A QUANTUM-THEORETICAL APPROACH TO THE PHENOMENON OF DIRECTED MUTATIONS IN BACTERIA (HYPOTHESIS)

The Darwinian paradigm of biological evolution is based on the indepen dence of genetic variations from selection which occurs afterwards. Ho wever, according to the phenomenon of directed mutations, some genetic variations occur mostly when the conditions favorable for their growt h are created. I propose that the explanation of this phenomenon shoul d not rely on any special 'mechanism' for the appearance of directed m utations, but rather should be based on the principles of quantum theo ry. I consider a physical model of adaptation whereby a polarized phot on, passing through a polarizer, changes its polarization according to the angle of the polarizer. This adaptation occurs by selection of th e 'fitted' polarized state which exists as a component of superpositio n in the initial state of the photon. However, since the same state of the incoming photon should be decomposed differently depending on the angle of the polarizer, in this case the set of variations subjected to selection depends upon the selective conditions themselves. This re veals the crucial difference between this model of adaptation and cano nical Darwinian selection. Based on this analogy, the capacity of a ce ll to grow in particular conditions is considered an observable of the cell; the plating experiments are interpreted as measurement of this observable. The only nontrivial suggestion of the paper states that th e cell, analogously to the polarized photon, may be in a state of supe rposition of eigenfunctions of the operator which represents this obse rvable, and with some probability can appear as a mutant upon the meas urement. Alternative growth conditions correspond to the decomposition of the same state vector into a different superposition, consistent w ith measurement of a different observable and appearance of different mutants. Thus, consistent with the suggested analogy, directed mutatio ns are explained as a result of random choice from the set of outcomes determined by the environment. (C) 1997 Elsevier Science Ireland Ltd.