#6 Miller-Urey Experiment

Great excitement was generated by an experiment performed in 1953 by Stanley Miller and Harold Urey.  They set up an apparatus containing methane, ammonia and hydrogen gases with water vapour to represent the hypothetical early Earth atmosphere and passed electric sparks through it to simulate lightning strikes.  In this reducing atmosphere, the heavy energy input breaks bonds in the gases, and upon cooling bonds reform giving new carbon products.  The broken bonds reassociate in a random way such that many different molecules are produced.  The most abundant product was tar, but there were also two simple amino acids, glycine and alanine in small quantities.  (The amino acid alanine has the formula: CH3CH(NH2)COOH).

Robert Shapiro alludes to his own experiments in which he heated various combinations of organic chemicals together as resulting in a dark, sticky tar.  He had hoped to produce the chemistry of life, but ended up with what he describes as a “gunky mess” (Shapiro 1986, page 206).  Tar is an organic material with excessive bonding.  It is a dead organic material that may originate from life, but it is not helpful to a living organism or as a starting point for life.

Shapiro gives a very good account of the experiments to discover the origin of life that have been conducted over 50 years of the 20th century.  However, he concludes that;

“The very best Miller-Urey chemistry, as we have seen, does not take us very far along the path to a living organism.  A mixture of simple chemicals, even one enriched in a few amino acids, no more resembles a bacterium than a small pile of real and nonsense words, each written on an individual scrap of paper, resembles the complete works of Shakespeare.”  (Shapiro 1986, page 116).