The whole universe is going through an unprecedentedly fast demographic adjustment. The human population has increased tremendously since the year 1950. The human population today is approximated to be at four billion. With all the adjustments taking place at the moment in the universe, it is expected that there will be numerous changes in both the developing and the developed parts of the world. In the coming centuries, the developed world is likely to stagnate or decline in terms of development (Ehrlich 25). On the other hand, the least developed countries are expected to develop more within the coming decades. Apart from development there also other demographic elements experiencing immense change. The fertility rate of women, for example, is dropping rapidly while that of life expectancy is rising fast. The various trends in mortality and fertility have led to an increased fertility for the young generation in the developing nations and also an increase of the same for the older people in developed countries (Livi-Bacci and Blackwell). This paper focuses on the trends in human population growth, human fertility and mortality, and age factors in the experienced transformation. Change is inevitable and the human population is experiencing it and will continue experiencing it in the coming decades all in terms of fertility and mortality in relation to the population size.
The population of the world hit one billion in 1800. Before that, the population growth was so sluggish and uneven. Thereafter the growth rate of the human population started growing slowly and steadily and hit 2.5 billion in the year 1950 (United Nations 1962, 1973, 2007). Growth rates still increased in the following years. The human population grew so fast as the twentieth century was coming to an end. By 2005 the human population of the entire world hit 6.5 billion which was more than a double of the previously recorded population in 1950 (United Nations 1962, 1973, 2007). According to researchers on the human population, the world population is expected to be ten times what it was in 1800 by 2070.
All these changes in the rapid growth of the human population can be summarized in a single term “demographic transition”. The rapid growth in human population experienced demographic transition occurs when there is a decrease in both the birth rate and the death rate (Butler). One major characteristic of a demographic transition is the transformation of the agricultural sector into an industrial one. This transition normally occurs in two phases. The first phase normally entails a high rate in the growth levels mainly because there is a decrease in mortality rate. In the subsequent phase, the growth rate drops due to the decrease in the birthrate. The entire transition process often takes more than a century and the result is huge growth in population size (Butler 51).
The Expected Trends in Population
According to demographic scholars, the human population is expected to rise by approximately 2.7 billion to 9.2 billion by the year 2050 (“World Age Structure – Demographics”). This is in comparison to the statistics taken in 2005 that indicates that the human population by then was at around 6.5 billion. It is expected that the continents and nations in the southern part of the world will contribute in a massive way to this large population growth. Africa, South America, and some parts of Asia apart from New Zealand, Japan and Australia are the specified continents. The expected population growth in these continents between years 2005 and 2050 is 7.9 billion from 5.3 billion (“World Age Structure – Demographics”). On the contrary, the population in the northern hemisphere of the globe that is Northern America, Europe, New Zealand, and Asia are expected to maintain their human population with a slight growth of 1.25 billion from 1.22 billion. This should between 2005 and 2050.
Table 1 Estimate in Population (1950-2005) and Population Projections (2005-2050)
Source: United Nations (2007)
From the table 1 above, the demographic transition in the whole world began in the nineteenth century though at a steady rate because of the instability in the fertility rate. However, observing the table keenly you realize the northern part of the globe is yet to experience a divergent in the population growth. The growth rates are different in various continents in the north in the predicted projection between the years 2005 and 2050. For example, there is an increase in the population in Northern America of 0.45 billion from 0.33 billion while in Europe within the same projection there is a drop in population from 0.73 billion to 0.66.
Countries in the southern part of the globe have been experiencing a high growth rate in human population ever since. Asia, for example, is characterized as one of the most popularized continents in the universe. It is recorded to be having half the population of the world in 2005 with a population of 3.94 billion. Experts in demography predict that Asia will have a projection of about 34 percent by 2050 which reflects 5.27 billion. Africa on the other hand, is expected to experience more than 50 percent population increase that is an increase from 0.92 billion to 2.0 billion. Southern America’s projection in population increase in 2050 is predicted to be the same as Asia’s. There is a question of why the population rate of sub-Saharan Africa is still predicted to increase in the coming years even with the prevalence of AIDS epidemic in that area. The answer is that population is still increasing since the epidemic and its effects on the birthrates are reducing. This means that the deaths caused by AIDS are lower compared to the birthrate (UNAIDS 2007; Bongaarts et al. 2008).
The table 2 below indicates the top 10 countries with the highest populated countries based on a research conducted by the United Nations. According to the table, six of the countries with high population size are from Asia. This changes though by the year 2050. India overtakes China in population size and leads in the list. Congo and Japan join the top ten list and replaces Russia and Japan respectively. The table is a clear indicator of how the growth rate in the next years is bound to experience a lot of changes.
Table 2 Largest countries by population size in 1995 and 2050 Projection
Source: United Nations (2007)
Fertility and Mortality
A good explanation as to why the population size of the world increases each year is that the fertility is quite higher than the mortality rate. For instance, the rate of population size increase per year between the years 2000 and 2005 is said to be at 1.17 percent. This figure is similar to the difference between the fertility rate and mortality rate in the same years which is 2.03 percent and 0.86 percent respectively (Todaro 792). Another factor that can be said to be influencing the population growth in a country is migration among neighboring countries. However, this does not apply to population data collected by region or continent since the effects brought about by migration are too small. Primarily, the birthrate and death rate are the determinants on the population growth.
Fertility
According to statistics by the United Nations as illustrated in table 2 above, the total fertility rate (TFR) in the south part of the world is high from the 1950s. With those figures, it approximated that every woman would give birth to a total of six children. During these years there was no use of family planning or birth control methods to regulate the birthrate. However, there are changes in the years after. There is a decrease in the fertility rate in both Asia and South America from 1960. Africa, on the other hand, had a very minimal change in the fertility. This technically indicates how divergent the demographic transition was in the south part of the globe (Lutz, Sanderson, and Scherbov). The same divergent trends are reflected in the statistics between 2000 and 2005. The fertility rate in Africa is approximated to be five births per woman while the rates in Asia and Southern America are on average three births per woman.
However, the general fertility rate in the entire south part of the world is seen to reduce from six children per woman to three in the half of the nineteenth century. This fact can be attributed to the idea that nations in the south area have adopted birth control measures. In other countries like China, there are formulated policies that hinder women to have more than one child (Lutz, Sanderson, and Scherbov). In Africa, the projections indicate that the fertility rate per woman may take some time to decline especially with the state of economic development in Africa. The high fertility rate in the south therefore is the reason for high population growth in the coming years since the fertility rate in the north is constant. It still expected to be constant in the projections.
Mortality
Life expectancy and mortality have also been components in the demographic transitions. The levels and rates of mortality have changed significantly over the years (Tienda 587-616). The continents in the south are the focus in the improvement in the life expectancy rates. Africa for example, experienced a great improvement from an average forty years between the years 1950 to 1955 to 64 years in the years 2000 to 2005. Asia and Southern America experienced an improvement in life expectancy and caught up with the continents from North by the year 2000. Africa however, experienced a drop in life expectancy and an increase in mortality rate from 1990. This was right after Africa was affected by the epidemic AIDS (Yaukey, Aderton, and Lindquist). The life expectancy in Asia and Southern America were at 68 years and 72 years respectively. The north continents on the hand have a lower mortality rate as expected with Europe at 74 years in life expectancy while that of Northern America is at 78 years. According to the projections, the mortality rate of the north part of the globe is expected to reduce to a life expectancy of 82 years (Frauenthal 64-73). The life expectancy in the Asian countries and that of Latin Americans is expected to rise closer to that of the northern continents. Due to AIDS Africa is still expected to be the last in the list of life expectancy.
Trends in Population Age Composition
The decrease in the birthrates and mortality rate has a great impact on the age composition in any population. Demographic transition plays a huge role in the age composition. Typically, countries that are in the early phase of demographic transition have a majority of their population composition being young people. Countries in the final phases, on the other hand, are majorly composed of less young people compared to those that are just beginning the transition. Most countries in the south part have a very young age composition. South America, West Asia, Southern America, and South Africa have approximately half of their population with 25 years. Of this statistics, 62 percent are from Africa. This is quite the opposite in the north part of the world why the population of those under age 25 is small. In Europe and Northern America combined only 33 percent of the total population size is below 25 years (United Nations 1962, 1973, 2007).
Age Population Ratio
The modifications and changes in the age composition of the world have serious effects on the economy. Education, social security, and healthcare are some of the sectors that are affected in the entire world population with these changes. The age-summary ratio (DR) is often used to asses and to show the developments in the age population ratio. The DR’s goal is to measure how many people below the age 15 and those above 65 years are “dependents”. This means that the rest of the population between 15 and 65 years are active and productive (United Nations 1962, 1973, 2007). However, this is not always the case there are people within the age composition that may not be productive due to disabilities, sicknesses and many other factors. Statistics by the United Nations indicate that there are changes that occurred in the DR between the years 1950-2000 and 2000-2005. The ratio first increases in the first years before declining in the last phase that is between 2000 and 2005.
Population Momentum
The demographic transition only comes to an end when the growth rate of the population levels down to zero. For this to successfully take place, there are three conditions that must be met. One, the fertility rate levels down to approximately two children per woman, if it goes beyond that then population growth continues. The second condition is that the number of death starts increasing. Scientifically this is not likely to happen since there are a number of significant discoveries in technology and healthcare. And the last condition is that the age composition adjusts itself to whatever happens after demographic transition. This adjustment might take years and years to be achieved.
Population momentum can be defined as the increase in population size that still occurs even after the fertility rate per woman has reduced to two children per woman (Tienda 587-616). Population momentum often occurs due to the younger age composition in the population. When there are more young people in the population the number of birth rates is still expected to increase since there are many more young people still expected to grow and give birth (Bongaarts & Bulatao, 1999).
This research is clear indication of how there have been changes and there still will be in the development of the human population. The population size of the entire universe is growing at an immense rate. From 1950 to date, the population size has grown by more than four million. This is one instance of the demographic transitions happening in the world. Other instances are the differences in the mortality and fertility rates the world is experiencing. The fertility rate in the south part of the globe is still high, higher than the rate of mortality. Hence the population size is still expected to grow especially in Africa and other parts of Asia and South America. With all these transitions there has risen a divergence in the age composition in different parts of the world. The northern continents are mainly composed of an older age while those continents in the south experience a much younger age composition. These are effects of the demographic transition. The population size is still growing and is expected to hit 9.2 billion by the year 2050. This increase comes with serious effects on the environment and the economy. It should act as a signal to the universe to prepare and put down measures that may help the world counter such effects.
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