Demography is the study of human populations, including trends in fertility, mortality, age, gender, and population distribution. It also looks at criteria such as education, employment, religion, and ethnicity, and how these are distributed across populations, although these are generally studied on a more regional level. In 2022, the world’s population is approximately 7.9 billion people. China is the most populous country, with a population of almost 1.4 billion; however, India’s population is set to grow larger than China’s within a few years as it is at an earlier stage of demographic development, when growth rates tend to be higher.
The demographic transition
As societies industrialize or modernize, their populations undergo drastic changes. This process is known as the demographic transition – in simple terms this is where societies go from having high birth and death rates, to having low birth and death rates, and the interim period sees a sharp rise in population growth. This process usually begins with improvements in water sanitation and food production, as well as the implementation of widespread vaccination – these developments then lead to a large drop in mortality rates, especially among infants and children. In pre-industrial times, roughly a quarter of children did not make it to the age of one, and around half didn’t make it to adulthood – as child survival rates increase, populations grow exponentially. Because of this, life expectancy and the average age of the population also increase; therefore, population booms are rarely caused by a spike in birth rates, but because people live longer.
In fact, fertility rates fall during development, as mothers no longer need to compensate for child mortality and providing for larger families can become a burden. Demographic progress is generally accompanied by a significant improvement in opportunities for women and girls; domestic responsibilities lighten, creating opportunities for education, employment, and recreation, and women tend to have fewer children and at a later stage in life throughout this process. For society at large, these developments also coincide with a rise in prosperity and living standards; the amount of time needed for menial tasks is reduced, which creates more social and leisure opportunities, although there is also an uptick in many unhealthy lifestyle habits, such as smoking, imbalanced diets, and sedentary lifestyles.
In time, birth rates plateau at a relatively low level, in line with death rates, and this marks the end of the demographic transition in many countries. However, some countries’ demographic patterns have evolved differently thereafter, and imbalanced birth and death rates in regions considered among the most advanced (such as Germany and Japan) have led to natural population decline and rapidly aging populations.
Around 70 percent of the world lives in Asia and Latin America, and most of these countries are coming to the end of their demographic transitions, where population growth is slowing. Previous conceptions of so-called “developed” and “developing” societies are now being challenged, as countries such as Colombia, China, and Thailand have similar or higher life expectancies and lower fertility rates than the United States. Differences in economic or industrial maturity are no-longer reflected as strongly in demographics as they were in the 20th century.
Today, the region of Sub-Saharan Africa is considered the least demographically developed, but all countries are now progressing through their demographic transitions, and birth rates are falling rapidly across the region. In Europe and some parts of East Asia, aging populations coupled with low fertility is creating demographic crises. In countries such as Italy, Japan, and Portugal, the elderly population is roughly double the size of the young population, and this difference is set to become more pronounced in the future. Aging populations can place a strain on welfare and healthcare systems, as the need for elderly care infrastructure grows, and many families must invest more time and resources into caring for elderly relatives.
By 2100, the world’s population is expected to reach around 11 billion people, and almost all of this growth will be found in Sub-Saharan Africa. Africa’s development is progressing at a slower pace than the likes of South Asia or Latin America, as climate change is exacerbating the already-existing political, economic, and resource instabilities in the region. There are, of course, variations across Africa; the north and south of the continent tend to be more demographically developed than the regions in between; and countries such as Gabon, Ghana, or Kenya are more developed outliers in their respective regions. However, population growth in the least developed countries will drive future population development, with Nigeria set to have a population larger than all of Europe by the 2080s (today it is less than one third its size).
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