metabolismfirst

Metabolismfirst, also written metabolism-first, is a term used in origin-of-life research to describe a family of hypotheses that propose metabolic networks—self-sustaining sets of chemical reactions capable of energy transduction and substrate turnover—emerged before informational macromolecules such as RNA or DNA. In these models, life begins with metabolism-like chemistry that can maintain and reproduce networks, with genetic replication arising later to stabilize heredity.

Historically associated with Günter Wächtershäuser’s iron-sulfur world hypothesis, metabolism-first emphasizes mineral-catalyzed reactions on surfaces, particularly at hydrothermal vent environments, where iron-sulfur chemistry could drive energy-rich cycles. Variants include alkaline hydrothermal-vent models where natural proton gradients power polymer formation, and surface-metabolism proposals where reactions occur on mineral surfaces before membranes and genes. Autocatalytic networks, conceptualized by Stuart Kauffman, are sometimes cited as a mechanism for self-sustaining chemistry.

Key ideas include autocatalysis and network topology enabling growth and maintenance; the emergence of protometabolic cycles that funnel geochemical energy into constructive synthesis; and gradual compartmentalization that ultimately supports Darwinian evolution.

Criticisms concern whether prebiotic chemistry could reliably produce durable, evolving metabolic networks and how such networks would transition to genetic systems capable of information storage and heredity. Critics argue that while metabolism-first can explain energy capture and complexity, it struggles to account for accurate replication and inheritance without linking to a genetic polymer.

Today metabolismfirst remains a prominent but debated strand of origin-of-life theory, often contrasted with gene-first hypotheses such as the RNA world. Some researchers seek integrative scenarios in which metabolic networks and information-bearing molecules coemerge, aiming to bridge chemistry, catalysis, and heredity.