The first-ever analysis of some of chemist Stanley Miller's old samples has revealed another way that important molecules could have formed on early earth.
The study discovered a path from simple to complex compounds amid earth's prebiotic soup.
Stanley Miller was a chemist whose landmark experiment, published in 1953, showed how some of the molecules of life could have formed on a young earth. He left behind boxes of experimental samples that he never analysed.
More than four billion years ago, amino acids could have been attached together, forming peptides.
These peptides ultimately may have led to the proteins and enzymes necessary for life's biochemistry, as we know it.
In the new study, scientists analysed samples from an experiment Miller performed in 1958.
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To the reaction flask, Miller added a chemical that at the time wasn't widely thought to have been available on early earth.
The reaction had successfully formed peptides, the new study found. It also successfully replicated the experiment and explained why the reaction works.
"It was clear that the results from this old experiment weren't some sort of artefact. They were real," said Jeffrey Bada, professor of marine chemistry at University of California, San Diego in the US.
The study was published online in the journal Angewandte Chemie International Edition.