The evolution of replicators

Replicators of interest in chemistry, biology and culture are briefly surve yed from a conceptual point of view Systems with limited heredity have only a limited evolutionary potential because the number of available types is too low Chemical cycles, such as the formose reaction, are holistic replica tors since replication is not based on the successive addition of modules. Replicator networks consisting of catalytic molecules (such as reflexively autocatalytic sets of proteins, or reproducing lipid vesicles) are hypothet ical ensemble replicators, and their functioning rests on attractors of the ir dynamics. Ensemble replicators suffer from the paradox of specificity: w hile their abstract feasibility seems to require a high number of molecular types, the harmful effect of side reactions calls for a small system size. No satisfactory solution to this problem is known. Phenotypic replicators do not pass on their genotypes, only some aspects of the phenotype are tran smitted. Phenotypic replicators with limited heredity include genetic membr anes: prions and simple memetic systems. Memes in human culture are unlimit ed hereditary, phenotypic replicators, based on language. The typical path of evolution goes from limited to unlimited heredity, and from attractor-ba sed to modular (digital) replicators.