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Population, Part Two

Population Home Part I Part II
Part III Part IV Part V

Factors that Contribute to the Current and Future Population

Natural Increase

The number of people born minus the number of people who die in a given year represents the natural increase of population. In order to achieve a stable population, for every person that is born, one person must die. The world's population today is far from stable, with many more people coming into the world than leaving. Even though some countries are averaging a replacement rate of 2 children per couple, their population may not be stabilizing because there are many more young couples having kids than there are aged couples passing away. This is compounded by the advancements of medicine and public health, which have lowered the incidence of infant mortality and famine-related death, and lengthened life expectancy in many regions.

The world averages about 23 births and 9 deaths per thousand people per year, a natural increase of 14 people per thousand per year (9). Another way of saying it is the world population adds 1.4 people per hundred per year, or an increase of 1.4%. This is the global average, however, as birth rates and death rates vary widely from country to country. While Middle Africa has a birth rate of almost 45 per thousand, Eastern and Southern Europe have birth rates of 10 per thousand.

The values used to calculate natural increase are also used to figure out what stage a country has reached in the demographic transition.* The demographic transition is a 3-stage identification tool that indicates socioeconomic progress in comparison to the birth and death rates of a country. High birth rates and high death rates characterize the first stage. High birth rates but declining death rates mark the second stage. Declining birth rates and stabilizing death rates characterize the third stage, marking a complete transition to population stabilization. Many industrialized countries, such as Australia , Japan , the United States , and some European countries are at stage three. Meanwhile, most of the increase in world population can be attributed to the developing countries that have only reached stage two.

*When calculating a specific country's natural increase, additions or subtractions due to immigration are not included.


Immigration to cities or across international borders is spurred by many factors. Environmental degradation due to population growth is one motivation to migrate. With too many people living in one area, food and water shortages may become a frequent concern, or "human-induced climate change" may alter the region to the point that it is no longer a desirable place to live (12). Political unrest is another reason that people migrate.

Unemployment is one of the main reasons for immigration. In regions that lack economic opportunity people often seek employment in other countries where they perceive good jobs are plentiful. Today there are over 1 billion unemployed or underemployed people in the world. Considering that "the global economy must generate at least 40 million additional jobs each year to keep pace with population growth," the future job market may cause unprecedented levels of immigration toward the more developed economies.

Growth Rate

Natural increase combined with immigration equals the total population growth rate of a region. The current global growth rate is about 1.33%, which is about 215,000 new mouths to feed every 24 hours. Considering that in the 1960s it was about 2.04%, our rate of growth has actually been falling in the last few decades. Most of the future population growth is projected to happen outside of the industrialized nations. In fact, "by 2025, 84 percent of the world's population will live in developing countries."(13) By 2050 the population of the more developed countries will be two percent less than in 1998, while the less developed regions will show a 64 percent increase, the fastest growth happening in Africa . " Africa 's share in the world population growth will increase from the current 22 percent to 55 percent in 2045-2050." Today, "Africa has the highest average population growth rate among various world regions," at 2.8%, while Europe has the lowest, at 0.2% (14).

Global Growth Rates (3)








0.87%    0.34%   -0.23%

*rates for high, medium, and low projections

All in all, 10 countries account for 60% of the world's population growth; China contributes 15% and India a whopping 21%. Currently 2 out of 5 people in the world live in either China or India .

Top Ten Countries Responsible for Global Population Growth, 1995-2000(3)











United States










In general , when socioeconomic status improves, the growth rate declines, but deaths due to hunger, casualties from regional conflicts, as well as disease and lethal viruses like AIDS can also make a big impact.

Fertility Rate

The fertility rate of women is one of the great unknowns when it comes to accurately predicting future population. So many factors affect a woman's decision to reproduce, and those factors are likely to change at any time, especially in developing countries whose social systems can shift rapidly.

Cultural Factors that Influence Fertility (14)

  • Lineage continuation and expansion

  • More children = more "wealth" or assets/Old age economic security for parents

  • Help in agricultural work

  • Male-dominant decision making

  • Symbol of high male virility

  • Polygyny (the practice of having more than one wife)

  • Child Fosterage

Direct Factors that Influence Fertility (14)

  • Early marriage

  • Postpartum and peri-partum practices

  • Natural and pathological sterility

  • High infant mortality rates

  • High maternal mortality rates

"If fertility remained at current levels , the population would reach 296 billion in just 150 years. Even if it dropped to 2.5 children per woman and then stopped falling, the population would still reach 28 billion." But future population projections are based on a worldwide reduction in fertility because as the fertility rates in many countries drop closer to the replacement level of 2 children per woman, the world is inching toward population stability. "During the last 25 years, the number of children per couple has fallen from 6.6 to 5.1 in Africa, from 5.1 to 2.6 in Asia, and from 5.0 to 2.7 in Latin America and the Caribbean ." The total fertility rate in the developing countries today is 3.1 children per woman, while in developed countries it is 1.6. In order to meet the middle population projection for 2050, the total world fertility rate must drop from the current 2.7 children per woman to 2.1 (11). Sixty-one countries, which comprise 44% of the world's population, are already at or below replacement level, and 20 of them have been below it for more than 20 years.

There are many factors that can lower the fertility rates of women, both in developing and industrial countries. A basic education in general seems to be an important deterrent to marrying early and reproducing, especially if women complete secondary school. "In every society for which data are available, the more education women have, the fewer children they have." For instance, in Peru, a woman with 10 years of schooling usually has 2-3 children, while a woman who has had no education has 7-8.

Knowledge of reproduction and contraceptive methods helps educated women make more informed decisions about their sexual activity and its resulting affect on their life. For example, "teenagers in many European countries are as sexually active as American teens, but their premarital pregnancy and abortion rates are much lower because they are more informed about contraception and use it more frequently."(6) Such a lack of information or accessibility to contraception may explain why the U.S. has one of the highest rates of teen pregnancy of the industrialized countries; 60% of pregnancies and 40% of births in the United States are unintended (16).

Being self-supportive also helps women profit outside of the home or agricultural sector. "A woman with an independent income does not have to marry young or barter sex or childbearing for support." In addition, her experience of economic freedom may reduce her drive for reproducing, whether because of the stimulation of independence and self-worth, the lack of need for more hands around the house, or the loss of adhesion to traditional cultural ways. Even if being self-supportive is out of the question for some women, studies have shown that women who are able to make household decisions "devote more income to maintaining better nutrition for their families, and are also more prone to set aside money for education and health care." Empowering and educating women will make for fewer, healthier children, thereby slowing population growth.

Factors Related to Lower Fertility Rates

  • Basic rights: decision-making in the home, voting, owning land, having a job

  • Knowledge of reproduction and contraceptive methods

  • Access to contraception

  • Education/Literacy

  • Income independent of a man

Overall, high fertility rates and closely spaced births hinder the health and progress of people in many ways. Frequent childbirth generates more stress on women's bodies and children receive less health care and education. The environment and other common property are more rapidly degraded, and there is less water and land for crops to go around with more people on the planet. With less nourishment, fewer health services, and little education, people are more likely to be locked into poverty due to high fertility.

Infant Mortality

As mentioned earlier developing countries have had the most impact on the world's population growth. Because many of these countries are at the second stage of the demographic transition, death rates are declining while birth rates continue to rise. This decrease in death rates is mainly due to medicinal, nutritional, and hygienic improvements that have enabled infants to survive the rigors of early childhood.

In 1950 the infant mortality rate exceeded 15%. More than 15 children died for every 100 born, or another way to state it is that one died for every 6 or 7 born. By 1998 that rate had decreased to a little under 6%, which is a marked improvement meaning that for every 17or 18 children born, only one did not survive.  

Infant mortality is also linked to a country's level of development since that usually affects their degree of health services. For comparison, for every 1,000 children born in Sierra Leone , 170 die, whereas for every 1,000 Japanese children born, 4 don't make it. In other words 1 of 6 children born in Sierra Leone dies while only 1 of 250 born in Japan does not survive.

The United States ' infant mortality rate is 7 per 1,000. That's 1 death for every 142 births. What's interesting is that Japan and the United States are assumed to be on the same level of economic and social development, yet the U.S. infant mortality rate is double that in Japan . Obviously, a country's level of development cannot be gauged solely by considering its infant mortality rate.

Life Expectancy

There is a close correlation between a society's achievement of higher levels of economic development and the ability for its people to live longer, healthier lives. Better health and a longer life expectancy also means lower birth rates. As infant mortality rates decline due to better living conditions, people have fewer children because of the increased likelihood that nearly all will survive.

One indicator of an aging population is the median age of people. If you were to line up all 5.9 billion people in the world from youngest to oldest, the age of the person standing in the middle would represent the median age. The median age has gotten older through time since the population as a whole has aged. In 1950 the median age was 23.5 and by 1998 had only risen to 26.1. But in 2050 the population will have aged dramatically to a median of 37.8 years.

HIV & AIDS and Other Diseases

In some regions the HIV virus has reversed the gains that life expectancy had made in the last few decades. Africa has been hit the hardest. Currently, there are 30 million HIV-positive people in the world. Africa is home to 26 million of those victims. One of every 5 adults in many African countries is expected to die in the next decade due to AIDS. The disease is taking its toll on "the young professionals in the prime of life the very agronomists, engineers, and teachers needed to develop the economy." Botswana in particular has "the highest prevalence of HIV in the world," where 1 of every 4 adults, or 25% of the population, is infected.

Life expectancy in Botswana has fallen from 61 years in 1990 to 44 years in 1998 and is expected to fall to 41 years in 2000-2005. Considering that life expectancy would have been greater than 67 years, that's more than 26 years of life per person lost to the disease. The growth rate will have decreased from 2.9% in 1990 to 1.2% in 2000-2005. By 2025, Botswana 's population "may be 23 percent smaller than it would have been in the absence of AIDS." But fertility remains high, so the population will probably still double from 1995-2050. Other African countries are also suffering heavily. As death rates climb in Zimbabwe due to AIDS, the country's population is expected to stabilize by 2002, marking regression back to the first stage of the demographic transition.