Stanley Miller and Harold Urey conducted experiments in 1952 to test the credibility of the “warm little pond” hypothesis, so named because Darwin wrote:
But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts, light, heat, electricity etcetera present, that a protein compound was chemically formed, ready to undergo still more complex changes.
The Miller-Urey experiment, as it is commonly called, subjected mixtures of water, nitrogen and compounds like carbon dioxide, hydrogen sulfide, and sulfur dioxide to heating, cooling, and electrical sparks. Later versions of the experiment, conducted by other researchers as well as by Miller and Urey, varied the temperatures, times, and compounds. Eventually, if the Darwinian hypothesis is correct, at least one combination should yield life.
Since 1952, different variations on this experiment have been performed by different researchers. To date, no life has been created by this process. Among the different approaches are those which attempt to emulate conditions in the earth’s seas, and those which try to replicate the variables found in warm ponds found in the vicinity of volcanic activity. As Armen Mulkidjanian writes,
We attempted to reconstruct the “hatcheries” of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells.
Many of these attempts to create life have been presented as attempts to see whether amino acids, or other compounds popularly called “the building blocks of life,” could have spontaneously arisen in conditions presumed to have existed on earth. Even Miller and Urey, by the time they published their results, had recast their experiment as a hunt for certain compounds, rather than the hunt for life itself; the quest was based on
the idea that organic compounds that serve as the basis of life were formed when the earth had an atmosphere of methane, ammonia, water, and hydrogen instead of carbon dioxide, nitrogen, oxygen, and water
Having failed to grab headlines in newspapers - imagine “Scientist Creates Life in a Beaker!” - Miller and Urey had to content themselves with the comment that “this type of process would be a way of commercially producing amino acids.” They might be forgiven for their overly enthusiastic quest to create life in a test-tube: Miller was, after all, only 23 years old at the time. In a 1959 write-up, he framed it thus:
Since the demonstration by Pasteur that life does not arise spontaneously at the present time, the problem of the origin of life has been one of determining how the first forms of life arose, from which all the present species have evolved. This problem has received considerable attention in recent years, but there is disagreement on many points. We shall discuss the present status of the problem, mainly with respect to the early chemical history of, and the synthesis of organic compounds on, the primitive earth.
In the half-century, and more, since then, both the chemical content of the mixtures and the amount and type of energy input have been investigated, and variations of the experiment attempted. Researchers have used infrared, ultraviolet, and visible light; alpha particles, neutrons, and other forms of bombardments have been applied. The possible combinations of chemical elements, amounts and forms of energy, and the timings of different energy applications, mean that the number of possible experiments is infinite, or nearly so.
Although the names Miller and Urey were attached to this experiment, a researcher named MacNevin in Columbus had conducted similar experiments. A New York Times article, dated March 8, 1953, reports that
In Ohio State University laboratories Dr. Wollman M. MacNevin and his associates are re-creating the earth’s conditions two billion years ago - long before there was life on this planet. “One purpose of the study,” Dr. MacNevin explains, “is to answer this scientific question: Did extreme complexity of chemical compounds develop before life appeared, or was this a result of the life processes?”
Likewise, a researcher named Wilde published in the journal Science on July 10, 1953, another experiment which apparently predates Miller and Urey. Wilde writes, after sending an electrical current, in the form of an arc, through a mixture of water vapor and carbon dioxide, that
the action of radiation on these 2 gases is of special interest in relation to the basic photosynthetic process, and also carries implications with respect to the origin of living matter on earth.
Since Wilde, MacNevin, Miller, and Urey, papers have appeared at regular intervals, reporting similar results. The quest for “life in beaker” remains unsatisfied. What implications can we draw from what has been reported thus far?
Given that the number of experimental combinations to be explored is infinite, or nearly so, we will never arrive at the point at which we can empirically satisfy the desire to have tried every combination. To draw a conclusion, therefore, we will have to discern what constitutes a representative sample of the population. The population is every conceivable combination of elements and energy forms, including the variations in timing; other variables could be considered as well, e.g., pressure.
To have a representative sample of this population, we would need to divide the population into meaningful and significant categories, and draw samples from those categories. Recursively, each category would be organized into subcategories, etc., to ensure a broad range of samples. The question arises, would there be an infinite regression of subcategories within subcategories?
In this question, we encounter the larger question which inhabits all empirical inductive sciences. If a hypothesis is to be supported, or refuted, by empirical induction, and if there is an infinite or nearly-infinite population, at which point in the process of sampling do we consider that we have “enough” evidence to form a judgment?
Given that no mixture has been found which yields life upon absorbing certain types and amounts of energy, it might be argued that the Darwinian hypothesis has failed. But given that we have not yet tested all possible mixtures, it could be argued that the evolutionary schema has not been proved implausible. Neither argument is definitive until the problems of induction and sampling have been sufficiently clarified. This is the general problem of observational empirical sciences.
For the present, the question has been side-stepped, as scientists who are seeking to create life in a laboratory have learned to consistently present their work as merely the effort to determine whether or not certain complex organic compounds could have been produced in a lifeless environment. Despite more than sixty years of persistent effort, they have failed to demonstrate that a mixture of lifeless compounds can, upon the application of energy, generate life.
At the present stage, the only clear conclusion is that there is no evidence to persuade one to believe that life spontaneously arose from nonliving matter.
