Human Population Growth PDF

chapter III HUMAN POPULATION  3.1. PERSPECTIVES ON POPULATION GROWTH As you will see later in this chapter, there is some evidence that population growth already is slowing, but whether we will reach equilibrium soon enough and at a size that can be sustained over the long term remains a...

chapter III HUMAN POPULATION  3.1. PERSPECTIVES ON POPULATION GROWTH As you will see later in this chapter, there is some evidence that population growth already is slowing, but whether we will reach equilibrium soon enough and at a size that can be sustained over the long term remains a difficult but vital question. 3.1. Does environment or culture control human population growth? Since the time of the Industrial Revolution, when the world population began growing rapidly, individuals have argued about the causes and consequences of population growth. In 1798, Thomas Malthus (1766–1834) wrote An Essay on the Principle of Population, changing the way European leaders thought about population growth. Eventually, he argued, human populations would outstrip their food supply and collapse into starvation, crime, and misery. He converted most economists of the day from believing that high fertility increased industrial output and national wealth to believing that per capita output fell with rapidly rising population. 3.1. Does environment or culture control human population growth? In Malthusian terms, growing human populations are limited only by disease or famine, or social constraints that compel people to reduce birth rates—late marriage, insufficient resources, celibacy, and “moral restraint.” However, the economist Karl Marx (1818–1883) presented an opposing view that population growth results from poverty, resource depletion, pollution, and other social ills. Slowing population growth, claimed Marx, requires that people be treated justly, and that exploitation and oppression be eliminated from social arrangements. Both Marx and Malthus developed their theories about human population growth when the world, technology, and society were understood much differently than they are today. Some believe that we are approaching, or may have surpassed, the earth’s carrying capacity. 3.1. Does environment or culture control human population growth? Joel Cohen, a mathematical biologist at Rockefeller University, reviewed published estimates of the maximum human population size the planet can sustain. The estimates, spanning 300 years of thinking, converged on a median value of 10–12 billion. We are more than 7 billion strong today, and still growing, an alarming prospect for some. Cornell University entomologist David Pimentel, for example, has said, “By 2100, if current trends continue, twelve billion miserable humans will suffer a difficult life on Earth.” In this view, birth control should be our top priority. 3.1. Technology increases carrying capacity for humans Optimists argue that Malthus was wrong in his predictions of famine and disaster 200 years ago because he failed to account for scientific and technical progress. ✔food supplies have increased faster than population growth since Malthus’s time ✔progress in agricultural productivity, engineering, information technology, commerce, medicine, sanitation, and other achievements of modern life have made it possible to support approximately 1,000 times as many people per unit area as was possible 10,000 years ago …knowing your ecological footprint is essential ECOLOGICAL footprint  ECOLOGICAL footprint the impact of human activities measured in terms of the area of biologically productive land and water required to produce the goods consumed and to assimilate the wastes generated.  footprint =DEMAND the land and water area NEEDED TO PRODUCE THE RESOURCES we use and to absorb our wastes ECOLOGICAL footprint  biocapacity = SUPPLY the amount of biologically productive AREA THAT IS AVAILABLE TO PROVIDE THE resources we use to absorb our and waste ECOLOGICAL footprint biocapacity footprint  ECOLOGICAL DEBTOR biocapacity footprint ECOLOGICAL DEFICIT  ECOLOGICAL CREDITOR biocapacity footprint ECOLOGICAL RESERVE 3.2.3. Population growth could bring benefits Julian Simon Ester Boserup People are the An increase in “ULTIMATE RESOURCE” population would no evidence shows that stimulate technologies to pollution, crime, increase food production unemployment, crowding, Necessity is the mother the loss of species, or any of invention. other resource limitations will worsen with population growth.  3.1. PAST AND CURRENT POPULATION GROWTH ARE VERY DIFFERENT WHY and HOW? Birth rate is relatively higher that mortality rate wherein nearly 5 children is being added every second and on same period 1 person or 2 dies. By that, the variation between births and deaths signifies a net gain of approximately 2.5 additional humans per second (on average) in the world’s population. We add around 75 million more people to the globe at a rate of 1.1 percent per year. THE WORLD’S LARGEST COUNTRIES 2010 2050 Some countries in the developing Population Population world are growing so fast that Country Country (Millions) (Millions) they will reach immense China 1,339 India 1,628 India 1,204 China 1,437 population sizes by the middle of U.S. 313 U.S. 420 the twenty-first century. Indonesia 240 Nigeria 299 China was the most populous country Brazil 203 Pakistan 295 throughout the twentieth century; Pakistan 178 Indonesia 285 India is expected to pass China in the Bangladesh 159 Bangladesh 231 twenty-first century. Nigeria, which Nigeria 155 Brazil 220 had only 33 million residents in 1950, Russia 142 Congo 183 is forecast to have 299 million in 2050. SOURCE: Data from the U.S. Census Bureau, 2012 SOURCE: Data from the U.S. Census Bureau, 2012.  FACTORS in 3.2determining HUMAN POPULATION GROWTH 3.2. Fertility varies among cultures and at different times Fecundity is the physical ability to reproduce, whereas fertility is the actual production of offspring. Those without children may be fecund but not fertile. The most accessible demographic statistic of fertility is usually the crude birth rate, the number of births in a year per thousand persons. It is statistically “crude” in the sense that it is not adjusted for population characteristics, such as the number of women of reproductive age. ✔The total fertility rate is the number of children born to an average woman in a population during her entire reproductive life. ✔Zero population growth (ZPG) occurs when births plus immigration in a population just equal deaths plus emigration. 3.2. Fertility varies among cultures and at different times ✔In most tribal or traditional societies, food shortages, health problems, and cultural practices limit total fertility to about 6 or 7 children per woman, even without modern methods of birth control. ✔As in Brazil, fertility rates have declined dramatically in every region of the world except Africa over the past 50 years. ✔The average family in Mexico in 1975, for instance, had 7 children. By 2010, however, the average Mexican woman had only 2.3 children. Similarly, in Iran, total fertility fell from 6.5 in 1975 to 2.04 in 2010. ✔China’s one-child-per-family policy decreased the fertility rate from 6 in 1970 to 1.7 in 2010. 3.3.3. Mortality offsets births In demographics, crude death rates (or crude mortality rates) are expressed in terms of the number of deaths per thousand persons in any given year. ✔Countries in Africa where health care and sanitation are limited may have mortality rates of 20 or more per 1,000 people. ✔Wealthier countries generally have mortality rates around 10 per 1,000. ✔Rapidly growing, developing countries, such as Brazil, often have lower crude death rates (6 per 1,000 currently) than do the more- developed, slowly growing countries, such as Denmark (12 per 1,000), even though their life expectancies are considerably lower. The number of deaths in a population is sensitive to the population’s age structure 3.3.4. Life expectancy is rising worldwide Life expectancy is the average age that a newborn infant can be expected to attain in any given society. Life span is the oldest age to which a species is known to survive. ✔The oldest age that can be certified by written records was that of Jeanne Louise Calment of Arles, France, who was 122 years old at her death in 1997. ✔For most of human history, life expectancy in most societies probably was 35 to 40 years. ✔The average life expectancy rose from about 40 to 67.2 years over the past 100 years. Life expectancy is another way of expressing the average age at death LIFE EXPECTANCY AT BIRTH FOR SELECTED COUNTRIES IN 1900 AND 2012 ✔The twentieth century saw a global transformation in human health unmatched in history. 1900 2012 ✔The greatest progress was in COUNTRY Femal Male Female Male developing countries. e India 23 23 64 67 ✔Longer lives were due Russia 31 33 62 76 primarily to better nutrition, improved sanitation, clean United 46 48 77 82 States water, and education, rather Sweden 57 60 83 85 than to miracle drugs or high- Japan 42 44 85 87 tech medicine. SOURCE: World Health Organization, 2014.  3.4 FERTILITY IS INFLUENCED BY CULTURE A number of social and economic pressures affect decisions about family size, which in turn affects the population at large. In this section, we will examine both the positive and negative pressures on reproduction. 3.4.1. People want children for many reasons Factors that increase people’s desires to have babies are called pronatalist pressures. Raising family may be the most enjoyable and rewarding part of many people’s lives. Children can be a source of pleasure, pride, and comfort. They may be the only source of support for elderly parents in countries without a social security system. ✔ Children are valuable to the family not only for future income but even more as a source of current income and help with household chores ✔ Society has a need to replace members who die or become incapacitated. ✔ Some societies look upon families with few or no children with pity or contempt, and for them the idea of deliberately controlling fertility may be shocking, even taboo. ✔ Male pride often is linked to having as many children as possible. SOURCE: Data from the U.S. Census Bureau, 2012. 3.4.2. Education and income affect the desire for children Higher education and personal freedom for women often result in decisions to limit childbearing. A desire to spend time and money on other goods and activities offsets the desire to have children. ✔ Education and socioeconomic status are usually inversely related to fertility in richer countries. ✔ In some developing countries, however, fertility initially increases as educational levels and socioeconomic status rise. ✔ The Great Depression in the 1930s made it economically difficult for families to have children, and birth rates were low. ✔ The birth rate increased at the beginning of World War II (as it often does in wartime) A “baby boom” followed World War II, as couples were reunited, and new families started 3.5. A DEMOGRAPHIC TRANSITION CAN LEAD TO STABLE POPULATION SIZE In 1945, demographer Frank Notestein pointed out that a typical pattern of falling death rates and birth rates due to improved living conditions usually accompanies economic development. He called this pattern the demographic transition from high birth and death rates to lower birth and death rates. It shows an idealized model of a demographic transition. This model is often used to explain connections between population growth and economic development. THE DEMOGRAPHIC TRANSITION MODEL Theoretical birth, death, and population growth rates in a demographic transition accompanying economic and social development. In a predevelopment society, birth and death rates are both high, and total population remains relatively stable. During development, death rates tend to fall first, followed in a generation or two by falling birth rates. Total population grows rapidly until both birth and death rates stabilize in a fully developed society. 3.5.2. Many countries are in a demographic transition Some countries have had remarkable success in population control. In Thailand, China, and Colombia, for instance, total fertility dropped by more than half in 20 years. Morocco, Jamaica, Peru, and Mexico all have seen fertility rates fall by 30 to 40 percent in a single generation. Surprisingly, one of the most successful family planning advances in recent years has been in Iran, a predominantly Muslim country. SOURCE: Data from the U.S. Census Bureau, 2012. The following factors help stabilize populations: ✔ Growing prosperity, urbanization, and social reforms that accompany development reduce the need and desire for large families in most countries. ✔ Technology is available to bring advances to the developing world much more rapidly than was the case a century ago, and the rate of technology exchange is much faster than it was when Europe and North America were developing. ✔ Less-developed countries have historic patterns to follow. They can benefit from the mistakes of more-developed countries and chart a course to stability relatively quickly. ✔ Modern communications (especially television and the Internet) provide information about the benefits of and methods for social change. SOURCE: Data from the U.S. Census Bureau, 2012. 3.6. FAMILY PLANNING GIVES US CHOICE Family planning allows couples to determine the number and spacing of their children. It doesn’t necessarily mean fewer children—people could use family planning to have the maximum number of children possible—but it does imply that the parents will control their reproductive lives and make rational, conscious decisions about how many children they will have and when those children will be born, rather than leaving it to chance. 3.6.2. Today there are many options Modern medicine gives us many more options for controlling fertility than were available to our ancestors. More than 100 new contraceptive methods are now being studied, and some appear to have great promise. ✔ Vaccines for women are being developed that will prepare the immune system to reject the hormone chorionic gonadotropin, which maintains the uterine lining and allows egg implantation, or that will cause an immune reaction against sperm. ✔ Injections for men are focused on reducing sperm production and have proven effective in mice. Without a doubt, the contemporary couple has access to many more birth-control options than their grandparents had. SOURCE: Data from the U.S. Census Bureau, 2012. 3.7. WHAT KIND OF FUTURE ARE WE CREATING NOW? Because there’s often a lag between the time when a society reaches replacement birth rate and the end of population growth, we are deciding now what the world will look like in a hundred years. How many people will be in the world a century from now? Most demographers believe that world population will stabilize sometime during the twenty-first century. Population projections for different growth scenarios The optimistic (low) projection suggests that world population might stabilize just below 8 billion by 2050 and then drop back below current levels by the end of the century. This doesn’t seem likely. The medium projection shows a population of about 9.4 billion in 35 years, while the high projection would reach nearly 12 billion by midcentury. Recent progress in family planning and economic development have led to significantly reduced estimates compared to a few years ago. The medium projection is 9.4 billion in 2050, compared to previous estimates of over 10 billion for that date. SOURCE: UN Population Division, 2015. Successful family planning programs often require significant societal changes ✔ improved social, educational, and economic status for women (birth control and women’s rights are often linked) ✔ improved status for children (fewer children are born if they are not needed as a cheap labor source) ✔ acceptance of calculated choice as a valid element in life in general and in fertility in particular (the belief that we have no control over our lives discourages a sense of responsibility) ✔ social security and political stability that give people the means and the confidence to plan for the future ✔ the knowledge, availability, and use of effective and acceptable means of birth control SOURCE: Data from the U.S. Census Bureau, 2012. Fertility rates by country nearly half the world population lives in countries where the total fertility rate is at or close to the replacement rate SOURCE: UN Population Division, 2015. where wars, corruption, colonial history, religious tensions, and other factors have prevented economic and social development while perpetuating high population growth, can we overcome all these problems and create a more HUMANE, SUSTAINABLE WORLD?