In 1953, Stanley Miller and his mentor Harold Urey conducted an experiment, where they were able to develop some amino acids. Urey assumed that the early Earth’s atmosphere was probably akin to that of Jupiter (i.e. ammonia, methane, and hydrogen). When these gases were mixed with an electrical charge and water, they produced amino acids, which are necessary for life. Thus, some biologists argue that this is a major piece of the puzzle in solving the mystery of first life.
However, there are a number of problems with this explanation:
First, the presence of amino acids does not even begin to solve the mystery of first life. Amino acids are simply the building blocks of life; they are not the building itself. That is, even if we have the bricks to make a building (i.e. amino acids), we would still need an architect to assemble them in their proper order (i.e. DNA). Agnostic Paul Davies writes that Miller’s experiment turned out to be “something of a dead end. Amino acids are undeniably building blocks of proteins, but they are as far from the completed product as a brick is to the Empire State Building.”
To illustrate, imagine if a guy got a girl’s phone number at a coffee shop. Somewhere between the coffee shop and his apartment, he loses the number. When he gets home, to his chagrin, he finds that the number is gone, and he’ll never be able to call the woman of his dreams. However, his roommate quickly says, “Wait a minute. Don’t worry. You’ve got all of the numbers right here on your cell phone… Zero through nine. Therefore, you’ve got all of the numbers required to call her!” Of course, the numbers on the phone are not the man’s problem. Instead, he needs the proper sequence of numbers. In the same way, even if we have amino acids (i.e. the numbers), this doesn’t even begin to explain how these building blocks could be sequenced in the proper order (i.e. the girl’s phone number).
Second, the amino acids need to be perfectly sequenced. To put this in perspective, the misplacement of just one amino acid in just one protein will cause sickle-cell anemia. Therefore, this sequence is highly specified and orderly.
Third, the Miller-Urey experiment didn’t have an accurate understanding of the early Earth’s atmosphere. While the Miller-Urey experiment believed that the early Earth’s atmosphere was filled with ammonia, methane, and hydrogen, and he believed that the atmosphere contained no free oxygen. However, later biologists have shown that this was a false assumption. Meyer writes,
Neutral gases such as carbon dioxide, nitrogen, and water vapor—not methane, ammonia, and hydrogen— predominated in the early atmosphere. Moreover, a number of geochemical studies showed that significant amounts of free oxygen were also present even before the advent of plant life, probably as the result of the photo-dissociation of water vapor.
Dr. David Deamer (biochemist at the University of California) writes,
This optimistic picture began to change in the late 1970s, when it became increasingly clear that the early atmosphere was probably volcanic in origin and composition, composed largely of carbon dioxide and nitrogen rather than the mixture of reducing gases assumed by the Miller-Urey model. Carbon dioxide does not support the rich array of synthetic pathways leading to possible monomers.
Jon Cohen (in the journal Science) explains,
Today, Arrhenius and many other researchers dismiss the experiment itself because they contend that the early atmosphere looked nothing like the Miller-Urey simulation. Basically, Miller and Urey relied on a ‘reducing’ atmosphere, a condition in which molecules are fat with hydrogen atoms. As Miller showed later, he could not make organics in an ‘oxidizing’ atmosphere.
James Cleaves writes,
Instead, evidence strongly suggested that neutral gases such as carbon dioxide, nitrogen, and water vapor—not methane, ammonia, and hydrogen—predominated in the early atmosphere.
For these reasons, the Stanley-Miller experiment doesn’t really offer a solution to the origin of life. Even if the experiment gave us amino acids (which is dubious), this still wouldn’t explain life’s origin.
 We can also point out that meteors sometimes contain amino acids, as well. For instance, the Murchison meteorite contained small amounts of guanine, adenine, and uracil; however, no cytosine. These also contained less than 15 parts per million. However, we can also point out that some of these meteors with amino acids are actually returning from the early Earth. Rana, Fazale, and Hugh Ross. Origins of Life: Biblical and Evolutionary Models Face off. Colorado Springs, CO: NavPress, 2004. 95-96.
 Davies, P. C. W. The Eerie Silence: Renewing Our Search for Alien Intelligence. Boston: Houghton Mifflin Harcourt, 2010. 30.
 I owe this illustration to Dr. Stephen Meyer—though I’ve slightly altered it. Meyer, Stephen C. Signature in the Cell: DNA and the Evidence for Intelligent Design. New York: HarperOne, 2009. 105.
 Meyer, Stephen C. Signature in the Cell: DNA and the Evidence for Intelligent Design. New York: HarperOne, 2009. 224.
 Deamer, David W. “The First Living Systems: a Bioenergetic Perspective,” Microbiology & Molecular Biology Reviews, Vol. 61: 1997. 239.
 Cohen, Jon. “Novel Center Seeks to Add Spark to Origins of Life,” Science, Vol. 270: December 22, 1995. 1925-1926.
 H. James Cleaves, John H. Chalmers. Antonio Lazcano, Stanley L. Miller, & Jeffrey L. Bada, “A Reassessment of Prebiotic Organic Synthesis in Neutral Planetary Atmospheres,” Origin of Life and Evolution of the Biosphere, Vol. 38: 2008. 105-115.