NONEQUILIBRIUM STEADY STATES IN MODELS OF PREBIOTIC EVOLUTION

Abstract:

We report computational results from a model for prebiotic evolution.
The model is schematic, but contains a correct description of the
basic statistical problem associated with understanding how the initiation of
life can occur given the strong entropic barriers (sometimes
known as 'Eigen's paradox' and appearing in experiments as the 'tar problem').

The model is similar to one of the models
introduced years ago by Kauffman and coworkers. The important innovation
which we introduce is imposition of the requirement that, to qualify
as a lifelike dynamical chemical system, the system must not be in
chemical equilibrium. That constraint turns out to have major qualitative
effects on the conclusions. In particular, very sparse chemical networks
turn out to be the most favorable ones for generating autocatalytic
nonequilibrium states. This suggests qualitatively that deserts might be
better than ponds for initiating life. Some details of the models and
simulations will be described, including recent results in which we
introduce spatial diffusion and a proxy for temperature into the description of
the model chemistry. Results on growth rates, convergence and the
overall probability of generation of lifelike states as a function of
parameters of the chemical network model will be presented.