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Name: Kaitlin
Status: student
Grade: 9-12
Location: NY
Date: May 2007

Question:
What is a heterotrophic hypothesis of evolution?



Replies:
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,

Burr



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