Influence of aging rate change on mortality curves.

One of the key problems of experimental gerontology is that there is usually some degree of uncertainty in the correct interpretation of experimental or observational data. Namely, it is difficult to decide whether the changes in life span, mortality rate or physiological state are due to the changes in biological age of organisms or to other causes. The analysis of mortality curves, suggested here, can reveal relevant information and may also contribute to discussions on the nature of the aging process. Our models are designed to provide a mathematical and system-theoretical basis to this methodology. The conditions of the validity of the models are simple and their relevancy to reality is discussed. Further, the reliability model suggests an explanation of apparent discrepancy between constant relative decline in physiological functions, often observed during aging, and Gompertzian growth of mortality.