How did life begin?
Answers
Explanation:
Four billion years ago, something started stirring in the primordial soup. A few simple chemicals got together and made biology – the first molecules capable of replicating themselves appeared. We humans are linked by evolution to those early biological molecules. But how did the basic chemicals present on early Earth spontaneously arrange themselves into something resembling life? How did we get DNA? What did the first cells look like? More than half a century after the chemist Stanley Miller proposed his “primordial soup” theory, we still can’t agree about what happened. Some say life began in hot pools near volcanoes, others that it was kick-started by meteorites hitting the sea.
Explanation:
Scientists do not know how life began on Earth, but they do know that the early Earth’s atmosphere was very different from the atmosphere now.
In 1952, Stanley Miller was working with Harold C. Urey designed an experiment to see how complex organic molecules might have formed under the conditions of early Earth. They believed the early Earth atmosphere would have been composed of methane, ammonia, hydrogen and water vapor. They sealed these gases in an airtight container, and then exposed the gases to sparks of electricity to simulate lightning. They continued the lightning for a week, and by the end, a reddish-brown substance had coated the walls of the container. This substance contained 11 of the 20 amino acids used by life on earth. Since Miller and Urey performed this experiment, its results have been confirmed many times by other scientists. Many scientists now believe that the early Earth’s atmosphere was composed of carbon dioxide, nitrogen and water vapor.
The Moller-Urey Experiment
Modern experiments with this mixture of gases produce similar results suggesting that early conditions on Earth produced complex organic molecules that probably became the basis for the development of more complex organisms. However, scientists have not been able to replicate the formation of even simple organisms, or anything that can really replicate itself. There are several theories as to how the amino acids might have made the leap into the complex, self-replicating life we see today.
This animated video from Youtube channel Stated Clearly describes the Miller-Urey Experiment.