Formation of the earth and its early crust and atmosphere, evolution of the biological molecules necessary for life, and evolution of systems of chemical reactions needed to produce the first living cells. These processes are believed to have occurred about 1 billion years before biological evolution. Compare biological evolution.

the hypothetical process by which the chemicals necessary for life emerged on the primitive earth.

The theory that life arose from non-living matter in accord with the ordinary laws of nature; “mud to life.