A jockey feeds a carrot to his horse first thing in every morning. The horse now "neighs" every morning when it sees the jockey. Neighing is a(n) _*learned*_ response to the carrot provided by the jockey, an _*external*_ stimulus.
The Miller–Urey experiment (or Miller experiment) was a chemical experiment that simulated the conditions thought at the time to be present on the early Earth, and tested the chemical origin of life under those conditions. The experiment supported Alexander Oparin's and J. B. S.
