RNA-first accounts rely on ribozymes as evidence of catalytic potential, but catalytic efficiencies of ribozymes are limited compared to proteins, raising doubts about whether an RNA-only system could sustain increasing complexity.
Protein-first scenarios highlight peptide thermostability and catalytic diversity, but lack a plausible mechanism for information inheritance without a coding template.
2. Problem of synchronization.
Both models assume sequential emergence, yet the functional interdependence of genetic codes and proteins suggests that partial systems would have limited adaptive value. For example, a rudimentary coding scheme without stable proteins, or proteins without templated replication, would be evolutionarily fragile.
3. Fossil and molecular record ambiguity.
No direct empirical evidence supports the existence of a purely RNA-based or protein-only biosphere. Instead, comparative genomics and proteomics reveal deep co-dependencies---such as ribosomal RNA--protein complexes---that appear to have coexisted from the earliest reconstructable stages of life.
4. Lack of formal dynamical modeling.
Existing narratives remain primarily descriptive, framing origin scenarios in historical terms rather than in dynamic, testable models. They often neglect the feedback processes by which RNA and protein structures could have co-adapted simultaneously under evolutionary pressures.
In short, both RNA-first and protein-first models reduce the complexity of molecular coevolution to a linear sequence, overlooking the possibility that the genetic code and proteins could have emerged in tandem through coupled dynamics. This motivates the need for a framework that captures interdependence, feedback, and emergent synchronization---precisely the domain of Complex Adaptive Systems (CAS).
B. The puzzle of synchronized molecular codes
At the heart of the origin-of-life debate lies a fundamental puzzle: the synchronization of molecular codes. Genetic information and proteins are not merely sequential innovations; they are mutually dependent systems. Genetic codes without proteins lack catalytic power and structural diversity, while proteins without codes lack a mechanism of inheritance and fidelity. Life as we know it depends on the simultaneous existence of both.
Several empirical observations underscore this puzzle:
