Abstract :
The World3 population sector is analyzed, not to criticize the underlying assumptions, but a) to elucidate the inner working and general behavioral properties of the submodel and b) to illustrate the use of simple methods of understanding complicated models. If ample food is available, population tends towards exponential growth owing to positive feedback within the sector itself, whereas negative feedback predominates if food is scarce. The model´s carrying capacity for population is primarily determined by food production, equilibrium being mainly achieved by starvation. If income and/or pollution is high, however, equilibrium conditions may be rather different. The effect of introducing age distribution is only slight.
