THE ARRIVAL OF THE FITTEST - TOWARD A THEORY OF BIOLOGICAL ORGANIZATION

The formal structure of evolutionary theory is based upon the dynamics of alleles, individuals and populations. As such, the theory must ass ume the prior existence of these entities. This existence problem was recognized nearly a century ago, when DeVries (1904, Species and Varie ties: Their Origin by Mutation) stated, ''Natural selection may explai n the survival of the fittest, but it cannot explain the arrival of th e fittest.'' At the heart of the existence problem is determining how biological organizations arise in ontogeny and in phylogeny. We develo p a minimal theory of biological organization based on two abstraction s from chemistry. The theory is formulated using lambda-calculus, whic h provides a natural framework capturing (i) the constructive feature of chemistry, that the collision of molecules generates specific new m olecules, and (ii) chemistry's diversity of equivalence classes, that many different reactants can yield the same stable product. We employ a well-stirred and constrained stochastic flow reactor to explore the generic behavior of large numbers of applicatively interacting lambda- expressions. This constructive dynamical system generates fixed system s of transformation characterized by syntactical and functional invari ances. Organizations are recognized and defined by these syntactical a nd functional regularities. Objects retained within an organization re alize an algebraic structure and possess a grammar which is invariant under the interaction between objects. An organization is self-maintai ning, and is characterized by (i) boundaries established by the invari ances, (ii) strong self-repair capabilities responsible for a robustne ss to perturbation, and (iii) a center, defined as the smallest kineti cally persistent and self-maintaining generator set of the algebra. Im position of different boundary conditions on the stochastic flow react or generates different levels of organization, and a diversity of orga nizations within each level. Level 0 is defined by self-copying object s or simple ensembles of copying objects. Level 1 denotes a new object class, whose objects are self-maintaining organizations made of Level 0 objects, and Level 2 is defined by self-maintaining metaorganizatio ns composed of Level 1 organizations. These results invite analogy to the history of life, that is, to the progression from self-replication to self-maintaining procaryotic organizations to ultimately yield sel f-maintaining eucaryotic organizations. In our system self-maintaining organizations arise as a generic consequence of two features of chemi stry, without appeal to natural selection. We hold these findings as c alling for increased attention to the structural basis of biological o rder.