Positive mutations and mutation-dependent Verhulst factor in Penna ageing model

TL;DR

This paper enhances the Penna ageing model by incorporating beneficial mutations and a mutation-dependent Verhulst factor, leading to improved species fitness, punctuated equilibrium, and a mortality maximum in old age.

Contribution

It introduces back mutations and a mutation-dependent competition factor into the Penna model, providing a more realistic simulation of biological ageing.

Findings

Improved species fitness over long time scales.

Observation of punctuated equilibrium.

Mortality maximum for the oldest individuals.

Abstract

We twice modify the Penna model for biological ageing. First we introduce back (good) mutations and a memory for them into the model. It allows us to observe an improvement of the species fitness over long time scales as well as punctuated equilibrium. Second we adopt a food/space competition factor that depends on the number of accumulated mutations in the individuals genomes, and get rid of the fixed limiting number of allowed mutations. Besides reproducing the main results of the standard model, we also observe a mortality maximum for the oldest old.