Physical Problems of the Origin of Natural Controls

Abstract

The physical embodiments of a control element or system are called non-integrable constraints. A constraint, in general, requires an alternative description to the microscopic description of the system. This alternative description selectively ignores detail which corresponds in the physical system to some form of dissipation process which gives rise to the new coordinations of the constraint and a simplified collective behavior we recognize as function. The origin of such control constraints must begin with low selectivity and imprecise function and gradually sharpen up to high specificity and narrow, precise function. The central physical problem is to understand the necessary conditions for primitive molecular control elements to evolve complexity of coordination and simplicity of function.

The problem of the origln of control is quite distinct from the problem of the operation of a well-defined control system. The basic physical distinction is that the operation of a control system assumes the existence of organized structures which are treated as boundary conditions or equations of constraint, whereas the origin problem must account for the establishment of these boundary conditions and constraints from the laws of motion starting from a relatively disorganized collection of matter. This distinction between the origin and operation of controls holds at all evolutionary levels. In fact it is the origin of these levels of hierarchical control which is the most difficult problem of evolutionary theory. However in this brief discussion we will emphasize only the simplest molecular level which was presumably the level at which life itself first originated.

The operation of controls in classical or statistical organizations or devices is now a welldeveloped mathematical theory, which does not directly concern us here (see, e.g., (1)). The basic idea of control theory is to produce a desirable or predetermined behavior in a physical system by imposing additional forces or constraints. The corresponding mathematical problem is either that of optimizing the control strategy under given constraints, or in determining the stability of the system with respect to the control variables or to outside perturbations. Most of these problems have their motivation in man’s attempt to artificially control inanimate matter, other living systems, or to outwit his fellow man.

The problem I wish to discuss is the origin of controls that arise naturally, that is, without the intervention of man’s intellect. These are the controls characteristic of living matter, and are embodied at the most fundamental level in copalymer moleeules such as polypeptides and polynucleotides. Specifically, I would like to know to what extent the laws of physics can account for the spontaneous origin of molecular control systems.