CC BY 4.0<\/a><\/span><\/figcaption><\/figure>\nThomas Malthus (1766\u20131834) was an English clergyman who made dire predictions about Earth\u2019s ability to sustain its growing population. According to Malthusian theory<\/strong>, three factors would prevent human population from exceeding the earth\u2019s carrying capacity<\/strong>, or how many people can live in a given area considering the limited amount of available resources. He identified these factors as war, famine, and disease (Malthus 1798). He termed these \u201cpositive checks\u201d because they increased mortality rates, thus keeping the population in check, so to speak. He contrasts these with \u201cpreventive checks,\u201d including birth control and celibacy, which also seek to control the population, but by reducing fertility rates.<\/p>\nIn his Essay on the Principle of Population<\/i>, (1798) Malthus argued that the production of food could only increase arithmetically (ie., 2, 4, 6, 8\u2026)<\/span><\/span> , while, unchecked, the population would increase at an exponential rate (ie., 2, 4, 16, 132\u2026)<\/span><\/span>. Eventually, this meant that people would run out of food and begin to starve. They would go to war over the increasingly scarce resources, reduce the population to a manageable level, and the cycle would begin anew.<\/p>\nOf course, this has not exactly happened. The human population has continued to grow long past Malthus\u2019s predictions. So, what happened? Sociologists suggest three reasons for the continued expansion of the population of our planet. First, technological developments in food production have increased both the amount and quality of calories produced per person. Second, scientific advances have developed new medicines to curtail death from disease. Finally, the development and widespread use of contraception and other forms of family planning decreased the speed at which the population increased. But what about the future? The thesis that catastrophic overpopulation will exceed the carrying capacity of the planet is still based on the Malthusian theory. In this model, ample resources to support the Earth\u2019s population will soon run out, leading to a dismal apocalyptic future of war, famine, and disease.<\/p>\n
Zero Population Growth<\/h2>\n
A Neo-Malthusian researcher named Paul Ehrlich brought Malthus\u2019s predictions into the 20th century. However, according to Ehrlich, it is the environment, not specifically the food supply, that will play a crucial role in the continued health of planet\u2019s population (Ehrlich 1968). His ideas suggest that the human population is moving rapidly toward complete environmental collapse, as privileged people use up or pollute a number of environmental resources, such as water and air. He advocated for a goal of zero population growth<\/strong> (ZPG), in which the number of people entering a population through birth or immigration is equal to the number of people leaving it via death or emigration. While support for this concept is mixed, it is still considered a possible solution to global overpopulation.<\/p>\nCornucopian Theory<\/h2>\n
Of course, some theories are less focused on the pessimistic hypothesis that the world\u2019s population will meet a detrimental challenge to sustaining itself. Cornucopian theory<\/strong> scoffs at the idea of humans wiping themselves out; it asserts that human ingenuity can resolve any environmental or social issues that develop. As an example, it points to the issue of food supply. If the population needs more food, the theory contends, agricultural scientists will figure out how to grow it, as they have already been doing for centuries. In this perspective, human ingenuity has been up to the task for thousands of years and there is no reason for that pattern not to continue (Simon 1981).<\/p>\nDemographic Transition Theory<\/h2>\n
Other sociologists argue there are clear patterns that can be seen in population growth that show that rapid or exponential population growth is a temporary phenomenon. Modernization theorists argue that societies develop along a predictable continuum as they evolve from unindustrialized to postindustrial societies. Following the modernization thesis, demographic transition theory<\/strong> suggests that future population growth will develop along a predictable five-stage model (Caldwell and Caldwell 2006) .<\/p>\n <\/p>\n![\"The](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Demographic-Transition-Theory-1024x812.png\")
Figure 20.9<\/strong> The five stages of the demographic transition. In the top graph, high birth and death rates with a low population total represent Stage 1. High death rates cancel out high birth rates, and the population remains low and stable. As demographic transition occurs, death rates decline due to the introduction of modern medicine and public health measures, while birth rates remain high, leading to rapid population growth. As birth rates decline to match lower death rates, population growth stops or declines. This is represented in the population pyramid shapes, which go from steep pyramidal, based on a high ratio of children to adults, to oval, based on similar population levels at each age range until around 70. (Figure courtesy of Max Roser\/Wikipedia Commons.) CC BY-SA 4.0<\/a><\/span><\/figcaption><\/figure>\nIn Stage 1, birth, death, and infant mortality rates are all high, while life expectancy is short. An example of this stage is 19th century North America. As countries begin to industrialize, they enter Stage 2, where birth rates are higher, and infant mortality and death rates drop. Life expectancy also increases. The Congo is currently in this stage. Stage 3 occurs once a society is thoroughly industrialized; birth rates decline, while life expectancy continues to increase. Death rates continue to decrease. Mexico\u2019s population is at this stage. Stage 4 is the postindustrial era of a society. Birth and death rates are low, people are healthier and live longer, and society enters a phase of population stability or even decline. Sweden and Canada are considered Stage 4. Stage 5 projects future demographic transition as uncertain. Some predict continued declining populations, but others note a slight uptick in fertility rates in post-industrial societies, coupled with potential leaps in life expectancy due to advances in medical technology.<\/p>\n
Current Global Population Trends<\/h1>\n
As mentioned earlier, the Earth\u2019s population is over 8 billion. That number might not seem particularly jarring on its own. But consider the fact that the human population grew very slowly for most of its existence, then doubled in only half a century to reach 6 billion in 1999. Now, just over twenty years later, it has added another two billion.
![\"Shoulder](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/08\/Crowd-1024x512.jpg\")
Figure 20.4<\/strong> Earth\u2019s population, which recently grew to 8 billion in November 2022, could reach 9.7 billion by 2050 (UN, 2022). (Photo courtesy of Scott Cresswell\/Flickr.) ![\"Population](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/growth-rate1-300x204-1.png\")
<\/a> Figure 20.5<\/strong> Population growth rate (Image courtesy of Sydney Brown\/Khan Academy.) CC BY-NC-SA 2.0<\/a>[\/caption]\r\n\r\nThe growth rate <\/strong>of a population, or how the population of a defined area grows or shrinks in a specific time period, is therefore a function of the number of births and deaths, as well as the number of people migrating to and from a country. It is calculated as the current population minus the initial population (at the beginning of the time period) divided by the initial population (then multiplied by 100). This gives the percentage increase relative to the initial population.\r\n<\/span>\r\n\r\nFor example, Canada's growth rate in 2022 was 2.7%, the highest among the G7 countries (as has been the case for several years), and highest since 1957 when the growth rate was 3.3% (Statistics Canada, 2023a). The reason for population growth was much different than in 1957. In 1957, the record high growth rate was due to the increased number of births during the post-war baby boom, as well as the immigration of Hungarian refugees following the Hungarian Revolution of 1956. In 2022, immigration was the sole cause of population growth, with 95.9% of the growth due to the arrival of approximately one million international immigrants. Canada is otherwise a low fertility country, with a record low of 1.40 children per woman in 2020 \u2014 far below replacement level (Statistics Canada, 2022). Canada's population hit 40 million people in 2023 (Statistics Canada, 2023b).\r\n![\"A](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Canada-population-pyramid.png\")
Figure 20.6<\/strong> This population pyramid shows the breakdown of the 2020 Canadian population according to age and sex. (Graph courtesy of PopulationPyramid.net.) ![\"A](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Democratic-Republic-of-Congo.png\")
Figure 20.7<\/strong> This population pyramid shows the breakdown of the 2020 population of the Democratic Republic of the Congo according to age and sex. (Graph courtesy of PopulationPyramid.net.) ![\"Black](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Malthus-246x300.jpg\")
Figure 20.8<\/strong> Thomas Malthus (1766-1834) by John Linnell (1834) (Image courtesy of Wellcome Collection Library\/Wikimedia Commons.) ![\"Graph](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Global-Population-1-1024x588.png\")
Figure 20.10<\/strong> Global population has steadily increased since 1950 and will continue to do so, even as the population growth rate has declined. \"Given that most population increase until 2050 will be driven by the momentum of past growth, further actions by Governments aimed at reducing fertility would do little to slow the pace of growth between now and mid-century, beyond the gradual slowdown indicated by the projections presented here\" (Graph courtesy of ![\"The](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Figure_20_01_04-e1413823706909.png\")
Figure 20.11<\/strong> Projected Population in Africa. This graph shows the population growth of countries on the African continent, many of which have high fertility rates. (Graph courtesy of USAID, 2010.) ![\"A](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/canada-population-estimates.gif\")
Figure 20.12<\/strong> Projected Population in Canada. Canada has a low fertility rate, and therefore, a comparatively moderate projected population growth. (Graph courtesy of USAID, 2010.) ![\"This](\"https:\/\/opentextbc.ca\/hfriedmantext2\/wp-content\/uploads\/sites\/440\/2023\/09\/Figure_20_01_06-e1413823693369.png\")
Figure 20.13<\/strong> Projected Population in Europe. This chart shows the projected population growth of Europe for the remainder of this century. (Graph courtesy of USAID, 2010.)