by Richard Peachey

In what many consider to be a classical “origin of life” experiment, Stanley Miller synthesized some amino acids (building blocks of proteins) from a circulating mixture of gases hypothesized to represent Earth’s primordial atmosphere. Miller used an electrical spark to simulate a lightning-like energy source. Although this experiment is highlighted in virtually every textbook that discusses life’s origin, it has been criticized as “unrealistic” for several reasons including the following:

1. Miller used a “trap” to prevent the amino acids he produced from being destroyed by the very energy that formed them. This has been called “illegitimate investigator interference.” (Would such a “trap” have been available on the early Earth?)

2. Miller’s experiment produced a “racemic” mixture of both L- and D-amino acids (i.e., almost every amino acid appeared in two “mirror-image” versions called “left-handed” and “right-handed”). But all proteins made by living cells are composed of L-amino acids only.

3. The gases Miller used — methane, ammonia, water, and hydrogen — are now not generally thought to have composed the early Earth’s atmosphere.

Below is displayed a selection of quotations demonstrating that the field of “origin of life chemistry” is in much greater difficulty than students might suspect based on the glib treatment of the subject found in most of their textbooks.

“In the early 1950s, several groups were attempting organic synthesis under primitive conditions. But it was the Miller experiment, placed in the Darwinian perspective provided by Oparin’s ideas and deeply rooted in the 19th-century tradition of synthetic organic chemistry, that almost overnight transformed the study of the origin of life into a respectable field of inquiry.” (Jeffrey L. Bada and Antonio Lazcano. 2003 [May 2]. “Prebiotic Soup-Revisiting the Miller Experiment.” Science 300:746.)

“[Miller’s] discovery gave a huge boost to the scientific investigation of the origin of life. Indeed, for some time it seemed like creation of life in a test tube was within reach of experimental science. Unfortunately, such experiments have not progressed much further than their original prototype, leaving us with a sour aftertaste from the primordial soup.” (Massimo Pigliucci. 1999 [Sep-Oct]. “Where Do We Come From? A Humbling Look at the Biology of Life’s Origin.” Skeptical Inquirer 23[5]:24.)

“Many scientists now suspect that the early atmosphere was different from what Miller first supposed. They think it consisted of carbon dioxide and nitrogen rather than hydrogen, methane, and ammonia.
“That’s bad news for chemists. When they try sparking carbon dioxide and nitrogen, they get a paltry amount of organic molecules—the equivalent of dissolving a drop of food coloring in a swimming pool of water. Scientists find it hard to imagine life emerging from such a diluted soup.” (Richard Monastersky. 1998 [Mar]. “The Rise of Life on Earth.” National Geographic 193[3]:68.)

” ‘The problem of the origin of life has turned out to be much more difficult than I, and most other people, envisioned,’ says Miller, now a professor of chemistry at the University of California at San Diego.” (John Horgan. 1991 [Feb]. “In the Beginning . . .” Scientific American 264[2]:117.)

“Despite the abundant use of leading questions and tentative terminology in their origin of life discussions, the majority of textbooks exude confidence that confirmation of a naturalistic model of life’s origins is inevitable. The treatment in these textbooks stands in marked contrast to a recent review article by Klaus Dose summarizing origin of life research. In this thorough review, a strikingly different picture emerges of the current state of affairs regarding the origin of life. Dose, one of the best known origin of life researchers for the past 20 years, in The Origin of Life: More Questions than Answers (Dose 1988, p. 348) provides the following summary:

” ‘More than 30 years of experimentation on the origin of life in the fields of chemical and molecular evolution have led to a better perception of the immensity of the problem of the origin of life on Earth rather than to its solution. At present all discussions on principal theories and experiments in the field either end in stalemate or in a confession of ignorance.’ “ (Gordon C. Mills, Malcolm Lancaster, and Walter L. Bradley. 1993 [Feb]. “Origin of Life & Evolution in Biology Textbooks—A Critique.” The American Biology Teacher 55[2]:78. The Dose citation is from Interdisciplinary Science Review. 13:348-356.)

“If I were a creationist, I would cease attacking the theory of evolution — which is [in his view] so well supported by the fossil record — and focus instead on the origin of life. This is by far the weakest strut of the chassis of modern biology. The origin of life is a science writer’s dream. It abounds with exotic scientists and exotic theories, which are never entirely abandoned or accepted, but merely go in and out of fashion.” (John Horgan. 1995. The End of Science. New York: Broadway Books. p. 138.)

“Modern organisms are so sophisticated that they furnish little information about what life was like before there was a genetic code and a translation apparatus. Extraterrestrial studies have yet to provide us with an alternative life form for comparison. We are left with only a partial understanding of the origins of life that is based largely on inference and conjecture.” (Gerald F. Joyce. 1989 [Mar 16]. “RNA evolution and the origins of life.” Nature 338:217.)

” … scientists have yet to produce anything in a test tube that would shake a Fundamentalist’s faith. . . . Indeed, the more scientists learn about it, the more extraordinary life seems.” (J. Madeleine Nash. 1993 [Oct 11]. “How Did Life Begin?” Time. p. 48.)

For further reading:

“Chemical Evolution: The Problem of Improbable Proteins” <>

“Evolution’s Biggest Problem” <>