Definition
A replicator is an entity that produces copies of itself, and whose copies can in turn produce further copies, with occasional variation. Natural selection acts on replicators because differences in copying success accumulate over generations.
A successful replicator has three properties (Dawkins, The Selfish Gene, topic 2):
- Longevity — how long copies persist before degrading.
- Fecundity — how many copies it makes per unit time.
- Copying-fidelity — how accurately copies preserve the original pattern.
Variation in any of these among rival replicators produces differential survival of replicator lineages — which is to say, evolution.
Why it matters
How it works
Once a replicator exists in a population, copies are made. Each copy is occasionally imperfect — a copying error or mutation. Variants compete with each other for the substrate (DNA, brain space, server capacity) needed to make further copies. Variants that copy more reliably, more abundantly, or more durably come to dominate.
The whole structure of evolution follows from this. No additional ingredient is required — no designer, no purpose, no foresight. Just a copying mechanism with imperfect fidelity, operating in a finite resource environment.