The experimental investigation of life's origin commenced in earnest more than a half-century ago with the pioneering work of Miller, who synthesized many of life's molecular building blocks under plausible prebiotic conditions. Despite an initial euphoric sense that the origin mystery would soon be solved, scientists quickly realized that the transition from a geochemical to a biochemical world would not easily be deduced by the scientific method.

The great challenge of origins research lies in replicating in a laboratory setting the extraordinary increase in complexity that is required to evolve from isolated molecules to a living cell. The principal objective of this review is to describe some of the efforts by origin-of-life researchers to induce such increases in complexity. A unifying theme of these studies, and hence a useful organizing framework for this review, is the principle of emergence – the natural process by which complexity arises.

Emergence as a unifying concept in origins research

The origin of life may be modeled as a sequence of so-called “emergent” events, each of which added new structure and chemical complexity to the prebiotic Earth. Observations of numerous everyday phenomena reveal that new patterns commonly emerge when energy flows through a collection of many interacting particles.