Tuesday, November 26, 2013

The Miller Experiment About Life Began

When scientists set about solving the problem of how life began, they first looked for a source of the chemicals out of which living things are made. They devised an experiment, that under the primitive Earth’s conditions, the complex chemicals of life could form from simple, inorganic precursors. In 1953, Stanley Miller tested the theory:

  1.  Miller essentially put methane, or natural gas, ammonia, hydrogen gas, and water vapour into a beaker, based on the theory of what the primordial atmosphere would have looked like.
  2. Next, he simply put an electric charge through that mixture to simulate lightning going through an early atmosphere.
  3. After sitting around for a couple of days, all of a sudden there was this brown ‘soup’ all over the reaction vessel.
  4. On analysis of the vessel, rather than only having methane and ammonia, he actually had amino acids, which are the building blocks of proteins, fatty acids and other complex biological molecules.
  5. So the chemistry that Miller was discovering in this wonderful experiment was not some improbable chemistry, but a chemistry that is widely distributed throughout our solar system.
  6. The experiment used water (H2O), methane (CH4), ammonia (NH3) and hydrogen (H2).
  7. The chemicals were all sealed inside a sterile array of glass tubes and flasks connected together in a loop, with one flask half-full of liquid water and another flask containing a pair of electrodes.
  8. The liquid water was heated to induce evaporation, sparks were fired between the electrodes to simulate lightning through the atmosphere and water vapour, and then the atmosphere was cooled again so that the water could condense and trickle back into the first flask in a continuous cycle.
  9. The chemicals found in the 'soup' of Miller's experiment were found to be accumulated in lakes and ponds, where they changed, combined, and re-combined in millions of different ways over vast periods of time.
  10. Complexity increased until cell like structures appeared with the first major characteristics of life: the ability to reproduce and grow, feeding on materials from the ‘primordial soup’ in which they formed.