Life on Earth may have started with a bang. (credit: Don Davis/NASA)
There aren’t a lot of individual experiments that have ended up being staples of high school textbooks, but Stanley Miller and Harold Urey did one of them. Miller and Urey are the people who sealed up a mixture of gases meant to model the Earth’s early atmosphere and jolted the gas with some sparks. What emerged was a complex mix of chemicals that included amino acids, the building blocks of proteins.
It was a seminal experiment in that it gave researchers one of the first avenues to approach the origin of life experimentally, but its relevance to the actual origin of life has faded as the research it inspired began to refine our ideas.

A French-Czech team of researchers decided to give it another look, using a source of energy that Miller and Urey hadn’t considered: the impact of a body arriving from space.

The result? The production of all four of the bases found in RNA, a close chemical cousin to DNA and equally essential to life.
Conceptual shifts
There are two reasons that the Miller-Urey experiment gradually fell out of favor.

The first is conceptual.

At the time, people focused on life’s dizzying web of chemical reactions, almost all of which are catalyzed by proteins, so it was hard to envision life without proteins.

The formation of amino acids could enable the formation of proteins and thus seemed to provide an obvious route to a primitive biochemistry.

Genetic material could be added later.
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