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Journal of Population Sciences

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Review of How Population Change Will Transform Our World by Sarah Harper


In this book, Sarah Harper explores the relevant topic of the shift in the age structure of the world’s population. She addresses this issue by considering the entire world population. In particular, she deeply analyses causes and consequences of the age-structural change highlighting convergences and differences between populations of various geographical areas and focusing on the connections with economic and social factors. Addressed also to a wider audience, this book sheds light about the important changes of the population age structure and about the future of the world population. The author highlights differences and interconnections existing between various populations of the world, without forgetting to stress the importance to consider changes at the individual level within the society. Sarah Harper, through this book, contributes to provide instruments and knowledge to understand the populations and societies of the world.

In this book, Sarah Harper explores an extremely relevant topic, the shift in the age structure of the world’s population and its future implications. As she writes at the beginning of her work, while changes in the population size after the demographic transition were well studied and documented, modifications in the age structure and their social and economic implications were less discussed and understood. This is particularly true at the level of public opinion. The author addresses this issue with scientific strictness but at the same time adopting a style and a narrative able to attract a wide audience. She deeply analyses causes and consequences of the age-structural change highlighting convergences and differences between populations of various geographical areas and focusing on the connections with economic and social factors. The relation between economic growth and population growth has been often studied and analysed; however, as Harper shows in this work, the changes in the age structure can play a major role in the economic and social evolution of the populations.

Harper begins the first chapter presenting three different demographic regimes: advanced economies (European and North American countries, Australia, New Zealand and Japan), with populations characterized by a low percentage of young people and a growing proportion of older people; emerging economies (Asian, Latin America countries and North African countries), with populations composed by a large proportion of young people and adults; and least developed economies (few Asian countries, sub-Saharan Africa), with populations characterized by the presence of a large percentage of children and adolescents. She explains the phases of the demographic transition, the different timing and evolution of the demographic drivers which have shaped the age structure of the populations of these regimes. Here, the author immediately introduces an element able to attract the attention of non-experts. She describes the story of three women born in the same year, 1975, in three different countries, Niger, Malaysia and Italy. Through this incursion into the lives of these women, Harper marks the connection between individual lives and what happens at the societal level and also the influence that different social, cultural, economic and demographic factors can have on single lives. By doing so, she underlines the importance that demography has in shaping our individual lives, beyond showing the differences between three different populations and societies.

In the second chapter, Harper analyses the causes of mortality and birth decline highlighting the dissimilarities between the demographic regimes. Differently from the advanced economies, in the emerging and least developed economies, the transition from high to low mortality rates was driven from sanitation and medical innovation transferred from abroad. Therefore, their transition was faster and incomplete and, especially in the least developed economies, the infectious diseases are continuing to cause deaths. In the same countries, fertility has very high and stalling levels, while in emerging economies the transition from high to very low fertility has been even faster than in advanced economies. From these dynamics arise different challenges: very low fertility and extreme longevity in European and some Asian countries, which will emphasize population ageing process, high levels of fertility and mortality and morbidity in the least developed economies, especially in sub-Saharan countries. The author deeply analyses these specific challenges in the subsequent four chapters providing relevant suggestions for future action.

The third chapter is dedicated to the population ageing process, determined by continuing fertility decrease and life expectancy increase. As Harper writes, despite this process will concern many of the advanced economies, there is still confusion about the modalities and consequences. Harper contributes to shed light on this process by deeply analysing the connections between ageing, production, consumptions and savings. Indeed, the main concerns connected to the population ageing are related to the increase in the expenditures for public pensions and health care systems and to the possible reduction of consumption. Individuals produce, consume and save in different ways throughout lives, and in modern societies, older people tend to consume more than they produce since they receive pensions and long-term care. Despite Harper highlights the relevant contribution that old people have given to the societies during their lifetimes through taxes, savings and familial supports, she outlines that an increasing number of pensioners could create economic problems. Furthermore, increasing longevity can lead to the diffusion of chronic diseases and to intensify the pressure on national health systems. The ageing process of numerous cohorts will cause an increase of persons living the moments close to death; those people will also cause the increase of health costs. The declining number of young people will affect the ability of the society to provide workers to care for disabled old people and to finance the national health system through taxes. One of the major challenges connected to the population ageing is the difficulty to know whether an increase in the number of lived years will lead to an increase in the number of years spent in good health or an increase in those spent in disability. However, according to the author, all the problems connected to population ageing challenge depend on how societies and populations are organized. The institutional frameworks and societal organization can be the key to create a second demographic dividend. Some old workers may choose to continue to work, and longer life could allow to accumulate assets over a longer period of time. Different weights of public transfers and different typologies of retirement can lead to new levels of consumption and production. However, in order to make this possible, institutional and financial structures have to be developed.

In the fourth chapter, the author deals with the major challenge of the emerging economies, namely the youth bulge, the large proportion of cohorts between 15 and 24 years old in relation to the rest of the population. As Harper writes at the beginning of this chapter, despite half of the total population of the world is aged less than 25 years, the majority of the actual workers are not young people. On the opposite, young people have a higher likelihood to be unemployed and inactive. If the increase of young people does not match the increase of the employment opportunities, the risks of political instabilities and criminal activities could increase. Countries such as the Asian Tigers have capitalized the presence of large generations of young adults and experienced the demographic dividend, characterized by the presence of large generations in active age, contextual decrease of dependent children and relevant economic growth. However, in order to benefit from the demographic dividend, the economic and institutional context needs to show some positive characteristics, such as an efficient financial system, flexibility in the labour market, investments’ policies and a skilled working population. So, there are numerous drivers: the demographic ones, as the increase in the working age population, but also the economic ones, such as investments in human capital, increase in female activity rate and incentives to save. Countries which are going to face this challenge are, in particular, the MENA countries, with the highest percentage of young generations. On the one hand, the youth bulge represents an opportunity for the economic growth; on the other hand, it can represent a huge challenge. The lack of social and economic structures can turn the demographic dividend into a potentially dangerous phenomenon for the society, especially if the societies are not able to provide full employment for these large segments of young population.

The fifth chapter is devoted to the discussion of the principal challenge of the least developed economies: i.e. the presence of a large proportion of children and adolescents socially dependant. Considering the actual large proportion of young adults and the childbearing levels in these countries, population will continue to grow and children will continue to constitute a large part of the population. Because of the demographic inertia, this will happen even if fertility rates will significantly decline in the upcoming years. Today, in sub-Saharan Africa, many countries are rather experiencing a stall in the fertility decrease. There are several factors behind such phenomenon, such as the lack of long-term care programmes, poor family planning programmes, the economic advantage of having children and the preference for large size families in some communities. Unfortunately, the large number of children and adolescents in Africa is contributing to slow down the economic growth and reduce the possibility to experience a demographic dividend. Young working population needs to transfer much of their own income to children, while the participation of women in the labour force is still really low. Furthermore, the large public investment in human capital of very young people, through education and health, cannot be maintained because of the high dependency rate that children have on the workers. A demographic dividend in these countries can be experienced only through a significant fertility drop. In turn, this can be achieved with more investments in family planning and reproductive health programmes. Female empowerment is also a key to slow down population growth: girls and women can play an important role, since they are primarily responsible for health, immunization and nutrition of children in several communities. As Harper writes, several studies have pointed out that mothers’ education represents the most important determinant of infant mortality (e.g. Alemayehu et al. 2015, Anyamele et al. 2017, Gayawan et al. 2016). However, barriers to female education and gender equality are still very high. Finally, the least developed countries have difficulties to satisfy the demand for education, because of the lack of funding and teachers and because families are unable to sustain the costs of educating their children.

In the sixth chapter, Sarah Harper summarizes the principal conclusions of her work, by adding some further consideration about the age-structural shift of the world population. Before drawing her conclusions, she discusses the role of population policies addressing their effectiveness and providing examples of direct and indirect policies which could contribute to influence some demographic components, such as fertility and migration. She then discusses how demographic changes interact with two major challenges of this century, the environmental change and technological advance, highlighting how this interaction poses further challenges for the economies. In this final chapter, Harper stresses the importance of studying and considering changes in the population age composition. According to her, the age-structural change counts just like economic and political changes for the development of the countries. Paths of future regional development can be explained and understood only by recognizing the interconnection between age-structural change and economic, social and political institutions. As she often states in the book, despite the demographic, social and economic differences, all the populations will face the same challenge: to ensure individual wellbeing to all the persons, by reducing inequalities between individuals and between different generations. This and other challenges need to be addressed with new tools and institutions able to substitute the old ones of the previous century. New national and international policy-making should integrate the age-structural change issue.

The strength of this work is to address a relevant issue, the change of the age composition, by considering the entire world population. Sarah Harper deeply describes the principal causes and consequences of the different paths of change in the age structure in the different populations of the world. She highlights differences but also similarities and interconnections existing between various populations of the world, without forgetting to stress the importance to consider changes at the individual level within the society. She describes all the particular challenges that the age-structural shift poses to the different populations, but at the same time, she shows how this change can be considered as a universal challenge, identical through different populations and societies. With this book, Harper sheds light about the future of the world population by showing aspects often neglected in the public discourses within the societies. Addressed to a wider audience, this book should be read to understand populations in which we are living, our societies and how to face the future challenges and to exploit the opportunities of demographic changes.

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Correspondence to Sara Miccoli.

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Miccoli, S. Review of How Population Change Will Transform Our World by Sarah Harper. Genus 76, 5 (2020).

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