Penna Model

In the T = 1 case, one expressed deleterious mutation is enough to trigger death or aging. Positive mutations are excluded from the model because they are considered rare. The study operationalized fitness through survival rate because functional loss affects environmental survival. The model treats genetic death as occurring when active harmful mutations reach the mutation threshold. A bit value of 1 represents a harmful mutation or disease in the model. In the model, each individual has a 32-bit genome with one bit read per year of life. In the original Penna model, a bit value of 1 represents a mutation and a bit value of 0 represents no mutation. The Penna model represents aging through mutation accumulation in age-indexed bit strings. The Penna model imposes a hard maximum lifespan through bit-string length. The study uses the standard asexual Penna aging model to study age-structured mutation accumulation.