It is quite unbelievable to believe that this world at some point had only two people who inhabited planet earth. But surprisingly, the population today has greatly grown. In 2011 the worlds’ population was estimated to be seven billion. Therefore, this essay will discuss the three components of population change and also show the component which is important in Zambia from 1964 to date. Firstly first, key terms population and population change will be defined and the main body will discuss the three major components of population change which are birth rate, dearth rate and migration, then the conclusion will be drawn.
Population is a group of people living in a particular geographical area. Haggett (1983) simply defines population as a collection of individuals. On the other hand, Ronald (2003) defines population change as the rate at which the population is increasing or decreasing at a given time. In other words, population change simply refers to the difference between the sizes of the population from the beginning to the end of a certain time period.Population has been changing from time to time hence the introduction of demography and statistics to the study of populations. Demography encompasses the study of populations in terms of size, structure, distribution and spatial/temporal changes in the populations in response to birth, death, migration and ageing. Meanwhile statistics refers to the study and practice of collecting data that has a geographic or areal dimension such as census or demographicdata (Dickinson, 1973).
Birth rate is the total number of live births per 1000 in a population in a year or period. The fertility rate in a country refers simply to the number of children born. This is different from the fecundity rate, which is the number of children who could be born in a given society. In other words, fecundity is the biological capacity of humans to produce children. For a woman, this is generally the time frame between her early teens and her mid-forties. For men, this window is longer, but factors like sperm count diminish as a man ages. The fecundity rate is greater than the fertility rate in most cases.Birth rates vary by society for a number of reasons, including personal choice like desire for large families, preference for male child and joint family system. In addition, poverty levels are another contributing factor to birth rate where poor people have to spend less on the upbringing of their children. Besides, the children supplement the family income by engaging themselves in some odd jobs at an early age. Apart from that, lack of access to contraception and knowledge of family planning is another factor leading to birth rate. Others include, maternal and infant care and availability of nutrition all impact the birth rate in a society.Another component of population change is death rate sometimes called mortality rate which refers to the occurrence or frequency of deaths in a population at a given time. Mortality data can be disaggregated by sex, age and residence (rural or urban). Mortality is a very important concept in determining population change. Porta (2014) Death is the end of life, a permanent cessation of all vital functions of the body. A death can only occur after a live birth. Any death before a live birth is referred to as foetal death. Foetal Death- a death prior to the complete expulsion or extraction of a product of conception from its mother regardless of the duration of pregnancy. This is evidenced by lack of breathing, heartbeat, and muscle movements. Dying refers to the body's preparation for death, which may be very short in the case of accidental death, or can last weeks or months in some patients such as those with cancer (Porta, 2014).
Everitt (2006), just as when babies are born, when members of a society die it changes the population. This might be a bit morbid to think about, but scientists refer to this as the mortality rate, which is simply the measure of the number of deaths in a particular population scaled to the size of that population per unit of time that occur in a society. Mortality rate is typically expressed in units of deaths per year. In the United States, for example, the death rate is 8/1000 people.
The major types of mortality or death rate these include maternal mortality rate infant mortality rate refers to the number of deaths among infants aged below one year per thousand (1,000) live births per year. Halley (2010), Child Mortality Rate refers to the number of deaths among children aged between exact age one and five yearsper thousand (1,000) live births per year. Under Five Mortality Rate refers to the number of deaths among children aged below five years per thousand (1,000) live births per year. Therefore, the under-five rate constitutes both the infant and child mortality. Maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and size of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes (Graham, Brass, Snow, 1989).
Severe poverty is the root cause of the high mortality rates in developing countries among them is Zambia. Poverty results in malnutrition, which causes many deaths especially to children under five years. Not only that, routine vaccination is often unavailable for both children and adults and also basic clinic care is in short supply (Porta, 2014). Hence, poverty creates a fertile environment for infectious and parasitic diseases. In addition, it leads to inadequate education. As a result of deficient education, especially females is closely correlated with poor health thus leading to high death rate.Furthermore, another component of population change is migration which simply means a form of spatial or geographic mobility between one geographic unit and another involving permanent change of residence. In other wordsmigration refers to movement; it's the flow or circulation of people in societies. There are two kinds of migration: emigration and immigration. Emigration means to leave one's own country for another. Immigration means to enter into a country other than one's own (Haggett, 1983).
Migration is the way to move from one place to another in order to live and work. People usually move from their home to another city, state or country to search for a job, shelter, or some other reasons. Rural to urban migration has increased because people decide to migrate to have a better life, be employed in companies and industries. In summary reasons as to why people migrate can be categorised in either pull or push factors. Lee (1966), Pull factors are those that attract people to leave a particular area to another for example higher incomes, lower taxes, better weather or climate, better availability of employment, better medical facilities, better education facilities, and better behaviour among people, family reasons, political stability, religious tolerance, relative freedom, and national prestige.
On the other hand, push factors are responsible for making people leave the place where they are for another place. They are conditions in the place of origin which are perceived by migrants as detrimental to their well-being or economic security. Examples of push factors include high unemployment and political persecution. In rural areas, often on small family farms, it is difficult to improve one‘s standard of living beyond basic sustenance. Farm living is dependent on unpredictable environmental conditions, and in times of drought, flood or pestilence, survival becomes extremely problematic. Persecution may be political or fear of witch craft (ibid).
From the above points it can be noted that in Zambia the one which is important among the three is birth rate. The Zambian population from 1964 to date has witnessed rise in the population for example, In 1990 it was at 7,759, 167. In 2000 it stood at 10, 285, 631. According to the 2010 census Zambia’s total population is over 13 ,092 ,666. Among the reasons for this could be early marriages, high poverty levels, high infant mortality rate and desire for large families.

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