Logistic growth occurs because of natural selection. Here nature selects the filter ( Survival of the fittest). Nature has resource to support maximum number of people (Carrying Capacity (K)) beyond which resources won’t support them due to their lock. This explain that log phase follows phase of acceleration. So we get sigmoid curve.
This growth is Verhulst-pearl Logistic Growth
N = Population density at time
K = Carrying capacity
r = Intrinsic rate of natural increase
