The authors have tried to summarize the biophysical causes, laws and consequences of the processes of ageing. After surveying the development which Man's life span and senescence have undergone in the course of evolution as well as the underlying causes, they demonstrate the influence which the size of the brain has on the life span. A correlation can be shown to exist between brain weight, body weight, metabolic rate, body temperature and life span. Furthermore, an interrelationship between the amount of information available and ageing was not only observed at the cellular level, but also studied in more complex structures. The authors point that that the increase in entropy is linked with the ageing process and that the differences in the capacity of the nervous system (which are equivalent to a given difference in entropy) are accompanied by the same alteration of the live span as if this difference in entropy resulted from deviations in the metabolic processes.