogenesis. At the time, prevailing wisdom was that maggots formed naturally from rotting meat. In the experiment, Redi took eight jars, which he divided in two groups of four: in the first jar of each group, he put an unknown object; in the second, a dead fish; in the last, raw chunk of veal. Redi took the first group of four jars, and covered the tops with fine gauze so that only air could get into it. He left the other group of jars open. After several days, he saw maggots appear on the objects in the open jars, on which flies had been able to land, but not in the gauze‐covered jars. He continued his experiments by capturing the maggots and waiting for them to metamorphose, which they did, becoming common flies. Also, when dead flies or maggots were put in sealed jars with dead animals or veal, no maggots appeared, but when the same thing was done with living flies, maggots did appear. Redi, who was born at Arezzo in Italy, studied medicine and philosophy at the University of Pisa, graduating in 1647. He was employed as personal physician to Ferdinand II and Cosimo III, both grand dukes of Tuscany. Intellectually, Redi displayed a variety of talents, being a noted poet, linguist, literary scholar, and student of dialect. On the scientific side, he laid the foundations of helminthology (the study of parasitic worms) and also investigated insect reproduction. As a biologist he is best known for his experiments to test the theory of spontaneous generation. These were planned to explore the idea, put forward by William Harvey, that flies and similar vermin do not arise spontaneously but develop from eggs too small to be seen. Redi prepared eight flasks of various meats, with half left open to the air and half sealed. Maggots were found only in the unsealed flasks where flies had been able to enter and lay their eggs. That this effect was not due to the presence or absence of fresh air was shown by a second experiment in which half the flasks were covered with fine gauze. Again, no maggots developed in these. This was one of the earliest examples of a biological experiment planned with proper controls. Redi still believed, however, that spontaneous generation occurred in such animals as intestinal worms and gall flies, and it was not until the time of Louis Pasteur that the spontaneous‐generation theory was finally discredited. In 1668, Francesco Redi, an Italian physician, did an experiment with flies and wide‐
mouth jars containing meat. This was a true scientific experiment — many people say this was the first real experiment — containing the following elements: Observation: There are flies around meat carcasses at the butcher shop. Question: Where do the flies come from? Does rotting meat turn into or produce the flies? Hypothesis: Rotten meat does not turn into flies. Only flies can make more flies. Prediction: If meat cannot turn into flies, rotting meat in a sealed (fly‐proof) container should not produce flies or maggots. Testing: Wide‐mouth jars each containing a piece of meat were subjected to several variations of “openness” while all other variables were kept the same. control group — These jars of meat were set out without lids so the meat would be exposed to whatever it might be in the butcher shop. experimental group(s) — One group of jars were sealed with lids, and another group of jars had gauze placed over them. replication — Several jars were included in each group. Data: Presence or absence of flies and maggots observed in each jar was recorded. In the control group of jars, flies were seen entering the jars. Later, maggots, then more flies were seen on the meat. In the gauze‐covered jars, no flies were seen in the jars, but were observed around and on the gauze, and later a few maggots were seen on the meat. In the sealed jars, no maggots or flies were ever seen on the meat. Conclusion(s): Only flies can make more flies. In the uncovered jars, flies entered and laid eggs on the meat. Maggots hatched from these eggs and grew into more adult flies. Adult flies laid eggs on the gauze on the gauze‐covered jars. These eggs or the maggots from them dropped through the gauze onto the meat. In the sealed jars, no flies, maggots, nor eggs could enter, thus none were seen in those jars. Maggots arose only where flies were able to lay eggs. This experiment disproved the idea of spontaneous generation for larger organisms. After this experiment, people were willing to acknowledge that “larger” organisms didn’t arise by spontaneous generation, but had to have parents. With the development and refinement of the microscope in the 1600s, people began seeing all sorts of new life forms such as yeast and other fungi, bacteria, and various protists. No one knew from where these organisms came, but people figured out they were associated with things like spoiled broth. This seemed to add new evidence to the idea of spontaneous generation — it seemed perfectly logical that these minute organisms should arise spontaneously. When Jean Baptiste Lamarck proposed his theory of evolution, to reconcile his ideas with Aristotle’s Scala naturae, he proposed that as creatures strive for greater perfection, thus move up the “ladder,” new organisms arise by spontaneous generation to fill the vacated places on the lower rungs. John Needham vs Lazzaro Spallanzani In 1745 ‐ 1748, John Needham, a Scottish clergyman and naturalist showed that microorganisms flourished in various soups that had been exposed to the air. He claimed that there was a “life force” present in the molecules of all inorganic matter, including air and the oxygen in it, that could cause spontaneous generation to occur, thus accounting for the presence of bacteria in his soups. He even briefly boiled some of his soup and poured it into “clean” flasks with cork lids, and microorganisms still grew there. A few years later (1765 ‐ 1767), Lazzaro Spallanzani, an Italian abbot and biologist, tried several variations on Needham’s soup experiments. First, he boiled soup for one hour, then sealed the glass flasks that contained it by melting the mouths of the flasks shut. Soup in those flasks stayed sterile. He then boiled another batch of soup for only a few minutes before sealing the flasks, and found that microorganisms grew in that soup. In a third batch, soup was boiled for an hour, but the flasks were sealed with real‐cork corks (which, thus, were loose‐fitting enough to let some air in), and microorganisms grew in that soup. Spallanzani concluded that while one hour of boiling would sterilize the soup, only a few minutes of boiling was not enough to kill any bacteria initially present, and the microorganisms in the flasks of spoiled soup had entered from the air. This initiated a heated argument between Needham and Spallanzani over sterilization (boiled broth in closed vs. open containers) as a way of refuting spontaneous generation. Needham claimed that Spallanzani’s “over‐extensive” boiling used to sterilize the containers had killed the “life force.” He felt that bacteria could not develop (by spontaneous generation) in the sealed containers because the life force could not get in, but in the open container, the broth rotted because it had access to fresh air, hence the life force inherent in its molecules, which contained and replenished the life force needed to trigger spontaneous generation. In the minimally‐boiled flasks, he felt the boiling was not severe enough to destroy the life force, so bacteria were still able to develop. Pasteur By 1860, the debate had become so heated that the Paris Academy of Sciences offered a prize for any experiments that would help resolve this conflict. The prize was claimed in 1864 by Louis Pasteur, as he published the results of an experiment he did to disproved spontaneous generation in these microscopic organisms. Observation(s): From Needham’s and Spallanzani’s experiments, it was known that soup that was exposed to the air spoiled — bacteria grew in it. Containers of soup that had been boiled for one hour, and then were sealed, remained sterile. Boiling for only a few minutes was not enough to sterilize the soup. Pasteur had previously demonstrated that the dust collected by drawing air through a cotton ball contained large numbers of bacteria, hence he knew that bacteria were present in the air and could be filtered out by using a cotton ball. He also knew that bacteria would settle out on the walls of a long, bent, glass tube as air was passed through it. Question: Is there indeed a “life force” present in air (or oxygen) that can cause bacteria to develop by spontaneous generation? Is there a means of allowing air to enter a container, thus any life force, if such does exist, but not the bacteria that are present in that air? Hypothesis: There is no such life force in air, and a container of sterilized broth will remain sterile, even if exposed to the air, as long as bacteria cannot enter the flask. Prediction: If there is no life force, broth in swan‐neck flasks should remain sterile, even if exposed to air, because any bacteria in the air will settle on the walls of the initial portion of the neck. Broth in flasks plugged with cotton should remain sterile because the cotton is able to filter bacteria out of the air. Testing: Pasteur boiled broth in various‐shaped flasks to sterilize it, then let it cool. As the broth and air in the containers cooled, fresh room air was drawn into the containers. None of the flasks were sealed — all were exposed to the outside air in one way or another. control group — Some flasks opened straight up, so not only air, but any bacteria present in that air, could get into them. experimental group(s) — Pasteur used some flasks with long, S‐shaped necks (swan‐neck flasks) and closed others with cotton plugs. This allowed air to enter these flasks, but the long, swan neck or the cotton balls filtered out any bacteria present in that air. He subsequently broke the long necks off some of the swan‐neck flasks. replication — Pasteur used several flasks in each of his groups. According to one freshman biology text, some of his original flasks, on display (in France), still are sterile. Data: Broth in flasks with necks opening straight up spoiled (as evidenced by a bad odor, cloudiness in previously clear broth, and microscopic examination of the broth confirming the presence of bacteria), while broth in swan‐neck flasks did not, even though fresh air could get it. Broth in flasks with cotton plugs did not spoil, even though air could get through the cotton. If the neck of a swan‐neck flask was broken off short, allowing bacteria to enter, then the broth became contaminated. Conclusion(s): There is no such life force in air, and organisms do not arise by spontaneous generation in this manner. To quote Louis Pasteur, “Life is a germ, and a germ is Life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” Activity‐Recreation of Pasteur’s Experiment (read but we are not doing) Materials Needed low‐salt broth (chicken or beef, home‐made or purchased) 2 250‐mL Erlenmeyer flasks 2 1‐hole rubber stoppers with bent glass tubing inserted (see diagram) Procedure Students should work in teams of 2 to 3 people. Each team should perform the following steps. Mark Erlenmeyer flasks accordingly: flask with stopper and glass tube going straight up flask with stopper and glass tube bent in S‐curve Place about 50 mL of broth in each Erlenmeyer flask. Place appropriate lids on flasks. Boil broth in flasks with appropriate lids on them for 30 min., then let cool. For the next several lab periods, observe the flasks and record any changes in color, turbidity, smell, etc. One very important point to note here is that Pasteur did not seek to find an answer to the broad question, “Has spontaneous generation ever occurred?” Rather, as any good scientist, he limited his scope to a very narrow piece of the picture: “Is it possible for spontaneous generation to occur given the specific conditions under which Needham (and others) claims it will occur,” i.e. the “life force?” Interestingly, in 1936, when Alexander Ivanovich Oparin, a Russian scientist, published The Origins of Life, in which he described hypothetical conditions which he felt would have been necessary for life to first come into existence on early Earth, some scientists found it difficult to acknowledge that under the very different conditions which Oparin was proposing for early Earth, some form of “spontaneous generation” might indeed have taken place. To test this hypothesis of Oparin’s, Harold Urey and Stanley Miller performed an experiment to see if a reducing environment and electricity would produce the building blocks of life. This experiment inspired many experiments in a similar vein. In 1961, Joan Oró found that amino acids could be made from hydrogen cyanide (HCN) and ammonia in a water solution. He also found that his experiment produced a large amount of the nucleotide base adenine. Experiments conducted later showed that the other RNA and DNA bases could be obtained through simulated prebiotic chemistry with a reducing atmosphere. Earth's early atmosphere Some evidence suggests that Earth's original atmosphere might have contained less of the reducing molecules than was thought at the time of Miller‐Urey experiment. There is abundant evidence of major volcanic eruptions 4 billion years ago, which would have released carbon dioxide, nitrogen, hydrogen sulfide, and sulfur dioxide into the atmosphere. Experiments using these gases in addition to the ones in the original Miller‐Urey experiment have produced more diverse molecules. Although the experiment created a mixture that was racemic (containing both L, D enantiomers), experiments since have shown that "when made from scratch in the lab the two versions are equally likely to appear, but in nature, L amino acids dominate." Other experiments have confirmed disproportionate amounts of L or D oriented enantiomers are possible. Originally it was thought that the primitive secondary atmosphere contained mostly NH3 and CH4. However, it is likely that most of the atmospheric carbon was CO2 with perhaps some CO and the nitrogen mostly N2. In practice gas mixtures containing CO, CO2, N2, etc. give much the same products as those containing CH4 and NH3 so long as there is no O2. The H atoms come mostly from water vapor. In fact, in order to generate aromatic amino acids under primitive earth conditions it is necessary to use less hydrogen‐rich gaseous mixtures. Most of the natural amino acids, hydroxyacids, purines, pyrimidines, and sugars have been produced in variants of the Miller experiment.[10] More recent results may question these conclusions. The University of Waterloo and University of Colorado conducted simulations in 2005 that indicated that the early atmosphere of Earth could have contained up to 40 percent hydrogen — implying a much more hospitable environment for the formation of prebiotic organic molecules. The escape of hydrogen from Earth's atmosphere into space may have occurred at only one percent of the rate previously believed based on revised estimates of the upper atmosphere's temperature. One of the authors, Owen Toon notes: "In this new scenario, organics can be produced efficiently in the early atmosphere, leading us back to the organic‐rich soup‐in‐the‐
ocean concept... I think this study makes the experiments by Miller and others relevant again." Outgassing calculations using a chondritic model for the early earth complement the Waterloo/Colorado results in re‐establishing the importance of the Miller‐Urey experiment. Although lightning storms are thought to have been very common in the primordial atmosphere, they are not thought to have been as common as the amount of electricity used by the Miller‐Urey experiment implied. These factors suggest that much lower concentrations of biochemicals would have been produced on Earth than was originally predicted (although the time scale would be 100 million years instead of a week). Similar experiments, both with different sources of energy and with different mixtures of gases, have resulted in amino and hydroxy acids being produced; it is likely that at least some organic compounds would have been generated on the early Earth. However, when oxygen gas is added to this mixture, no organic molecules are formed. Opponents of Miller‐Urey hypothesis seized upon recent research that shows the presence of uranium in sediments dated to 3.7 Ga and indicates it was transported in solution by oxygenated water (otherwise it would have precipitated out). These opponents argue that this presence of oxygen precludes the formation of prebiotic molecules via a Miller‐Urey‐like scenario, attempting to invalidate the hypothesis of abiogenesis. However, the authors of the paper are arguing that this presence of oxygen merely evidences the existence of photosynthetic organisms 3.7 Ga ago (a date about 200 Ma earlier than previous estimates) a conclusion which while pushing back the time frame in which Miller‐Urey reactions and abiogenesis could potentially have occurred, would not preclude them. Though there is somewhat controversial evidence for very small (less than 0.1%) amounts of oxygen in the atmosphere almost as old as Earth's oldest rocks, the authors are not in any way arguing for the existence of an oxygen‐rich atmosphere any earlier than previously thought, and they state: ". . . In fact most evidence suggests that oxygenic photosynthesis was present during time periods from which there is evidence for a non‐oxygenic atmosphere". Conditions similar to those of the Miller‐Urey experiments are present in other regions of the solar system, often substituting ultraviolet light for lightning as the driving force for chemical reactions. The Murchison meteorite that fell near Murchison, Victoria, Australia in 1969 was found to contain over 90 different amino acids, nineteen of which are found in Earth life. Comets and other icy outer‐solar‐system bodies are thought to contain large amounts of complex carbon compounds (such as tholins) formed by these processes, in some cases so much so that the surfaces of these bodies are turned dark red or as black as asphalt. The early Earth was bombarded heavily by comets, possibly providing a large supply of complex organic molecules along with the water and other volatiles they contributed. This has been used to infer an origin of life outside of Earth: the Panspermia hypothesis. During recent years, studies have been made of the amino acid composition of the products of "old" areas in "old" genes, defined as those that are found to be common to organisms from several widely separated species, assumed to share only the last universal ancestor (LUA) of all extant species. These studies found that the products of these areas are enriched in those amino acids that are also most readily produced in the Miller‐Urey experiment. This suggests that the original genetic code was based on a smaller number of amino acids ‐‐ only those available in prebiotic nature ‐‐ than the current one. Major events in the spontaneous generation vs biogenesis theory debate over time Year Event 1668 Francesco Redi attacks spontaneous generation and disproves it for large organisms 1745 John Needham adds chicken broth & hay to a flask and boils it for a short time, lets it cool, “seals” the flask with cork, and waits. Microbes grow and he proposes it as an example of spontaneous generation. 1768 Lazzaro Spallanzani repeats Needham's experiment, but removes all the air from the flask, seals it, and boils the flask considerably longer. No growth occurs. 1859 Louis Pasteur's swan‐neck flasks show that spontaneous generation does not occur. 1870 Thomas H. Huxley gives his "Biogenesis vs Abiogenesis" lecture. The speech offered powerful support for Pasteur's claim to have experimentally rejected spontaneous generation and supported biogenesis. 1877 John Tyndall publishes his method for fractional sterilization, showing the existence of heat‐resistant bacterial endospores. If conditions in the Earth biosphere are now considered to generally be oxidizing (promote chemical reactions that destroy and decompose) and have been experimentally determined to NOT support Abiogenesis, then from where 1936 did the first life arise? Hypothesis: If conditions on the early Earth were reducing (opposite of oxidizing, where chemicals can be built‐up rather than broken apart by oxidation), then under such conditions, spontaneous generation could occur. [A.I. Oparin, 1936] The Miller‐Urey experiment simulated hypothetical conditions present on the early Earth and tested for the occurrence of chemical evolution. Specifically, the experiment tested Oparin and Haldane's hypothesis that 1953 conditions on the primitive Earth favored chemical reactions (reducing environment) that synthesized organic compounds from inorganic precursors.