Effect of time slowing in biological ageing

Abstract

The Penna model which accounts for genetic death was applied in computer simulations of population growth and ageing. In this paper we assume a biological time scale in which time runs faster for younger individuals than for the old ones. This means that we read out the genome's fraction, later used in the life game, at a greater pace of 4 bits per evolution time step for very young individuals, and 1 bit per iteration for the oldest. This new mechanism, likely to be present in nature, yields some new and interesting aspects concerning the final population characteristics. We found that the partial distribution function p ( m ) of ‘bad’ mutations m , for groups of same age a , is altered as compared with the standard Penna model. The tendency is that a young population becomes healthier, that is with a smaller portion of youngsters with many bad mutations. This effect is still present yet less pronounced for older individuals. We expect that the main findings may be statistically significant to be observed in real populations. For a typical set of model parameters, calculations on population of the order of one million items requires about 100 MB memory and execution takes a couple of hours for 2 or 3 thousand iterations on the HP EXEMPLAR machine.