The demographic changes apparent in societies result from the complex interaction of many factors with serious outcomes for development and mobility. Fertility rates are declining all over the world, dropping below the replacement threshold in some regions. Population distribution by age bracket shows a marked difference between the countries of the North and South.

The age structure of different societies around the world is conditioned by changes in the relationship between natural increase and net migration, which have a major impact on population growth and decline. The birthrate results from the more or less free choices of individuals, who in turn have many motives relating to economic and socio-cultural conditions, health, public policy (social provision for families, legal or ancestral prohibitions, the constraints of natalist or anti-natalist policies, direct or indirect financial support for families, etc.) and even the notion of family itself. Mortality is directly linked to peace, economic and sanitary conditions and public health, and also to natural disasters. Meanwhile migration is dependent on all these factors, starting with poverty and conflict. The tools for collecting all these data and the capacity for retrospective measuring vary from one country to the next and according to the highly complex demographic dynamics of each society, but broad trends can be identified. According to the United Nations Population, the total fertility rate for the whole world has gone from some 5 live births per woman in 1950-1955 to 2.5 births in 2010-2015. This change means that 46 % of the world’s population lives in countries where fertility has fallen below the replacement threshold (2.1 live births per woman), a figure expected to rise to 50 % in 2020-2025 and 75 % by 2030. In the 1990s, most countries in the world recorded remarkable progress in survival rates. While overall life expectancy at birth rose by 3.6 years between 2000-2005 and 2010-2015 (from 67.2 to 70.8 years), this was because the increase was faster in Africa (60.2 to 71.8 years). Today, when 42 % of the world’s inhabitants are under 25 (27 % in Europe and 60 % in Africa), the older population is growing faster than the population as a whole. Across the world, 962 million people were over 60 in 2017, twice as many as in 1980, and this figure is expected to double by 2050 (2.1 billion, including 425 million over 80).

Young and old, 2015

Source: Population Division - United Nations, World Population Prospects: The 2017 Revision,

Comment: The maps show reverse geographies: one of them specifies the proportion of under-15s in the population of states, while the second indicates the percentage of over-65s. These estimates – calculated for 2015 by the UN’s Population Division – show a sub-Saharan Africa in which young people represent over a third of the population. This is frequently the case in the Middle East also, which contrasts with North America, Eurasia, Northeast Asia, and Oceania, where there is a greater preponderance of older people in the populations. 

Old but still rich in the North

The steady growth in the numbers of older people in the societies of the North is the result of three long-term trends: fertility control, greater life expectancy and low levels of migration. A high standard of living, extensive systems of social protection, large numbers of women in the workforce and the spread of birth control have caused the birthrate to collapse, so that generations can no longer be replaced. Medical advances and access to health care have led to increased life expectancy. This boom in the numbers of older people, which was predictable though not anticipated, has turned Europe into the world’s oldest continent (35 % over 60). In a period that has seen the dismantling of the welfare state, low immigration and economic crisis, populations and individuals are facing major challenges in the economic, political, social, societal and family spheres, with rising health costs and a lack of support and care for the elderly, which in turn pose questions for end of life ethics and retirement provision.

People over 60 living with their children, 1990-2010 

Source: United Nations, Population division, 

Comment: Two-thirds of people aged over 60 live in developing regions and, throughout the world, half of over-60s live with their children. This global level masks strong regional differences: There are fewer than 20% living with children in North America and Europe compared with over 60% in Asia and Africa, where poverty allows no other solution than the cohabitation of generations.

The individuation of societies, family breakdown, urbanization, the housing crisis and the dissolution of social ties reinforce inequalities among older people. There is a growing divide between those who have access to the market in quality retirement homes and those who find themselves relegated to the margins and need help from charities in order to survive.

Evolution of the number of young and old, 1950-2050

Source: Population Division - United Nations, World Population Prospects: The 2017 Revision, 

Comment: The curves show the evolution, in millions, of the numbers of under-15s and over-65s, between 1950 and 2050, using projections of the UN’s Population Division. In the first ten countries, the increase in the number of older people is more sustained than among the younger population, confirming a general ageing trend. For young people, the strongest growth is in sub-Saharan Africa and South East Asia; while in emerging countries (Brazil, India, Indonesia and China) growth in the older population outstrips that of the North.

Still young and poor in the South

The increases in life expectancy that have begun to emerge in the South vary from one country to the next, and between social groups within a society. The persistence of diseases spread by infection or parasites and the proliferation and duration of situations of conflict are slowing and undermining these developments, notably in Africa. Though the birthrate is slowing everywhere, without social protection or access to contraception it remains very high in some places and, even when it falls, the age structure encourages births. The poorest regions and groups are those with the most children, adolescents and women.

Fertility Rates, 1950-2050 

Source: Population Division - United Nations, World Population Prospects: The 2017 Revision,

Comment: The curves show how fertility evolved between 1950 and 2015 with, for a few countries, projections up until 2050. Over the period under consideration, the number of children per woman fell everywhere. This trend can be observed in the countries of the North, which were already evidencing low levels in 1950 (Japan, Russia, United States, France); in those where the drop has already occurred (China, Brazil, India, Algeria), and in those where it is in progress/still to come (sub-Saharan Africa, including the Niger with 7 children per woman in 2015).

These poverty-driven demographic effects continue unchecked and are even increasing, generating greater needs for schools, health centers and jobs. UNICEF (United Nations Children’s Fund) estimates that, by 2030, 167 million children will be living in extreme poverty, 83 % of them in Africa. Countries with liberalized economies were pressured into cutting their spending and have suffered 10 years of economic crisis. They are unable to invest in the future of their young people, who have no option but to emigrate given the lack of training and jobs. The ageing of the population began in sub-Saharan Africa where, depending on the country, the proportion of old people is expected to double or even quadruple by 2050, leading to further difficulties for countries and families. China is in a singular demographic situation due to its one-child policy (1979-2015) and spectacular increases in life expectancy (from 40 years in 1949 to 76.5 in 2015). A very rapidly ageing society (135 million over 60 in 2015, 359 in 2050) in a context of massive urbanization, low incomes and low levels of social coverage could slow its economic expansion.

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