Chemistry, the Central Science and the Origins of Life

Illustration courtesy of Windows to the Universe, http://www.windows.ucar.edu

In 1953 James Watson and Francis Crick (along with Rosalind Franklin) announced the double helix structure of DNA. With this landmark chemical discovery began the process of unraveling the details of how life is transmitted from generation to generation of bacteria, baboons and Bostonians.

At nearly the same time that Watson and Crick showed the world the chemical structure of genes, a graduate student named Stanley Miller conducted an experiment to describe chemistry as it existed before the origins of life on earth. Miller, studying under Nobel laureate Harold Urey, proposed an experiment that would recreate the conditions in the laboratory postulated on the seas and surface of the earth four billion years ago. According to Philip Ball, author of “Elegant Solutions: Ten Beautiful Experiments in Chemistry,” the experiment illustrates the “beauty of simplicity” in experimental chemistry.

Miller came to the University of Chicago in 1951 to study under Urey, who was already widely known for discovering deuterium 20 years earlier, the discovery that led to his Nobel Prize in 1934. In October of 1951, Urey gave a talk expressing his belief that the atmosphere as the earth cooled four billion years ago was reducing, not oxidizing. He suggested an experiment to show how life could have begun in a reducing atmosphere.

Miller was in the audience and told Urey he wanted to conduct the experiment. Urey tried to dissuade him at first, but relented and in September of 1952, Miller and Urey had designed a simple apparatus and had a simple list of ingredients for the prebiotic atmosphere: ammonia, hydrogen, methane, and water (see illustration at left).

According to an agreement with Urey, Miller had six months to achieve significant results. In Miller’s apparatus, water vapor-along with gaseous methane, hydrogen, and ammonia-passed through an electrical spark, then a cooling system, and finally a trap for liquid water, leaving behind the reaction products (if any). Miller and Urey hoped for a trace of an amino acid. According to Ball’s account, in less than a week, they had identified 13 of 20 amino acids found in proteins with 4% of the mixture — 10–15% of the carbon in the methane — converted to amino acids.

The next month, November of 1952, the pair was discussing their results at scientific meetings. By November, Time and Newsweek magazines were reporting life from the lab, and it became clear that Miller and Urey needed to publish their results. They selected Science magazine and, after some negotiations, their results were published on May 15, 1953 under the title, “Production of Amino Acids Under Possible Primitive Earth Conditions.”

In the half-century following his famous experiment, many leading scientists have cited the Miller-Urey experiment as an inspiration. Ball’s chapter ends with Carl Sagan calling the experiment, “the single most significant step in convincing many scientists that life is likely to be abundant in the cosmos.” For those looking for a wholly naturalistic explanation for life, the universe, and everything, the Miller-Urey experiment gave the search for the origins of life new impetus and energy.

But if the experiment has many fans, it also has legions of critics. In fact, a Google search of “Miller Urey discredited” will yield over 300 results. Among the first 10 sites are the Discovery Institute, promoters of Intelligent Design Theory, and Creation Safaris, a Young Earth Creationist site. From the information on these sites, it seems that what has been discredited about the Miller-Urey experiment is the news coverage that surrounded the experiment at the time it was announced. For people who espouse a supernatural explanation of the origin of the universe, and believe that evolutionary biology could not be part of God’s plan, the Miller-Urey experiment looks dangerous.

Because this experiment was, and is, a great source of inspiration for many and the object of loathing for many others, it is probably famous beyond its modest claims. Yet, it will always remain an example of great chemistry — a simple, beautiful, and easily repeatable experiment addressing one of the great questions of life.

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