A STUDY OF AGING, THERMAL KILLING, AND 

 RADIATION DAMAGE BY INFORMATION THEORY 



Hubert P. Yockey 



Health Physics Division, 

 Oak Ridge National Laboratory, Oak Ridge, Tennessee 



Abstract — The information theoretic formahsm developed in the author's paper in Part I 

 has been applied to the calculation of survival curves. The results have been compared for a 

 variety of organisms ranging from viruses to mammals. The deleterious agent varied in the 

 magnitude of its quantum energy from thermal and chemical energies to several Mev. 



It should be emphasized that this article says very Uttle about models. In general the 

 accepted model of the organism is taken and its behavior is calculated from those features 

 of the model which have the aspects of a communication system. 



In spite of the complexity and variety of the organisms and the range of energy in the lethal 

 agent and without ad hoc assumptions pertaining to models, we were able to account for the 

 main features and some details of the survivorship curves. Many additional experiments will 

 be suggested; some of them have been pointed out and some predictions have been made. 



The idea of the storage and transfer of information and its destruction by deleterious 

 agents seems to link the material discussed. Much of this material may otherwise seem 

 unrelated or only vaguely so. 



I. INTRODUCTION 



The study of the survivorship curve has contributed to the quantification of 

 some essential but otherwise quahtative notions in biology. The effect of 

 various insults such as ionizing radiation, ultraviolet light, temperature, disease, 

 chemicals, and so forth, is very often measured by survivorship of a suitable 

 test organism. On the other hand, the experimenter may be interested in the 

 survival response of a particular organism as a function of maturation, nutrition, 

 strain difference, or the like, and may use some convenient agent as a test 

 stimulus. 



Survivorship does not contain all we feel intuitively is involved in the concepts 

 of 'vigor' or 'fitness' but it does contain much of what can be defined and 

 measured in an unequivocal and operational way that is associated with those 

 ideas. These facts, together with the application in evaluating quantitatively 

 hazards to man, make this subject one of great practical and theoretical 

 interest. 



Information theory is peculiarly well qualified to provide a mathematical 

 treatment of these matters. The survivorship curve is a property of the ensemble 

 of organisms rather than of the individual. It reflects the generalized decay of 

 the organization of a system. The central thesis of this paper is that aging, 

 thennal killing, and radiation damage reflect essentially the same action, namely, 

 the destruction of the information content of the cell. The ideas discussed in 

 the author's previous article in this volume will be applied to the calculation of 



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