Miller and Urey Experiment
In 1953, Stanley L. Miller and Harold C. Urey attempted to prove that the simplest of chemicals could be capable of forming life on earth in what is known as the Miller-Urey experiment. By replicating the conditions of the early atmosphere of Earth, Miller and Urey were able to show that different organic molecules could be naturally and spontaneously formed.
To do this experiment, Miller and Urey created a device that contained the basic molecules that could have been on Earths atmosphere up to 4 billion years ago, and situated it above a container with water. The basic molecules were methane, hydrogen, and ammonia, and the water symbolized the early ocean. To simulate lightning and the amount of energy needed to perform the experiment, electrodes were sent into the device containing the mixture of gases.
After allowing the experiment to run for approximately one week and letting it cool, Miller and Urey found that more complex organic compounds had formed- urea, organic acids, simple sugars, and amino acids. This helps to prove that chemical reactions that occurred naturally helped form the first organic molecules. Although the experiment showed that the basic building blocks of life could have formed spontaneously, it did not provide evidence for a full biochemical system.
To do this experiment, Miller and Urey created a device that contained the basic molecules that could have been on Earths atmosphere up to 4 billion years ago, and situated it above a container with water. The basic molecules were methane, hydrogen, and ammonia, and the water symbolized the early ocean. To simulate lightning and the amount of energy needed to perform the experiment, electrodes were sent into the device containing the mixture of gases.
After allowing the experiment to run for approximately one week and letting it cool, Miller and Urey found that more complex organic compounds had formed- urea, organic acids, simple sugars, and amino acids. This helps to prove that chemical reactions that occurred naturally helped form the first organic molecules. Although the experiment showed that the basic building blocks of life could have formed spontaneously, it did not provide evidence for a full biochemical system.
This short video provides an animation of the processes of the Miller-Urey experiment conducted by Stanley L. Miller and Harold C. Urey.
Criticisms of the Miller-Urey experiment
The Miller-Urey experiment gave rise to other experiments that agreed and disagreed with the findings. These other experiments led to many criticisms of the Miller-Urey experiment:
- It was thought by some scientists that the amount of gases in Earth's atmosphere that Miller and Urey were trying to simulate were actually much less than what they thought at the time of their experiment.
- The amount of energy provided by the electrodes representing lightning during the experiment have been criticized to be far stronger than the amount of energy that would have actually been present.
- Some things have been seen that could lead to the idea of an origin of life outside of Earth.
- Early Earth was hit by large amount of comets, which possibly could have had a huge storage of complex organic molecules.