Human population increases and decreases

There's so many people in the Earth we can reach to nine million by about the year of 2040. These are the factors affecting human population size which is birth rate and Death rate . The birth rate is the number of babies born in a year for every 1000 people .A high birth rate may be caused by:
            - Early marrieges
            - Lack of knowledge of birth control


A high birth rate and a low death rate will result in an increase in the size of a population. A high death rate may be caused by :
                 - Diseases
                 - Famine
                 - natural disasters


The death rate is the number of people dying in a year for 1000 people. A high death rate and a low birth rate will result in a decrease in the size of a population.

The human population may be described by its population density .When the population in a place grows , the population density of that place increase.


Population density is affected by Human migration which occurs in the form of Immigration and Emigration.People who migrate are called migrants . 
Immigration takes place when people move into a country permanently. People who Immigrate are called Immigrants . Emigration takes place when people move out of the country permanently. People who emigrate are called emigrants. 


                    




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