Athel Cornish-Bowden, from CNRS in France, will give a talk about "Life before LUCA".

Abstract

In this seminar I shall present our vision of LUCA and why we think that it is an entity much more recent than the first living systems. This raises the question of what a living system is, and I shall briefly discuss several theories of life: (M,R)-systems (Robert Rosen), autopoiesis (Humberto Maturana and Francisco Varela), chemotons (Tibor Gánti), autocatalytic sets (Freeman Dyson and Stuart Kauffman), and hypercycles (Manfred Eigen and Peter Schuster).

I shall finish by presenting a deterministic computer model of a very simple (M,R)- system that shows that it can maintain a steady state indefinitely and recreate it after a catastrophic collapse. A stochastic version of the model has similar properties, but cannot survive for infinite time. Study of the stochastic system suggests that there is a limiting cell-size below which self-organization is impossible. With reasonable estimates of the kinetic parameters this limit is about 0.01% of the volume of a bacterial cell.