Fig. 1.

A binary soup and the tree of prelife. (A) Prebiotic chemistry produces activated monomers, 0* and 1*, which form random polymers. Activated monomers can become deactivated, 0* → 0 and 1* → 1 or attach to the end of strings, for example, 00 + 1* → 001. We assume that all strings grow only in one direction. Therefore, each string has one immediate precursor and two immediate followers. (B) In the tree of prelife, each sequence has exactly one production lineage. The arrows indicate all of the chemical reactions of prelife up to length n = 4.