ABSTRACT
Inherent in von Neumann’s view of self-reproduction is a threshold of complication. Once across the threshold, systems can evolve over time into other systems which are far more complex. Prominent biologists have proposed several such thresholds, all involving changes in information transmission between generations. This chapter argues for exactly two thresholds, the first from the RNA world to life based on DNA and protein, and the second from preliterate cultures to civilization based on writing and technologies of measurement and manipulation. Today’s living world was preceded by a less complex world based on RNA, which can operate both as a sequence and as an interactor called a ribozyme. The transition from preliterate culture to our literate technological civilization paralleled the transition from the RNA world to DNA-RNA-protein biology. While both precursor systems were governed by sequences, those sequences were unstable, with poor replication fidelity, and did not allow accumulation of functional novelty. DNA replaced RNA and writing replaced speech for sequence storage, enabling the systems to improve physical stability and replicative fidelity. Protein biocatalysts supplemented ribozymes and technologies of measurement and manipulation supplemented the human phenotype, increasing the power, accuracy, and versatility of each system’s interactors.
