Date: May 2007
What is a heterotrophic hypothesis of evolution?
The heterotrophic hypothesis, also known as the Haldane-Oparin hypothesis
after two scientists who independently proposed it, posits that life
(organic molecules) could have formed from inorganic molecules. In other
words, life could have formed without requiring a 'divine nudge' and without
having to come from another planet. Much research has been conducted to
explain how (and if) life could spontaneously form. The general theme is
that components of earth's atmosphere could form into complex organic
molecules, which could then assemble into more complex groupings, which
eventually would become life.
One famous experiment by Stanley Miller and Harold Urey used water vapor,
methane, hydrogen, and ammonia (along with an electrical spark) to show that
organic molecules (e.g. amino acids) could form spontaneously. However,
scientists no longer think the Earth's atmosphere resembled the Miller-Urey
composition. Subsequent experiments have shown a rich variety of organic
compounds can form from inorganic carbon sources in various types of
atmospheres. Also, the role of volcanoes, instead of lightning, appears to
be central to the story. The exact composition of Earth's atmosphere remains
a subject of research, but the concept that complex molecules can
spontaneously form seems well supported.
Hope this helps,
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Update: June 2012