Abstract: One of the puzzles in the origin of life on Earth is the emergence of complex chemical organization on the prebiotic Earth. While autocatalytic sets of chemicals can plausibly arise on the prebiotic Earth, we do not quite understand how these might have established a significant presence, and further, evolved into complex chemical organizations that were likely precursors of living cells. In the talk I will review some of the issues in the dynamics of autocatalytic sets and describe a mathematical model that suggests a mechanism for their dominance and evolution.
Autocatalytic reaction systems are known to exhibit bistability wherein one attractor of the population dynamics has insignificant levels of the catalysts while the other attractor has catalysts at high levels and functions as an autocatalytic set. The model considers a situation wherein such artificial chemistries reside within protocells and the enclosure forming molecules are part of the autocatalytic set. Starting from the initial condition where the protocell is in the non-autocatalytic attractor, it is found that stochastic fluctuations within the protocell allow the chance production of catalyst molecules and a transition to the autocatalytic attractor. Further, the protocells in the autocatalytic state grow at a higher rate compared to those in which the catalyst is absent. The system therefore spontaneously develops a primitive selection mechanism wherein the autocatalytic state gets fixed in a population of protocells. Nested autocatalytic sets produce multistability, which can be exploited to iterate the above process and produce a punctuated sequence of increasingly complex chemical organizations.