\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\) Show Learning Objectives
The variation of populations over time, also known as population dynamics, depends on biological and environmental processes that determine population changes. A population’s growth rate is strongly influenced by the proportions of individuals of particular ages. With knowledge of this age structure, population growth can be more accurately predicted. Age structure data allow the rate of growth (or decline) to be associated with a population’s level of economic development. For example, the population of a country with rapid growth has a triangle-shaped age structure with a greater proportion of younger individuals who are at or close to reproductive age. This pattern typically occurs where fewer people live to old age because of sub-optimal living standards, such as occurs in underdeveloped countries.  Changing Population Age Structure: This 3:28 minute movie discusses age structures and gives examples. Some developed countries, including the United States, have a slowly-growing population. This results in a column-shaped age structure diagram with steeper sides. In these cases, the population has fewer young and reproductive-aged individuals, with a greater proportion of older individuals. Some developed countries, such as Italy, have zero population growth. Countries with declining populations, such as Japan, have a bulge in the middle of their age structure diagram. The bulge indicates relatively-few young individuals, and a higher proportion of middle-aged and older individuals. Globally, less-economically developed countries in Africa and Asia have the highest growth rates, leading to populations consisting mostly of younger people. Improved health care, beginning in the 1960s, is one of the leading causes of the increased growth rates that created the population explosion. For example, in the Middle East and North Africa, around 65 percent of the population is under the age of 30. These high growth rates lead to the so-called “youth bulge,” which some experts believe is a cause of social unrest and economic problems such as high unemployment. Figure \(\PageIndex{1}\): Global percent growth rate of population: The percent growth rate of population in different countries shows that the highest growth rates are in underdeveloped regions of Africa and Asia.All of the factors above also have an impact on the average life expectancy. As economic development and quality of health care increase, the life expectancy also increases. Figure \(\PageIndex{1}\): Worldwide Life Expectancy by Country: 2012 map showing average life expectancy by country in years. In 2012, the World Health Organization estimated the average global life expectancy as 70.5 years.Key Points
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Contributions and Attributions
This page titled 45.4C: Age Structure, Population Growth, and Economic Development is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Boundless. What does an aging population look like on a population pyramid?Constrictive. Constrictive population pyramids are used to describe populations that are elderly and shrinking. Constrictive pyramids can often look like beehives and typically have an inverted shape with the graph tapering in at the bottom.
What does an age structure diagram shaped like a pyramid indicate?An actual “pyramid” shape age structure – a graph with a wide base and narrow top – is said to be expanding. This triangular shape reflects a growing, or expanding, population. A rectangular shape age structure – mostly similar width from bottom to top of the graph – is stable.
What is true about a population pyramid?Which of the following is true about population pyramids? They express the ages and population numbers of a group of people.
What is a population pyramid that is in the shape of a triangle likely to represent?The first is when there are both high fertility and high mortality rates among younger members. This type of population, known as “expansive,” creates a sharp triangle shape in the graph. Expansive pyramids mean that the population does not increase much in total number and has many young people.
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What is likely to be true of a population with an age structure that is pyramid shaped?
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