Earth is a home of various diverse varieties of animals and plants. The natural maintenance of the world is regulated by the equilibrium in number of organisms. Even if a specific unique species become increased , it would affect the whole system. For example , if the number of lions increase in an area it would cause extinction of other organism in the immediate bottom of the food chain . This case happens in case of humans also. If birth rate increases without a regulating death rate , it will leads to a great disaster . The amount of food received per capita would decrease ,causing poverty and malnutrition . This would leads to the extinction of some consumable food (organism) like chicken and goat. A proper maintenance of the population is necessary for the maintenance of equilibrium by the nature .