From his experiments, $S.L.$ Miller produced amino acids by mixing the following in a closed flask

$A$ : During evolution the early time period was without ozone layer.
$R$ : Ozone layer absorbs $U.V.$ rays to some extent.

An experiment to prove that organic compounds were the basis of life, was performed by

The first non-cellular form of life could have originated about $. . . . .$ years ago.