Over the past 100 years, the size and composition of the world’s population has been transformed. In 1930, the world was home to 2 billion people; on 21 January 1987 the world marked the birth of its 5 billionth citizen, taking 57 years to add 3 billon people; today (15 November 2022) the world population is estimated to reach 8 billion, taking just 35 years to add the next 3 billion.
The demographic forces behind this growth, i.e. increasing life expectancy followed later by a fall in birth rates, has also resulted in dramatic changes in the age structure of the population and in family structures. The timing of changes in deaths, then births, also results in population differences across the globe; the longer the delay in falling birth rates after death rates decline, the more rapid population growth. Demographers call this move from low life expectancy and high fertility, to high life expectancy and low fertility, the ‘demographic transition’.
Demographers have recognised for many years that as populations go through the demographic transition, kinship networks and associated systems of intergenerational support will change in both size and structure (Jian, 1995; Murphy, 2011). Improvements in infant and child mortality mean that more children survive to adulthood. Improvements in later age mortality mean that more adult children have surviving parents and grandparents, extending vertical kinship networks. In turn, falling fertility has meant that the size of generations is declining across cohorts. Whereas in the past a woman may have had five or six children, today she might only have one or two. Although these children stand a better chance of survival into adulthood than those in the past, there are, in general, smaller cohorts of adults of traditional working age available to support the growing number of elders. As well as fewer siblings, there are also fewer extended kin such as cousins, meaning that horizontal kinship networks are shrinking.
Intergenerational support as a driver of population change has received somewhat less attention and has at times been controversial. In 1976, in his seminal article on “wealth flows” theory, former IUSSP President ‘Jack’ Caldwell related demographic transition theory to changes in intergenerational transfers within the family. Caldwell argued that fertility would only fall in parts of sub-Sharan Africa when the flow of wealth from children to parents was reversed. His later work highlighted the key role of mass education through compulsory government programmes in achieving this (Caldwell, 1980). More recently, the notion of flows of support between the generations has again emerged as playing a critical role in fertility transitions – but this time in supporting higher fertility. For example, Miyazawa (2016) identified grandparental childcare as a key factor in household fertility production. A paper published this year in Genus reinforced this finding, with grandparental involvement positively associated with women’s labour force participation and fertility transitions (Rutigliano and Lozano, 2022).
Flows of support are complex and dynamic, with the receipt of parental help earlier in the life course influencing the likelihood of adult children reciprocating with support towards their parents later in life (Evandrou et al 2018). Thus, understanding patterns of intergenerational support is essential, particularly against the backdrop of changing family structures and global population ageing. So how might intergenerational support systems look in the future so that generations can work together?
- As vertical networks expand, individuals will spend a greater proportion of their life with three or more generations alive, first as children with grandparents and great grandparents and then in their own old age with grandchildren and great grandchildren. Moreover, as horizontal networks, e.g. siblings and cousins, shrink, the bonds between the generations may become tighter. Intergenerational flows of support that skip across one or even two generations - both downward and upward - will invariably become more common, e.g. grandparents contributing to education costs, grandchildren providing care, great-grandparents bequeathing the equity in their homes to great-grandchildren, missing out the middle two generations.
- As patterns of partnership change, demographers will need to widen their focus to include more complex non-biological kinship relationships including step-siblings, parents grandparents and grandchildren.
- To gain a truly comprehensive view of intergenerational support, demographers will need to move beyond kin to embrace other forms of intergenerational relationships, including friendship networks, neighbours and communities. Such relationships and associated flows of support may take on greater prominence where kinship ties are weakened, e.g. by lower proximity through increased international migration, or where vertical kinship networks are truncated e.g. through childlessness. One in five women born in the 1960s in the UK were childless at age 50, meaning that the number of women childless at age 80 will triple from around 20,000 today to over 60,000 in 2045.
- In the future, understanding support through the generations will require demographers to collect, analyse and interpret data across a wide array of networks, encompassing biological, non-biological and social kin.
Caldwell, J. (1976) Toward a restatement of demographic transition theory, Population and Development Review 2(3–4): 321–366.
Caldwell, J. (1980) Mass education as a determinant of the timing of fertility decline, Population and Development Review 6(2): 225–255. June 1980.
Evandrou, M., Falkingham J., Gomez-Leon, M., & Vlachantoni, A. (2018). Intergenerational flows of support between parents and adult children in Britain. Ageing and Society, 38(2), 321-351. https://doi:10.1017/S0144686X16001057
Jiang, L. (1995) Changing kinship structure and its implications for old-age support in urban and rural China, Population Studies 49(1):127-45.
Miyazawa, K. (2016) Grandparental child care, child allowances, and fertility, The Journal of the Economics of Ageing, 7: 53-60. https://doi.org/10.1016/j.jeoa.2016.03.002.
Murphy. M. (2011) Long-term effects of the Demographic Transition on Family and Kinship Networks in Britain Population and Development Review 37:55-80
Rutigliano, R., Lozano, M. (2022) Do I want more if you help me? The impact of grandparental involvement on men’s and women’s fertility intentions. Genus 78, 13. https://doi.org/10.1186/s41118-022-00161-x