Professor Marshall

LESSON 14: Population and Human Ecology

Population and Human Ecology

Please note that for this chapter while you should proceed with the material in the Steele and Price textbook, this lesson takes a slight departure from the material in the book. The material presented in this lesson will be primarily about demographic transition theory and how to apply it, and population pyramids and how to understand and apply them.


Demography is the study of the population size and composition. In the United States demography has not really been an important field of study until recently. Of late, our population as well as migration trends (both immigration and emigration) have been of concern to politicians and elected officials. This means that people who select careers that touch upon understanding populations need to have a basic understanding of the tools that demographers use. In this lesson will learn some of the basic definitions of demography and will also learn how to apply a couple of of the major tools/theories that demographers use when they examine populations.

How do we study Populations?

In Western Europe the study of demography is very popular, probably because in Western Europe countries have had to be acutely aware of shifts and trends in populations, disease, fertility, birthrates, and death rates (among other demographic trends) for centuries. Demography has just become a popular area of study in the United States among sociologists in recent years — probably because of the political focus on immigration, terrorism, and other transnational shifts in population which have been influential to our country's social policy of late.

Tools of the Trade

Demographers use specific comparisons when they do their work in comparing countries to each other. Demographers predict the problems the groups might experience using statistical analysis and longitudinal studies (of course using cohorts) to make statements about today and the future of groups, countries, and our world. From a demographic point of view cohorts are important for us to understand because the size of the cohort translates to the size of opportunity for individuals in a society:

Cohort Opportunity

The size of your birth cohort can influence the outcomes for you. If you are born into a small cohort you'll have better opportunities; this is due to there being less competition for scarce social resources. Demographers study the impact that births have on the use of resources in society, and the impact that this has on cohorts and individuals.

We also have to note what a rate is. Demographically speaking, a rate is a number per 1000 of a population. This allows us to make cross-country comparisons meaningful. Some of the more important rates that demographers compare across countries are:

  • how long we live
  • birthrates, both crude and age specific
  • death rates
  • fertility rates
  • mortality rate

The above are known as demographic variables — and these are just a few. Some other interesting pieces of data that demographers also collect include information about:

  • disease
  • why we die
  • why we migrate
  • why some populations grow and others shrink

As Steele and Price point out, there are several measures demographers use to measure a population. Each of these measurements tell us something about what a population looks like, how it will grow, and what it might look like in the future. While some of the measurements below are mentioned in your textbook, others are not butter also important one to understand:

  • Crude Birth Rate (AKA Fertility Rate) – number of births in a population. This can tell us whether or not a population will shrink or grow in the future. This is a useful forecasting tool when trying to understand whether or not we for example will have enough people to fill the jobs that will be vacated by those who are retiring in a society. Crude Birth Rate is expressed as the number of births per 1,000 of the population.
  • Zero pop. Growth (AKA ZPG) – Zero population growth is the number of people in a population which neither grows nor declines. This means that each fertile woman must have enough children to replace herself and her partner. In developed countries, this number is 2.0, and in less developed nations this number can be up to 3.0.
  • Population Replacement Rate—The average number of children women have in any given society. In the United States today, the PRR is 1.9, and continues to track downward. This means that we are no longer having enough children to replace our population.
  • Population Pyramids – visual representations of a population; there are four basic types of population pyramids and each represents a different type of population composition within a particular society or country. Demographic transition theory — theory used to explain how population shift over time in countries that industrialize; a very strong theory and a popular theory used by demographers worldwide.

A Brief History of the Study of Population in the West> Malthus

Born in 1766, Thomas Malthus was a British scholar influential to our contemporary understanding of demography. In his time, he was known for his theories on population and its increase or decline based on various factors. He believed that "[t]he power of population is indefinitely greater than the power in the earth to produce subsistence for man (Malthus 5)." This idea that led to what demographers referred to as Malthusian Theory.

Malthus wrote An Essay on the Principle of Population, and in it he lays out his theory about how population and food supplies interact. It was his belief that in time, every population would suffer either from famine or disease, or the cost of subsistence would be so great the entire population could no longer be supported.

Is important to understand that Malthus lived at the beginning of the Industrial Revolution and technology had not yet had a significant impact on agriculture. Farming methods were still quite antiquated and relied heavily on human labor. It's also important to understand that because of the Industrial Revolution in a large influx of population into urban centers we started to see a rapid increase in populations overall. This alarmed Malthus and he felt that populations would outstrip the food supply in very short time. He theorized that population growth would be a major social problem for every society that continues to progress. He proposed several solutions to keep this from happening:

The first solution is a check that holds the population within its resources by raising the death rate, known as a positive check. This would occur naturally with situations such as disease which would cull the population of the elderly and thus reduce the size of the overall population. The next check has the same effect, lowering the birth rate, known as a preventative check. This was problematic for Malthus as due to his religious background he could not advocate for birth control (it was against his religious background as a reverend). He wasn't quite sure how this type of solution would happen without the use of some type of birth control or preventative measure, but couldn't quite bring himself to encourage individuals to use methods which would lower the birth rate.

He criticized the notion that agriculture could be infinitely expanded and improved to support an increasing population, though he admitted he was unsure what the limit was. He emphasized moral restraint, such as abstinence and waiting to have children until you could support a family, as another check to keep the population balanced, although again it was wholly unclear how he proposed abstinence and waiting were going to be solutions to an entire society's population issues.

In his time, Malthus led the way in research and theory regarding population, and his theories paved the way for those such as Demographic Transition Theory.

Demographic Transition Theory

Demographic Transition Theory (also sometimes referred to as Demographic Transition Model) is a sociological theory used to demonstrate and predict change in population given several factors of a population. It has four confirmed stages, with a theorized fifth stage. The first, second, third, and fourth stages can be compared to nearly any modern nation or civilization and be seen as accurate.

Demographic Transition Theory

  • Stage one of DTT is when a population is being formed and "pre-modern." Both birth and death rates are extremely high, 30-50 per thousand. This is due to lack of technology, low age-expectancy, high infant mortality rate, religious beliefs, need for workers, and lack of family planning. Death rates are high due to disease, famine, lack of clean water, war, competition for food, and lack of health care. Because the birth and death rates are similar, the population slowly increases.
  • Stage two of DTT presents itself when the death rate begins to decline at a rapid rate and the birth rate declines slowly. Urbanization and industrialization lead to healthier habitats, food, and the ability for people to live longer. Everything begins to improve and the death rate lowers, but the birth rate remains high. As the birth rate is still extremely high while the death rate rapidly declines, the population booms. It can double or triple in a single generation. Of the four confirmed stages, stage two and three account for the most population growth.
  • Stage three of DTT occurs when a nation is fully industrialized. The birth rate slowly approaches the death rate and the population continues to rise, but begins to stabilize. Jobs, food, housing, and medicine are all available.
  • Stage four of DTT is the fourth and final confirmed stage. This stage is manifested by low birth and death rates, and thus a stabilization of the population. This can be witnessed today in many countries around the world. The population is neither growing nor declining at a rapid rate, and the birth and death rates are roughly 10 per thousand (Montgomery).

As can be seen by this table, DTT quite accurately describes the transition of birth and death rates in the United States (death rates from 1800-1890 for the United States are not publicly available, and therefore are not included).

Approximate Date


Death Rate
































































(Deaths in the United States, 1900-2007) and (Fertility and Mortality in the United States)

The first four stages are a reliable model for countries that are transitioning through industrialization. The fifth stage however is not yet widely known. There have been however significant and important predictions about what happens once a country passes through the fourth stage. Many countries (United States, Sweden, Japan, Britain, and so on) that have already experienced their Industrial Revolution can be correctly described using DTT. It is for this exact reason that it is important to theorize about a fifth stage.

Stage Five

Today, developed or industrialized countries are in an idle state as far as populations are concerned. While our population periodically fluctuate, dipping and rising due to immigration, emigration, changes in fertility and the economy, in the end with rare exception are populations tend to balance out or decline over time. Speculation about what this means over time helps us to understand the importance of a fifth stage.

DTT was developed in the mid-1900, and no nation had passed through stage four. Today, many demographers believe that there are countries which have gone through stage four and are on their way to stage five, and there is a need to understand what that means.

We already know that a trend towards very low birth rate is going to be part of stage five. Part of the reason for this is the advancement and empowerment of women in the West. Sociologists commonly discussed some of the features of stage five societies with regard to the choices that women make to choose careers which means they are less likely to have children and how this will impact the overall fertility rate of the society. At the macro level this causes problems in a society as there are less workers available to fill needed jobs. At the micro level however this can be beneficial as new workers enter the workforce, unemployment rates decrease, and jobs are plentiful. In addition, at the micro level couple can benefit I having less children financially.

So you may be wondering why our population and populations in Western Europe continue to grow even though fertility continues to decline. The answer to this question is immigration. The effect immigration have on nation cannot be overstated. New cultures, cultural assimilation, and problems related to minority representation all come with immigration. Rapid and significant immigration can have both positive and negative effects on the host country and on the country that is losing its own citizenry.

Multiculturalism can create an atmosphere where people are open-minded but it can also play stresses on the system and on people who find it problematic to embrace newcomers and to adapt to the changes that newcomers bring. Often times immigrants choose not to assimilate, and instead isolate themselves and remain in enclaves of people who emigrate with them. This can create issues of conflict in our cities, and in our government.

In summary stage five of DTT can be both beneficial and detrimental to individual, groups, and the broader structure of society. Using sociology and multiple perspective allows us to pivot around the issues related to populations and to see it from multiple perspective, examining not only the benefit but also the problems that it can bring.

Using DTT as a Tool

For people who are going to work in areas where they have to understand populations, particularly those who might be working for government agencies or large nonprofit organizations, having a basic understanding of the 4/5 stages of DTT can be very helpful. Being able to examine a society's population and have an understanding of which stage that society fits into under DTT can help you if you need to prepare report about a particular country, it can help you brief somebody about a situation that might be happening somewhere around the world, and it can help you as a student have a better understanding of situations that are occurring globally.

Population Pyramids

A population pyramid is a visual representation of what a country's population looks like with regard to gender and age. It gives us an idea of the overall age distribution of the population and tells us an indication of reproductive capabilities of that population. Pyramids can tell us some very specific things about populations, and are another useful tool that you can incorporate into any job which requires you to have a basic knowledge of the composition of a particular population. You don't have to be a demographer or sociologist to gain benefit from using and understanding population pyramids.

There are three/four general types of pyramids:

Stable/Stationary Pyramids: these type show unchanging or low patterns of fertility and mortality

Stable Population Pyramid

Expansive Pyramids: these are very wide at the base and are indicative of high birth and death rates

Expansive Population Pyramid

Constrictive Pyramids: these type of pyramids come in at the bottom and they tend to be countries that have long life expectancies with low birth and low death rates (these are becoming more common and are typical of very developed nations).

Constrictive Population Pyramid

We can even use the concept of population pyramids to understand the stages of DTT:

Population Pyramids and DTT

Environmental Sociology

Toxic Los Angeles

One of the newest areas in the academic discipline of sociology is the study of environmental sociology which studies the relationship of how the environment influences and how we influence the environment. One of the biggest questions that environmental sociologists want to address is whether or not humans do have or should have the ability to behave differently than other animals on earth. Since we have the ability to reason at a high level, do we have an exemption from the laws that govern other life on earth? And do we have the right (or even an obligation) to manipulate resources to our advantage tinge? Finally who among us will be advantaged? Recognizing that some will be advantaged also forces us to recognize that some will be disadvantaged.

An important movement in the field of environmental sociology is that of environmental justice.

Just as we now know that a person's class can impact their life chances in many ways, so can their physical environment. One of the less obvious ways in which a person is impacted by class matters is where they live. Often, the poor live in areas which are more polluted and less environmentally and less physically safe than other areas. Environmental racism is "the disproportionate impact of environmental hazards on people of color." Defined, environmental racism is "inequality in the form of racism linked with environmental factors and processes that causes disproportionate stress on minority communities. Environmental racism is often used to describe specific policies, events, political maneuvers and outcomes which target minority communities for the placement of polluting industries and factories--further, it can be tied to the exclusion of minorities from the decision making process in their communities. Environmental justice is a movement in response to environmental racism. Read this interview with environmental sociologist Dr. Robert Bullard, who describes the beginning of the EJ Movement.

The most significant problems facing peoples of color are institutional and cultural racism which result in discrimination in access to services, goods and opportunities. Institutional racism involves polices, practices, and procedures of institutions that have a disproportionately negative effect on racial minorities' access to and quality of goods, services, and opportunities. Systemic racism is the basis of individual and institutional racism; it is the value system that is embedded in a society that supports and allows discrimination. Institutional and systemic racism establishes separate and independent barriers. Institutional racism does not have to result from purposeful action (human agency) or intention. Thus, racial discrimination can occur in institutions even when the institution does not intend to make distinctions on the basis of race.

In the context of racism, power is a necessary precondition for discrimination. Racism depends on the ability to give or withhold social benefits, facilities, services, opportunities etc., from someone who is entitled to them, and is denied on the basis of race, color or national origin. The source of power can be formal or informal, legal or illegal, and is not limited to traditional concepts of power. Intent is irrelevant; the focus is on the result of the behavior (

In recent years, environmental sociology has become a very popular field of study. While other sciences try to wrestle with the mechanics of environmental issues, sociology tries to shed light on the human element--that is to say, how are people impacted by the environment? The three major theoretical perspectives help us to pivot around the issue and see if from different points of view:

Environmental Theory

As we can see from these perspectives, issues about the environment don't exist until we identify them as such--for many years during the early Industrial Revolution in the West, urban centers had much worse air quality than many of our major cities do today--then, the air quality was considered an unfortunate byproduct of a changing world. Not until the last several decades has there been a concentrated effort by many groups and individuals to change the way we view air quality and air pollution. Environmental hazards are now viewed by most as something that must be mitigated in order for all groups, regardless of socioeconomic standing, to have the best possible quality of life.

Common Environmental Hazards

Oftentimes minority communities bear the brunt of environmental hazards due to their proximity to densely populated urban areas. According to the United States Environmental Protection Agency (EPA), a few of the most prominent examples of environmental hazards include the following:

  • Lead—There is a high concentration of lead problems in low-income communities where the public housing units were built before 1970.
  • Waste sites—Low income and minority populations are more likely than other groups to live near landfills, incinerators, and hazardous waste treatment facilities.
  • Air pollution—57% of all European Americans, 65% of African Americans, and 80% of Hispanic Americans live in communities that have failed to meet at least one of EPA's air quality standards.
  • Pesticides—Approximately 90% of the 2 million hired farm workers in the United States are people of color, including Chicano, Puerto Ricans, Caribbean blacks, and African Americans. Through direct exposure to pesticides, farm workers and their families may face serious health risks.

According to the U.S. Government Accountability Office (GAO), there is a statistically significant correlation between the location of hazardous waste facilities and the ethnic background of an area's residents. In predominantly minority areas, voter registration and education are often lower than average, and citizens are less likely to challenge proposals or seek financial compensation for environmental and health damages. Further, controversial projects are less likely to be sited in areas expected to pursue collective action. Some studies also suggest that the lack of protest could be due to fear of losing area jobs. Non-minority communities are more likely to succeed when opposing the siting of hazardous waste and sewage treatment facilities, incinerators, and freeways in their areas.

Watch this interview with Hilda Solis, former Secretary of Labor for the Obama Administration. While some social scientists see the siting of hazardous facilities in minority communities as a demonstration of intentional racism, others see the causes as structural and institutional. Again regardless of the intent, this is considered to be racism by definition. Processes such as suburbanization, gentrification, and decentralization lead to patterns of environmental racism even without intentionally discriminatory policies. For example, the process of suburbanization (or white flight) consists of non-minorities leaving industrial zones for safer, cleaner, and less expensive suburban locales. Meanwhile, minority communities are left in the inner cities and in close proximity to polluted industrial zones. In these areas, unemployment is high and businesses are less likely to invest in area improvement, creating poor economic conditions for residents and reinforcing a social formation that reproduces racial inequality.

What Groups are Impacted by Environmental Racism?

Many groups are impacted by environmental racism. Read this article, titled "Old Wine in a New Bottle" to get an overview of the problem. While environmental racism occurs worldwide, of particular importance to us in America are the effects of environmental racism on Native American Nations.

Effects on Native American Nations

In the past, the US Army, as sanctioned by the government, used several tactics to remove the Native Americans from their land. First, the American Bison was hunted almost to extinction in the 1870s--the Army encouraged these hunts to force Native Americans off their traditional lands and into reservations further west. The Indian Removal Act of 1830 and the Trail of Tears are also considered early examples of environmental racism in the United States. By 1850, all tribes east of the Mississippi had been removed to western lands, essentially confining them to "lands that were too dry, remote, or barren to attract the attention of settlers and corporations." Later, during World War II, military facilities were often located close to or aside reservations, leading to a situation in which a disproportionate number of the most dangerous military facilities in the US are located near Native American lands. More recently, Native American lands have been used for waste disposal by the United States and multinational corporations, but illegal dumping poses a greater threat.

What is the Environmental Justice Movement?

The term "environmental justice" (EJ) emerged in the US in the first part of the 1980s, and it was coined to bring light to the unequal distribution of burdens and benefits of our environment and resources where we live, work and play. Today, while many disciplines study the environment, sociology uses the EJ movement to study not only unequal distribution of resources in the natural environment, but also the impacts to classes in society. The US EPA (Environmental Protection Agency) defines EJ as "the fair treatment and meaningful involvement of all people regardless of race, color, sex, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations, and policies." One focus of the EJ movement is to seek redress due to unequal distributions of environmental burdens such as pollution, industrial facilities and crime.

The International Tribunal of Indigenous People and Oppressed Nations, convened in 1992, established to examine the history of criminal activity against indigenous groups in the United States, published a Significant Bill of Particulars outlining grievances indigenous peoples had with the U.S., including allegations that the United States "deliberately and systematically permitted, aided, and abetted, solicited and conspired to commit the dumping, transportation, and location of nuclear, toxic, medical, and otherwise hazardous waste materials on Native American territories in North America and has thus created a clear and present danger to the health, safety, and physical and mental well-being of Native American People."

Watch how some people have worked together to combat environmental racism:


As you can see, the social construction of issues related to the environment has largely been focused through the lens of conflict theory. Some groups have had more power than others, and thus have been able to influence and manipulate the environment to their own advantage--while disadvantaging other less powerful groups. Sociology helps us to bring into focus issues related to the environment from a HUMAN perspective. You are encouraged to do some additional investigating about the relationship between people and the natural world.


L'Allier, Stephen. "A Lesson on the Future of America's Population." 2013. Web. 20 Jan 2014.

Malthus, Thomas R. Malthus-Population: The First Essay. 1st ed. Ann Arbor, MI: University of Michigan, 1995. Print.