Chapter 5: The Human Population

16/10/2010 12:49


1 – How the global human population changed from early times to 1800? From 1800 until the present? What is projected over the next 50 years?


From the dawn history until the beginning of 1800 population increased slowly and variably, with periods setbacks. It was roughly 1830 before world population reached 1 billion mark.


By 1930 the population had doubled to 2 billion. 30 years later (1960) it had climbed to 4 billion. From 1930 to 1975 the population doubled. In 1987 it crossed 5 billion. In 1999 6 billion. Today it is currently growing  at 75 million a year.


On the basis of current trends UNPD projection predicts the world population will be 7 billion in 2012, 8 billion in 2024 and 9 billion in 2047. In 2050 it would reach 9.1 billion in 2050, if considered decline of fertility rates. If not considered the decline of ferltility rates UNPD estimates a population of 11.7 billion in 2050.


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2 – How is the world divided in terms of economic categories? Fertility rates? Population growth rates?


Economic categories (World Bank)


High incomes, highly developed, industrialized countries (US, Canada, Japan, western Europe, etc)

Middle income, moderately developed countries (mainly countries in Latin America, northern and southern Africa, China)

Low-income developing countries (eastern, western and central Africa, India and other countries in central Asia)


High income nations are commonly referred as developed countries. Middle and low-income countries are often grouped together as developing countries.


Terns such as more developed countries (MDCs) less developed countries being phased out. Terms as first world (high income countries), second world (communist bloc) and third world (developing countries) are obsolete.


Total fertility rates (average number of children a woman has during the life time)

In developed countries total fertility rates have declined to an average of 1.6 (exception is US with rate of 2.0).

In developing countries total fertility rate average is 2.9. In some countries it is 4 or more.


Population growth rates

In developed world the population growth rate is 0.1% per year.  The remaining countries it is 1.5% per year.


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3 – What three factors are multiplied to give the total environmental impact? Are developed nations exempt from environmental impacts? Way not?


Population, affluence and technology.

Environmental impact I:   I = P x A x T

According to the formula environmental impact (I) is proportional to population (P), multiplied by the affluence and consumption patterns (A), and multiplied by the level of technology of society (T).


Developed countries are not exempt from environmental impacts.

Given the high level of technology in industrialized countries and the affluent lifestyle that accompanies it, a fairly small population can have a very large impact on the environmental.

Despite a fairly population, the developed countries have an equally daunting problem, but on having to do with consumption, affluence, damaging technologies, and burgeoning wastes.


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4  - What are the environmental and social consequences of rapid population growth in rural developing countries?


-          Reform the system of land ownership

Rising population growth in natural developing countries has put increasing pressure on the need to reform the system of ownership.


-          Intensify cultivation of existing land to increase production per unit area

Introduction of more highly productive varieties has had a dramatic beneficial effect in supporting the growing population. However, intensifying cultivation means working the land harder. Traditional subsistence farming involved rotating cultivation among plots (three, for example). The soil had time to regenerate.

With pressures to increase productivity, plots have been put in continuous production. The results have been deterioration of the soil decreased productivity and erosion.


-          Open up new land to farm

Opening up new land for agriculture means converting natural ecosystems to agricultural production, loosing the goods and services of those ecosystems


-          Engage in illicit activities for income

Anyone who does not have a way to grow sufficient food must gain enough income to buy it and sometimes desperate people break the law to find this.


-          Emigrate to other countries, either legally or illegally

The gap between high and low-income countries is reflected in the perception of many in the poorer countries who believe they can improve their well-being by migrating.

Each year many millions migrate to US and Europe in search of a better life, a shift that has been called “replacement migration”.


-          Move to cities and seek employment

Faced with poverty and hardship of the countryside, many hundreds of millions of people in developing nations continue to migrate to cities in search of employment and better life.


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5 - Describe negative and positive impacts of affluence on the environment.


Despite of the adverse effects of affluence, increasing the average wealth of a population can effect the environment positively. As affluent country, for example US provide such amenities as safe drinking water, sanitary sewage systems and sewage treatment and the collection of disposal of refuse. Thus, many forms of pollution are held in check and the environment improves with the affluence. In addition it is possible to afford for gas and electricity, not destroying parks and woodlands for firewood. In short it is possible to afford conservation and management, better agricultural practices and pollution control, improving the environment.

Still, because US consumes so many resources it also lead the world to the production of many pollutants (using large quantities of fossil fuels it is responsible for a large share of the carbon dioxide produced)


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6 – What information is given by a population profile? How is the information presented?


A population profile is given is a bar graph showing the number or proportion of people (males and females separately) at each age for a given population.

A population profile shows the age structure of the population – that is, the proportion of people in each age group at a given date. It is a snapshot of the population at a given time.


More than a view in the past a population profile provides business and governments with a means of realistic planning for future demand for various goods and services, ranging from elementary schools to retirement homes.


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7 – How do the population profiles and fertility rates of developed countries differ from those of developing countries?


Developed countries have had a low fertility rate for some time. In Italy, in 2005, total fertility rate was 1.3. It This profile shows a dramatic increase in the number of older people, a great reduction in the number of children and young people.


Developing countries are in a situation vastly different from developed countries. Fertility rates in developing countries are generally declining, but they are still wee above replacement level. The average TRF (excluding china where it is 1.6) is currently 3.4. Thus, the pyramidal form of profile remains the same because for some years the rising generation of young adults produces an even larger generation of children.

While developed countries are facing the problems of graying population, the high fertility rates in developing countries maintain an exceedingly young population.


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8 – Compare future population projections, and their possible consequences, for developed and developing countries.


Developed countries: Taking Italy as an example

For the next 20 years the Italy’s population will be graying, s term used to  indicate that the proportion of elderly people is increasing. Overall, a net population decrease is expected.

The very low fertility rate and the expected declining population seen in Italy are typical of an increasing number of higher developed nations. Europe as a whole is on a trajectory pf population decline if only natural increase is considered. Who will produce the goods and services needed by their aging populations? Will their economies remain competitive on the world markets? The surge of older people retiring may overwhelm government pension systems;  life expectancies near 80 and retirement commonly at 60 means decades of retirement income.

In US the fertility rate reversed directions in the late 1980’s and started back up. On the basis of the lower fertility rate US population had been projected to stabilize at between 290 and 300 million  in 2050. With the higher fertility rate it is now projected to 420million. For this projection, immigration is assumed to remain constant at current levels.


Developing countries:

Fertility rates in developing countries are generally declining, but they are still well above replacement level. The average TFR (excluding China where it is 1.6) is currently 3.4.  Because of decades of high fertility rates, the population profile of developing countries have a pyramidal shape.

While highly developed countries are facing the problems of a graying population, the high fertility rates in developing countries maintain an exceedingly young population. An ideal population structure, with equal numbers of persons in each age group and a life  and a life expectancy of 75 years, would have one-fifth (20%) population in each 15 year group. By comparison, 40-50% of the population is below 15 years of age in many developing countries, whereas less than 20% of population is below the age of 15 in most developed countries.

One of the things that is means is that if a country such as Iraq is simply to maintain its current standard of living, the amount of housing and all other facilities must be almost doubled is as little as 25 years. As a result population growth of a developing country can easily cancel out its efforts to get ahead economically.


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9 – Discuss the immigration issues pertaining to developed and developing countries. What is replacement migration?


The very low fertility rate and expected decline of population is typical in high developed countries. Europe is on a trajectory of a population decline if only natural increase is considered. Who will produce goods and services needed by their aging population?  Will their economies remain competitive? The surge of older people retiring may overwhelm government pension systems; life expectancies near 80 and retirement at 60 means decades or retirement income.

One solution is to allow more immigration (replacement migration). However, it has implications for culture, religion, etc.

Some 20 million foreigners now live and work in the countries of Western Europe, most of whom do not have resident status. Fear and mistrust of these “guest workers”  has led to violent attacks on them.

Many Europeans do not want more immigration. Yet, most of these countries will have to triple their current immigration levels in the near future.


Replacement migration is the way of replace population in a specific area by incentive immigration as part of the country policy.


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10 – What is meant by population momentum, and what is the cause?


Population momentum refers to the effect of current age structures of future populations.

In a young population such as Iraq’s, momentum is positive because such a small portion of the population is in the upper age groups and many children are not entering their reproductive years. Even if this rising generation have only two children per woman the number of births will far exceed the number of deaths. This imbalance will continue until the current children reach the Iraqi limits of expectancy.

Europe’s population, on the other hand, will soon begin to experience negative population momentum as a consequence low fertility of the past three decades.


The population momentum is caused by the fertility rate trough decades.


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11 – Define the crude birthrate (CBR) and crude death rate (CDR). Describe how these rates are used to calculate the percent rate of growth and doubling time of a population.


CBR and CDR are the number of births and deaths, respectively, per thousand of population per year. By giving the data per thousand of population, populations of different countries can be compared regardless of their total size. The term crude is used because no consideration is given to what proportion of population is the CBR gives the increase (or decrease) per thousand per year. Dividing this result by 10 then yields the percent increase (or decrease) of population, mathematically:


The doubling time is the number of years it will take to a population growing at a constant percentage per year to double it. It is calculated by dividing the percentage rate of growth into 70. ( the 70 has nothing to do with population growth).




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12 – What is meant by demographic transition? Relate the epidemiologic  transition and the fertility transition, two elements of the demographic transition, to its four phases.


The concept of a stable, non growing global human population based on people freely choosing to have smaller families is possible because it is already happening in developed countries. Early demographers observed that the modernization brings among other things a decline in fertility rate. Thus, as economic development occurs, human society moves from a primitive population stability, in which low infant and childhood mortality are balanced by low birthrates. This gradual shift in the birth and death rates from the primitive to the modern condition in industrialized societies is called demographic transition.


Epidemiologic transition: By the middle of 19th century epidemics and other social conditions responsible for high rate deaths began to recede and deaths in Europe and US declined. The reduction was gradual in non developed countries, lasting for many decades and finally stabilizing at a CDR of about 10 per thousand. Today, cancer, cardiovascular and  degenerative diseases account for mortally and many people survive to old age. This pattern of change in mortally factors has been called epidemiologic transition.


Fertility transition: In now-developed countries birthdates have declined from a high 40 to 50 per thousand to 9 to 12 per thousand – a fertility transition. It happened decades after the epidemiologic transition, what resulted in rapid population growth.


The demographic transition is typically presented as occurring in the four phases.

Phase I – primitive stability resulting from a high CBR being offset by an equally high CDR.

Phase II – Declining CDR (the epidemiologic transition) Because fertility and, hence, the CBR remain high, population growth accelerates.

Phase III – CBR declines due to a declining fertility rate but population growth still significant.

Phase IV – is reached, in which modern stability is achieved by continuing low CDR, but an equally low CBR.


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13 – How the current positions of the developed and developing nations differ in the demographic transition?


In developed countries, the decrease in birthdates processed soon after, and along with, the decrease in death rates, so very rapid population growth never occurred.


In developing countries, both birth and death rates remained high until the mid-1900s. Then the sudden introduction of modern medicine caused a precipitous decline in death rates. Birthrates remained high, however, resulting in very rapid population growth.


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