Simplify the following text for a Grade 14 native English-speaking person.
Original: A graduate student , Stanley Miller , and his professor , Harold Urey , performed an experiment that demonstrated how organic molecules could have spontaneously formed from inorganic precursors , under conditions like those posited by the Oparin-Haldane Hypothesis .
Simplified: In 1953 a graduate student , Stanley Miller , and his professor , Harold Urey , performed an experiment that showed how organic molecules could have formed on early Earth from inorganic precursors .