Summarize the main points in the reading and explain how the lecture casts doubt on the ideas.

According to the passage, Miller and Urey tried to simulate the primitive Earth's condition in lab by connecting a half water-filled flask to another which contained electrodes for inducing electrical charges. Then after introducing electrical shocks to the containment of the flasks they realized that some amino acids that are basic structures of living organisms formed in the water flask. They concluded that the primitive Earth's conditions could reasonably lead to first biologic blocks. In the lecture, however, some points were underlined that cast doubt to this conclusion.

First, the simulated atmosphere in the experiment was exaggerated because the early climates of Earth might not produce such vigorous electrical charges continuously as Miller and Urey did in their experiment. Second, the composition of air in the flask was not the same as the gas mixture of atmosphere in early Earth era. An example is the oxygen that was consumed in Miller-Urey experiment. And the third thing is that amino acids can survive harsh conditions and it is possible that they had existed on Earth already or brought to it by comets and asteroids.

In conclusion, their experiments have some flaws and moreover, cannot explain that how the first living unit comes to life.
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