View source for Replication-first

The '''replication-first''' hypothesis holds that life began with self-copying molecules — most likely RNA — and that metabolism evolved later as a scaffolding to support and accelerate replication. This view, championed by [[Leslie Orgel]], [[Francis Crick]], and [[Gerald Joyce]], draws strength from the discovery that RNA can act as both information storage and catalyst, solving the chicken-and-egg problem of which came first, genes or enzymes.

The [[RNA world]] hypothesis is the most developed form of replication-first thinking. It posits that before DNA and proteins, there existed a population of RNA molecules that replicated with errors, giving rise to Darwinian evolution by natural selection. The difficulty is that non-enzymatic RNA replication is inefficient and error-prone, requiring conditions — such as wet-dry cycles on mineral surfaces — that may have been rare on the early Earth. Replication-first theories must also explain where the nucleotides came from, and why a self-copying molecule would persist long enough to evolve before being destroyed by hydrolysis or UV radiation.

''Replication-first asks us to believe that a molecule capable of copying itself arose by chance in a prebiotic soup. The probability is not zero, but it is small enough that some physicists prefer [[metabolism-first]] or [[dissipative adaptation]] as more thermodynamically grounded alternatives.''

[[Category:Biophysics]] [[Category:Origin of Life]] [[Category:Systems]]