Astrobiologists Loren Williams and John Peters have collaborated to produce a review article in the current issue of Astrobiology in which they treat the origin of life as a retracing of the transition from prebiotic to biotic, a problem which can be addressed from both the bottom up and the top down.

The Bottom-Up approach applies fundamental principles of chemistry, organic synthesis, transition metal chemistry, and molecular assembly in experimental systems that mimic the chemical conditions of prebiotic Earth. Investigators strive to understand and recapitulate steps in the origin of life, including the formation of precursors, building blocks, polymers, macromolecular assemblies, and catalytic functions.

Properties of extant life are used in “Top-Down” approaches to infer molecules, pathways, structures, and assemblies of ancient life. The premise is that some extant metabolites, biochemical systems such as translation, and metalloproteins are linked by sometimes indistinct, but ultimately traceable, threads to early biotic and prebiotic chemical systems.