All living populations possess a tendency for growth. Simultaneously, these populations encounter limitations to that potential. Some factors affecting human population growth (and other organisms' population growth) include predation, disease, scarcity of vital resources, natural disasters and an inimical environment.
Limiting factors include a low food supply and lack of space. Limiting factors can lower birth rates, increase death rates, or lead to emigration. When organisms face limiting factors, they show logistic growth (S-shaped curve, curve B: Figure below).
