Study Guide

Chapter 6

HISTORY AND GLOBAL

DISTRIBUTION 1

6.1 HISTORY AND GLOBAL DISTRIBUTION

6.1.1 INTRODUCTION

A population is a group of individuals living together in a given area at a given time. Changes in populations are termed population dynamics. The current human population is made up of all of the people who currently share the earth. The �rst humans walked the planet millions of years ago. Since that time, the number of humans living on the planet and where they live has constantly changed over time. Every birth and death is a part of human population dynamics. Each time a person moves from one location to another, the spatial arrangement of the population is changed, and this, too, is an element of population dynamics. While humans are unique in many ways as a species, they are subject to many of the same limiting forces and unexpected events of all populations of organisms.

In 1999, the human population crossed the six billion mark. At current growth rates, the population will double within 50 years. Long ago, when the human population was small, the doubling of the population had little impact on the human population or its environment. However, with the size of today’s population, the e�ect of doubling the population is quite signi�cant. Already, most of the people of the world do not have adequate clean water, food, housing and medical care, and these de�ciencies are at least partially the result of over population. As the population continues to grow, competition for resources will increase. Natural disasters and political con�icts will exacerbate the problems, especially in the more stressed regions of developing nations. The survivors of this competition will likely be determined by factors such as place of birth and educational opportunities.

6.1.2 POPULATION GROWTH

Human populations are not stagnant. They naturally change in size, density and predominance of age groups in response to environmental factors such as resources availability and disease, as well as social and cultural factors. The increases and decreases in human population size make up what is known as human population dynamics. If resources are not limited, then populations experience exponential growth. A plot of exponential growth over time resembles a “J” curve. Absolute numbers are relatively small at �rst along the base of the J curve, but the population rapidly skyrockets when the critical time near the stem of the J curve is reached.

For most of the history of modern humans (Homo sapiens), people were hunter-gatherers. Food, especially meat from large mammals, was usually plentiful. However, populations were small because the nomadic life

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did not favor large family sizes. During those times, the human population was probably not more than a few million worldwide. It was still in the base of the J growth curve.

With the end of the last Ice Age, roughly 10,000 years ago, the climates worldwide changed and many large mammals that had been the mainstay of human diet became extinct. This forced a change in diet and lifestyle, from one of the nomadic hunter-gatherer to that of a more stationary agricultural society.

Humans began cultivating food and started eating more plants and less meat. Having larger families was possible with the more stationary lifestyle. In fact, having a large family increasingly became an asset, as extra hands were needed for maintaining crops and homes. As agriculture became the mainstay of human life, the population increased.

As the population increased, people began living in villages, then in towns and �nally in cities. This led to problems associated with overcrowded conditions, such as the buildup of wastes, poverty and disease. Large families were no longer advantageous. Infanticide was common during medieval times in Europe, and communicable diseases also limited the human population numbers. Easily spread in crowded, rat-infested urban areas, Black Death, the �rst major outbreak of the Bubonic Plague (1347-1351) drastically reduced the populations in Europe and Asia, possibly by as much as 50 percent.

Starting in the 17th Century, advances in science, medicine, agriculture and industry allowed rapid growth of human population and infanticide again became a common practice.

The next big in�uence on the human population occurred with the start of the Industrial Revolution in the late 18th century. With the advent of factories, children became valuable labor resources, thereby contributing to survival, and family sizes increased. The resulting population boom was further aided by improvements in agricultural technology that led to increased food production. Medical advancements increased control over disease and lengthened the average lifespan. By the early 19th century, the human population worldwide reached one billion. It was now in the stem of the J curve graph. As the world approached the 20th century, the human population was growing at an exponential rate.

During the 20th century, another important event in human population dynamics occurred. The birth rates in the highly developed countries decreased dramatically. Factors contributing to this decrease included: a rise in the standard of living, the availability of practical birth control methods and the establishment of child education and labor laws. These factors made large families economically impractical. In Japan, the birth rate has been so low in recent years that the government and corporations are worried about future labor shortages. Therefore, they are actively encouraging population growth. In contrast, the populations in less well-developed countries continue to soar. Worldwide, the human population currently exceeds six billion and continues to grow exponentially. How much more the world population will grow is a topic of intense speculation. One thing is certain: exponential growth cannot continue forever, as earth’s resources are limited.

6.1.3 POPULATION DEMOGRAPHICS

Human demography (population change) is usually described in terms of the births and deaths per 1000 people. When births of an area exceed deaths, population increases. When the births of an area are fewer than deaths, the population decreases. The annual rate at which the size of a population changes is:

Figure 6.1

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During the year 2000, the birth rate for the world was 22 and the death rate was 9. Thus, the world’s population grew at a rate of 1.3 percent. The annual rate of population change for a particular city or region is also a�ected by immigration (movement of people into a region) and emigration (movement out of a region).

Figure 6.2

Highly industrialized nations, like the United States, Canada, Japan and Germany, generally have low birth and death rates. Annual rates of natural population change vary from -0.1% to 0.5%. In some industrial nations (e.g. Germany and Russia) death rates exceed birth rates so the net population decreases over time. Newly industrialized countries (e.g. South Korea, Mexico and China) have moderate birth rates and low death rates. The low death rates result from better sanitation, better heath care and stable food production that accompany industrialization. The annual rates of natural population change are about 1 percent to 2 percent in these countries. Countries with limited industrial development (e.g. Pakistan and Ethiopia) tend to have high birth rates and moderate to low death rates. These nations are growing rapidly with annual rates of natural population change exceeding 2 percent.

Several factors in�uence human fertility. Important factors in�uencing birth and fertility rates in human populations are: a�uence, average marriage age, availability of birth control, family labor needs, cultural beliefs, religious beliefs and the cost of raising and educating children.

The rapid growth of the world’s population over the past 100 years is mainly results from a decline in death rates. Reasons for the drop in death rates include: better nutrition, fewer infant deaths, increased average life span and improvements in medical technology.

As countries become developed and industrialized, they experience a movement from high population growth to low population growth. Both death and birth rates decline.

These countries usually move from rapid population growth, to slow growth, to zero growth and �nally to a reduction in population. This shift in growth rate with development is called the “demographic transition.” Four distinct stages occur during the transition: pre-industrial, transitional, industrial and post-industrial.

During the pre-industrial stage, harsh living conditions result in a high birth rate and a high death rate. The population grows very slowly, if at all. The transitional stage begins shortly after industrialization. During this phase, the death rate drops because of increased food production and better sanitation and health conditions, but, the birth rate remains high. Therefore, the population grows rapidly.

During the industrial stage, industrialization is well established in the country. The birth rate drops and eventually approaches the death rate. Couples in cities realize that children are expensive to raise and that having large families restrict their job opportunities. The post-industrial stage occurs when the birth rate declines even further to equal the death rate, thus population growth reaches zero. The birth rate may eventually fall below the death rate, resulting in negative population growth.

The United States and most European countries have experienced this gradual transition over the past 150 years. The transition moves much faster for today’s developing countries. This is because improvements in preventive health and medical care in recent decades have dramatically reduced mortality � especially infant mortality � and increased life expectancy. In a growing number of countries, couples are having fewer children than the two they need to “replace” themselves. However, even if the level of “replacement fertility” were reached today, populations would continue to grow for several decades because of the large

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numbers of people now entering their reproductive years. As a result of reduced fertility and mortality, there will be a gradual demographic shift in all countries

over the next few decades towards an older population. In developed countries, the proportion of people over age 65 has increased from 8 to 14 percent since 1950, and is expected to reach 25 percent by 2050. Within the next 35 years, those over age 65 will represent 30 percent or more of the populations in Japan and Germany. In some countries, the number of residents over age 85 will more than double.

6.1.4 PATTERNS OF RESOURCE USE

Humans have always made an impact on the environment through their use of resources. Early humans were primarily hunter-gatherers who used tools to survive. They fashioned wood and stone tools for hunting and food preparation, and used �re for cooking. Early humans developed methods for changing habitat to suit their needs and herding wild animals. As time passed, humans developed more tools and techniques and came to rely on that technology in their daily lives. Although the tools of early humans were primitive by today’s standards, they signi�cantly a�ected the environment and probably hastened the extinction of some large Ice Age mammals.

After the end of the last Ice Age, some eight to 10,000 years ago, humans began domesticating wild animals and plants. The �rst known instance of farming started in a region extending from southeastern Turkey to western Iran, known as the fertile crescent.

These early farmers domesticated crops such as chickpea, bitter vetch, grapes, olives, barley, emmer wheat, lentils, and �ax. They hybridized wheat for making bread from wild grass and emmer wheat. They also domesticated animals such as sheep, goats, cattle and pigs. The fertile crescent’s unique diversity of wild crops and animals o�ered humans a mix of basic agricultural commodities that allowed a revolution in the development of human society. With a reliable food supply, humans were able to stay in one place and be assured of having a constant supply of carbohydrates, protein, milk and oil. They had animals for transportation and plant and animal materials for producing clothing and rope. Agricultural economies soon displaced hunter-gatherer economies. Within 2,000 years, farming ranged from Pakistan to southern Italy.

Most early agriculture was subsistence farming in which farmers grew only enough food to feed their families. Agriculture underwent another important revolution about 5,000 years ago with the invention of the plow. The plow allowed humans to clear and farm larger plots of land than was otherwise possible. This increased the food supply and a concomitant increase in human population growth. More e�cient farming methods also resulted in urbanization because a few farmers could produce a large surplus of food to feed those in the urban areas.

Over the last 10,000 years, land clearing for agriculture has destroyed and degraded the habitats of many species of plants and animals. Today, growing populations in less developed countries are rapidly clearing tropical forests and savannas for agricultural use. These tropical rainforests and savannas provide habitat for most of the earth’s species. It has become clear that modern agricultural practices are not sustainable. Once-fertile areas are becoming infertile because of overgrazing, erosion and nutrient depletion. Furthermore, modern agriculture requires large inputs of energy and fertilizers, usually produced from nonrenewable fossil fuels.

The next major cultural change, the Industrial Revolution, began in England in the mid-18th century. It involved a shift from small-scale production of goods by hand to large-scale production of goods by ma- chines. Industrial production of goods increased the consumption of natural resources such as minerals fuel, timber and water by cities. After World War I, more e�cient mass production techniques were developed, and industrialization became prevalent in the economies of the United States, Canada, Japan and western Europe.

Advanced industrialization leads to many changes in human society, and some of those changes negatively a�ect the supply of natural resources and result in environmental degradation. These changes include: increased production and consumption of goods by humans, dependence on non-renewable resources such as oil and coal, production of synthetic materials (which may be toxic or non-biodegradable) and consumption of large amounts of energy at home and work.

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Other changes may have positive bene�ts. These include: creation and mass production of useful and a�ordable products, signi�cant increases in the average Gross National Product per person, large increases in agricultural productivity, sharp rises in average life expectancy and a gradual decline in population growth rates.

The information age was born with the invention of miniaturized electronics such as integrated circuits and computer central processing units. This stage in human development has changed and continues to change society as we know it. Information and communication have become the most-valued resources. This shift in turn, may lessen our in�uence on the earth’s environment through reduced natural resource consumption. For instance, in recent years energy use in the United States has not increased to the extent expected from economic growth. Online shopping, telecommuting and other Internet activities may be lessening human energy consumption.

By making good use of information technologies, less developed countries may be able to reduce potential environmental problems as their economies expand in the future. With so much information easily available, developing countries may not repeat the environmental mistakes that more developed countries made as they became industrialized.

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Chapter 7

CARRYING CAPACITY 1

7.1 CARRYING CAPACITY

7.1.1 INTRODUCTION

The human carrying capacity is a concept explored by many people, most famously Thomas Robert Malthus (1766 – 1834), for hundreds of years. Carrying capacity, “K,” refers to the number of individuals of a population that can be sustained inde�nitely by a given area. At carrying capacity, the population will have an impact on the resources of the given area, but not to the point where the area can no longer sustain the population. Just as a population of wildebeest or algae has a carrying capacity, so does a human population.

Humans, while subject to the same ecological constraints as any other species (a need for nutrients, water, etc.), have some features as individuals and some as a population that make them a unique species. Unlike most other organisms, humans have the capacity to alter their number of o�spring, level of resource consumption and distribution. While most women around the world could potentially have the same number of children during their lives, the number they actually have is a�ected by many factors. Depending upon technological, cultural, economic and educational factors, people around the world have families of di�erent sizes. Additionally, unlike other organisms, humans invent and alter technology, which allows them to change their environment. This ability makes it di�cult to determine the human K.

7.1.2 EFFECTS OF TECHNOLOGY AND THE ENVIRONMENT

When scholars in the 1700’s estimated the total number of people that today earth could sustain, they were living in a very di�erent world than our world. Today airplanes can transport people and food half way around the world in a matter of hours, not weeks or months, as was the case with ships in the 1700s. Today we have sophisticated, powered farm equipment that can rapidly plow, plant, fertilize and harvest acres of crops a day. One farmer can cultivate hundreds of acres of land. This is a far cry from the draft-animal plowing, hand planting and hand harvesting performed by farmers in the 1700s. Additionally, synthetic fertilizers, pesticides and modern irrigation methods allow us to produce crops on formerly marginal lands and increase the productivity of other agricultural lands. With the increase in the amount of land that each individual can farm, the food production has increased. This increased food production, in turn, has increased the potential human K relative to estimates from the 1700s.

Whereas technological advances have increased the human K, changes in environmental conditions could potentially decrease it. For example, a global or even a large regional change in the climate could reduce K below current estimates. Coastal �ooding due to rising ocean levels associated with global warming and deserti�cation of agricultural lands resulting from poor farming practices or natural climate variation could cause food production to be less than that upon which the human carrying capacity was originally estimated.

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There are those who believe that advances in technology and other knowledge will continue to provide the means to feed virtually any human population size. Those who subscribe to this philosophy believe that this continuous innovation will “save us” from ourselves and changes in the environment.

Others believe that technology will itself reach a limit to its capabilities. This group argues that resources on earth � including physical space � are limited and that eventually we must learn to live within our means. Aside from the physical limitations of the earth’s natural resources and food production capabilities, we must consider the conditions we are willing to live with.

7.1.3 EFFECT OF STANDARD OF LIVING

Given the wherewithal to do so, humans have aesthetic expectations in their daily lives. This is a considera- tion that is less evident in other species. While the earth might be able to hold many more than the current human population of six billion (estimates of the human K with current technology go as high as 50 billion) at some point people will �nd it unacceptable to live with the crowding and pollution issues associated with a dramatic increase in population. The qualitative measure of a person’s or population’s quality of life is called its standard of living. It is associated not only with aesthetics of surroundings and levels of noise, air and water pollution, but also with levels of resource consumption.

Americans have one of the world’s highest standards of living. While there are many who live in poverty in the United States, on average we have relatively small families, large homes, many possessions, plentiful food supplies, clean water and good medical care. This is not the case in most of the developing world.

While many nations have larger average family sizes, they have smaller homes, fewer possessions and less food. Supplies of clean water may be scarce and medical care may be inadequate. All people desire to have adequate resources to provide good care for their families, and thus population in most developing countries are striving for standard of living of developed nations.

Is it possible for all six billion people on earth to live at the same level of resource use as in the United States, Japan and Western Europe? With current technology, the answer is “no.” However, this does not mean that the people of one nation are more or less entitled to a given standard of living than those of another. What it does mean for citizens of nations like the United States is that we must reduce our current use of resources. Of all of the food purchased by the average American family, 10 percent is wasted. In addition, because most Americans are not vegetarians, we tend to eat high on the food chain, which requires more resources than a vegetarian diet.

Calculation of ecological e�ciency indicate that from one trophic level on the food chain to the next, there is only a 10 percent e�ciency in the transfer of energy. Thus people who predominately eat more grains, fruits and vegetables are getting more out of the energy required to produce the food than those who eat a lot of meat. The calories that a person gets from beef are much fewer than the calories in the grain required to raise the cattle. The person is better o� skipping the middleman � or middle cow in this case � and eating the grain. This is why many more people can be sustained on a diet that consists of a larger percentage of rice, millet or wheat, rather than of �sh, beef or chicken.

In addition to resources used to provide food, Americans use disproportionate amounts of natural re- sources such as trees (for paper, furniture and building, among other things) and fossil fuels (for automobiles, homes and industry). We also produce a great amount of “quick waste.” Packaging that comes on food in the grocery store is a good example of quick waste. The hard plastic packaging used for snack foods that is immediately removed and thrown away and plastic grocery bags are both examples of quick waste. Thus, patronizing fast food restaurants increases resource consumption and solid waste production at the same time.

The good news for the environment (from both a solid waste and a resource use standpoint) is that we can easily reduce the amount of goods and resources that we use and waste without drastically a�ecting our standard of living. By properly in�ating car tires, America could save millions of barrels of oil annually. If we were to use more renewable energy resources � like solar and wind power as opposed to petroleum and nuclear energy �there would be a reduced need to extract non-renewable resources from the earth. The amount of packaging used for goods could also be reduced. Reusable canvas bags could be used for shopping and plastic and paper grocery bags could be reused.

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At home, many waste materials could be recycled, instead of being thrown away. These relatively easy steps could reduce the overall ecological impact that each person has on the earth. This impact is sometimes termed a person’s ecological footprint. The smaller each person’s ecological footprint, the greater the standard of living possible for each person.

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