Codex Populi

Research chronicle

Papers, preprints, data releases, and policy documents related to the indicators in this dataset, gathered daily and summarized by AI.

Country
Indicator
Type
Preprintcrossref-catchall9/29/2026

A Budgeted Robust Cohort-Transition Model for Enrollment Capacity Planning Under Demographic Decline

AI summaryThis paper presents a budgeted robust cohort-transition model for planning university enrollment capacity amid demographic decline, integrating lagged demographic indices with robust optimization to handle uncertainty in intake and retention across four-year and two-year entry routes. Using a public-data case study anchored to a 20,073-undergraduate reference, it projects 2043 enrollment at 12,067 under nominal conditions and 11,357 under a robust lower envelope, showing that deterministic or delayed-start plans incur substantial FTE shortfalls compared to a least-cost robust plan, while derating capacity limits by 20% preserves feasibility across simulated draws at a 36% cost increase. The authors frame these findings as conditional planning trade-offs rather than validated forecasts, noting that predictive validation at the grade level remains unavailable.

Abstract

Demographic contraction reaches university admissions with a long delay and propagates through enrollment stocks of different durations. We integrate lagged demographic indices, cohort transitions and budgeted robust optimization to plan ramp-constrained incremental educational activity. The formulation uses a lower enrollment envelope for an activity floor and an upper envelope for resource protection while jointly propagating intake uncertainty and retention stress. A public-data case distinguishes four-year direct entry and two-year transfer routes around a 20,073-undergraduate reference. Under stated assumptions, nominal enrollment in 2043 is 12,067 and the lower envelope at uncertainty budget two is 11,357; an 85% activity floor requires 5705 peak incremental full-time equivalents (FTEs). Under the same envelope, deterministic and delayed-start plans produce 1046 and 4474 cumulative FTE-years of shortfall. Because the least-cost plan attains its ramp and capacity limits, operational draws that tighten a binding limit require re-planning; planning with those limits derated by 20% keeps the unchanged schedule feasible in all 1000 draws at 36% higher cost. Convergence checks, structural scenarios and public-record reconstructions support verification, but grade-level predictive validation remains unavailable. The results are conditional planning trade-offs, not validated forecasts or guarantees of participation in new programs.

Preprintnber9/28/2026

Optimal Population Growth in the Diamond OLG Model -- by Laurence M. Ball

AI summaryThis paper by Laurence M. Ball examines how population growth affects welfare in an OLG model, noting that slower population growth raises output per worker while lowering the ratio of workers to retirees. Under mild parameter restrictions, an optimal population-growth rate exists that maximizes steady-state welfare, and this rate could be negative, implying population shrinkage may be optimal. The analysis also shows that introducing a pay-as-you-go social security system lowers the optimal population-growth rate.

Abstract

This paper studies the effects of population growth on welfare in an OLG model, in which lower population growth raises output per worker but also reduces the ratio of workers to retirees. Under fairly mild restrictions on the model’s parameters, there exists an optimal population-growth rate—one that maximizes steady-state welfare. This growth rate may well be negative: it may be optimal for the population to shrink over time. The introduction of a pay-as-you-go social security system reduces the optimal population-growth rate.

Papernber9/28/2026

Does Fertility Stabilize At Low Levels? Evidence from Period, Cohort, and Subnational Data -- by Diane Coffey, Michael Geruso, Dean Spears, Sangita Vyas

AI summaryThis paper examines whether fertility rates stabilize at low levels, challenging assumptions in many population projections that fertility will rebound or reach equilibrium once it falls low. Using UN period data (1950-2023), Human Fertility Database cohort data (1935-1975 across 31 countries), and subnational data from Japan, India, and the US, the authors find no robust evidence of a systematic rebound or stable equilibrium; instead, fertility tends to keep declining once it becomes low. The findings reconcile earlier reports of fertility reversals in some countries during the early 2000s and suggest a need to reexamine equilibrium and rebound assumptions in widely used population projections.

Abstract

Many population projections used by international and government agencies assume that, in today's low-fertility societies, future fertility rates will stop declining and roughly stabilize. This paper assesses the evidence for an equilibrium point or rebound from low levels. We show that there is no robust evidence for a systematic fertility rebound, or for a stable equilibrium point at any fertility level conventionally assumed. Instead, where and when fertility has fallen low, it has tended to keep falling. This is true across a range of data sources, time periods, and fertility measures: United Nations data on period total fertility rates for all country-years from 1950 to 2023; Human Fertility Database data on completed fertility for cohorts born between 1935 and 1975 in 31 countries; and fertility rates in subnational geographies in Japan, India, and the United States. We reconcile these results with a prior literature that documented fertility reversals among some low-fertility countries in the early 2000s. Our findings provide an empirical basis for re-examining the equilibrium and rebound assumptions embedded in widely used population projections.

Papernber9/28/2026

Terra Incognita: The Economics of a Shrinking World -- by Jesús Fernández-Villaverde, Patrick Norrick

AI summaryFernández-Villaverde and Norrick argue that humanity has likely fallen below replacement fertility for the first time, with declines concentrated in low- and middle-income countries and among poorer, less educated women. Using a single-factor model across 236 countries since 1950, they find a common fertility component peaked in 1978, while country-specific negative trends now dominate, none leveling off; they attribute this to modernity making additional children costly and childlessness cheap, with no economic mechanism pushing fertility back up. They conclude by outlining economic consequences, notably slower growth.

Abstract

As of 2026, humanity is likely below replacement fertility. That has never happened before, not in wars or pandemics. But the real surprise is that the fall has been concentrated in low- and middle-income countries and among poorer and less educated women. We fit a single-factor model to 236 countries since 1950: the common component peaked in 1978, and what drives fertility down today are country-specific trends, 219 of them negative and not one leveling off. None of the commonly cited mechanisms can account for this pattern, so we offer a conjecture: modernity itself, which makes a third child expensive and childlessness cheap. Children come in integers, so it takes very little to move a cohort’s fertility rate from 1.8 to 1.3. And nothing in an economy pushes fertility back to 2.1. We close with the main economic consequences, in particular slow growth.

Papercrossref-catchall9/25/2026

Can AI Sustain Long-Run Growth Amid Demographic Decline?

AI summaryThis paper develops a semi-endogenous growth model examining whether AI can offset the effects of declining population growth by acting as a scalable input in idea production alongside human researchers. It shows that outcomes depend critically on the elasticity of substitution between AI and human research labor: complementary AI boosts growth but remains bound by demographic limits, while sufficiently substitutable or rapidly improving AI can relax these constraints, potentially leading to explosive growth above a critical knowledge threshold. The authors conclude that AI's long-run growth impact hinges on measurable factors like R&D substitutability and knowledge accumulation returns rather than AI's label itself, emphasizing policies that expand these underlying mechanisms.

Abstract

Can artificial intelligence (AI) sustain economic growth as population growth slows or turns negative? We study this question in a semi-endogenous growth framework in which AI enters the production of ideas as a scalable input alongside human research labor. The key object is the elasticity of substitution between AI and researchers. When AI is complementary to human research labor, it can generate large and persistent level effects and accelerate growth over policy-relevant horizons, but demographic constraints continue to bind asymptotically. When AI is sufficiently substitutable for researchers, or when AI capabilities improve sufficiently rapidly, the model admits qualitatively different regimes in which AI can relax demographic constraints and, under stronger feedback, generate explosive dynamics. Under population decline, reinforcing knowledge feedback can also generate a critical initial-knowledge threshold: economies above it can enter explosive AI-assisted growth, whereas economies below it converge to a finite terminal stock of knowledge. The framework therefore reconciles two prominent views of AI: AI as an amplifier of human discovery and AI as a potentially transformative substitute for human research effort. We also allow AI investment to be chosen endogenously and examine alternative specifications for AI accumulation and recursive improvement. Across these cases, the long-run consequences of AI depend less on the label "AI" itself than on measurable economic objects-substitutability in R&D, returns to knowledge accumulation, and the scalability of AI capability. The results highlight the importance of policies that expand the effective

Papercrossref-catchall9/24/2026

Population Dynamics and Demographic Crises in the Parish of Detva (1781–1920): Evidence from Inverse Projection

AI summaryThis study uses inverse projection applied to parish registers (58,551 baptisms and 39,032 deaths) to reconstruct population dynamics in the rural parish of Detva, Slovakia, from 1781 to 1920. It finds gradual population growth interrupted by crises from epidemics, famine, and emigration, with high fertility and low life expectancy (~32 years) persisting until late 19th-century economic and wartime pressures triggered decline. The research demonstrates that Detva's demographic regime remained largely pre-transitional, highlighting the utility of parish records for reconstructing population history in pre-statistical Central European settings.

Abstract

This study provides a comprehensive historical demographic analysis of the parish of Detva, located in present-day Slovakia, covering the period 1781–1920. It aims to reconstruct long-term population dynamics and assess the determinants of demographic change in a rural Central European setting, where systematic census data are limited. Parish registers of births, deaths, and marriages serve as the primary sources, with a total of 58,551 baptisms and 39,032 deaths analysed to reconstruct population dynamics. The study applies the inverse projection method, enabling the estimation of population size, age structure, fertility, mortality, and other key demographic indicators in a context where census data are incomplete or unavailable. The results reveal that the parish experienced gradual population growth, punctuated by periods of crisis caused by epidemics, famine, economic instability, and emigration. Crude Birth and Death Rates, along with Gross and Net Reproduction Rates (GRR and NRR), indicate sustained generational replacement, with fertility remaining high until the late 19th century and only declining under the influence of economic and wartime crises. Life expectancy at birth (e_0) remained relatively low, averaging around 32 years, reflecting high mortality among children and the elderly before the demographic transition. The age structure was dominated by children and young adults, while the oldest age groups were consistently underrepresented due to high mortality. These findings suggest that the demographic regime of Detva remained largely pre-transitional well into the late 19th century, with only partial and delayed responses to broader socio-economic transformations. This research highlights the complex interplay of economic, social, and epidemiological factors in shaping population dynamics in a rural Slovak parish. The findings contribute to a deeper understanding of historical demographic processes in Central Europe and demonstrate the value of parish registers and model-based reconstructions for studying populations in pre-statistical periods.

Preprintcrossref-catchall9/23/2026

Demographic Change and Life Expectancy in Nigeria: Assessing the Effects of Fertility, Infant Mortality, Population Growth and Net Migration

AI summaryThis study uses ARDL modeling on 1991-2025 Nigerian time-series data to examine how fertility rate, infant mortality, population growth, and net migration affect life expectancy, finding a stable long-run relationship among these variables. Fertility rate showed a positive effect (cautiously interpreted as reflecting broader healthcare and socioeconomic improvements), while infant mortality and population growth had significant negative effects, and net migration's negative effect was statistically insignificant. The authors recommend strengthening maternal and child healthcare, expanding primary healthcare coverage, and promoting family planning to improve longevity, while suggesting future panel-data research to address endogeneity.

Abstract

This study investigates the effects of fertility rate, infant mortality rate, population growth rate, and net migration on life expectancy in Nigeria over the period 1991-2025. The study was motivated by limited empirical evidence on the combined influence of key demographic variables on longevity despite their importance for health and development policy. Annual time-series data were analysed using the Autoregressive Distributed Lag (ARDL) approach following Phillips Perron unit root tests and ARDL bounds cointegration analysis. The results confirmed the existence of a stable long-run relationship among the variables. Fertility rate exerted a positive and statistically significant effect on life expectancy, whereas infant mortality rate and population growth rate exhibited significant negative effects. Net migration showed a negative but statistically insignificant relationship with life expectancy. Diagnostic tests revealed no evidence of serial correlation or heteroskedasticity, while normality, specification, and stability tests confirmed the robustness and reliability of the estimated model. The findings suggest that demographic characteristics remain important determinants of life expectancy in Nigeria. The unexpected positive fertility coefficient is interpreted cautiously because it may reflect improvements in maternal and child healthcare, broader socioeconomic progress, and unobserved structural factors rather than a direct beneficial effect of higher fertility. The study concludes that sustained reductions in infant mortality and effective population management are essential for improving longevity. It recommends strengthening maternal and child healthcare services, expanding primary healthcare coverage, promoting voluntary family planning and reproductive health education, and improving demographic data systems. Future research should employ panel datasets to address endogeneity in Nigeria.

Preprintnber9/21/2026

Compound Delay: The Causes and Consequences of Later Grandmotherhood -- by Dora L. Costa, Matthew E. Kahn

AI summaryThis study examines how successive generations delaying first births compound to push median age at first grandmotherhood from 44 (under the 1960 fertility schedule) to 57 (under 2024 patterns), sharply reducing healthy years available for grandmothers to provide care and financial support to grandchildren, even as overall lifespans lengthen. The delay is most pronounced among college-educated women, with access to reproductive control explaining over half the decline in grandmotherhood by age 55 among White college graduates, and the authors frame this as a "Rotten Adult Kid Problem," where daughters' birth-timing decisions impose external costs on their mothers while raising both the price of grandmother care and wealth per grandchild.

Abstract

We show how fertility delays compound across generations to raise age at first grandmotherhood. Under the 1960 first-birth schedule median grandmotherhood came at 44. Under the 2024 schedule it is 57, cutting the healthy years with grandchildren from 28 to 15. Longer life does not make up the loss of years when the grandmother is healthy enough to supply money and care. Delay is most pronounced among the college-educated, with reproductive-control access accounting for over half the fall in grandmotherhood by age 55 among White college graduates. When a daughter times her first birth to maximize her own payoff, the loss her choice imposes on her mother is external to her calculation. We call this the Rotten Adult Kid Problem. Delay raises both the price of a grandmother's care and wealth per grandchild.

Papersocarxiv9/21/2026

Research on Gender Contradictions in Contemporary China: Structural Pressures, the Negativity of Marital Surplus, and the Gender Projection of Class Contradictions

AI summaryThis paper challenges individual-preference and gender-norm explanations for declining marriage and birth rates and rising gender tensions in China, instead proposing a structural economic model—the "Dual Marriage Costs–Expectation Mismatch Integrated Model" (Di Formula)—that accounts for rising direct marriage costs for men (housing, weddings, bride price, childbearing, education) and rising opportunity costs for women (from higher education, job market constraints, and the motherhood penalty). It introduces the concept of "marital surplus," arguing that when this net benefit of marriage relative to singlehood turns negative due to widening mismatches between modern expectations and resource constraints, individually rational decisions to delay or forgo marriage aggregate into lower marriage/birth rates and heightened gender conflict, reframing marriage as an increasingly high-cost, high-risk economic decision rather than a cooperative family mechanism.

Abstract

Against the backdrop of a sustained decline in marriage and birth rates in China and intensifying gender tensions, traditional explanations centered on individual preferences or gender norms are insufficient to account for the structural mechanisms involved. Drawing on the economics of marriage and the family, this paper examines how rising costs of housing, weddings, bride price, childbearing, and education affect men's decisions to enter marriage, as well as how the expansion of higher education, the shortage of standardized professional employment, and the motherhood penalty shape women's opportunity costs associated with marriage. Building on these factors, together with declining expectations of economic growth, changing lifestyle expectations, and the rising utility of singlehood as an alternative, the paper proposes the “Dual Marriage Costs–Expectation Mismatch Integrated Model” (the Di Formula) and uses “marital surplus” to characterize the comprehensive net benefits of marriage relative to singlehood. The paper argues that contemporary gender relations in China involve more than a conflict of values, but separately rising direct marriage costs for men and opportunity costs for women, together with a widening structural mismatch between modernity-based expectations and real resource constraints. When marital surplus declines and eventually becomes negative, individually rational decisions to postpone or forgo marriage may, in aggregate, contribute to declining marriage and birth rates and intensified gender tensions. Marriage is therefore increasingly shifting from a traditional mechanism of family cooperation toward a high-cost, high-risk, long-term economic decision.

Papercrossref-catchall9/18/2026

Fertility Decline, Urbanization, and Stationary Long-Run Population Levels

AI summaryThis paper develops a model of endogenous fertility and urban migration in which incomes rise with population density due to agglomeration effects, and children are costly in both goods and space. A stronger agglomeration effect triggers rising urban migration alongside falling fertility in both urban and rural areas—driven by higher rents in cities and falling incomes in rural areas—patterns resembling U.S. data. In the long run, the rural population disappears while the urban population rebounds to its original density.

Abstract

This paper sets up a model with endogenous fertility and urban migration. Children are costly in terms of both goods and space. Incomes depend on population density through an agglomeration effect. An increase in the strength of the agglomeration effect can set in motion a process whereby urban migration increases, and fertility rates fall in both urban and rural locations, similar to U.S. data. Urban fertility falls due to rising rents while rural fertility falls because incomes fall. The rural population vanishes in the long run but the urban location rebounds, ending up with the same population density that it started off with.

Papersocarxiv9/17/2026

The Dual Costs of Marriage and Expectation Mismatch: A Mechanism for Understanding Gender Conflict in Contemporary China

AI summaryThis paper develops a

Abstract

Against the backdrop of a sustained decline in marriage and birth rates in China and intensifying gender tensions, traditional explanations centered on individual preferences or gender norms are insufficient to account for the structural mechanisms involved. Drawing on the economics of marriage and the family, this paper examines how rising costs of housing, weddings, bride price, childbearing, and education affect men's decisions to enter marriage, as well as how the expansion of higher education, the shortage of standardized professional employment, and the motherhood penalty shape women's opportunity costs associated with marriage. Building on these factors, together with declining expectations of economic growth, changing lifestyle expectations, and the rising utility of singlehood as an alternative, the paper proposes the “Dual Marriage Costs–Expectation Mismatch Integrated Model” (the Di Formula) and uses “marital surplus” to characterize the comprehensive net benefits of marriage relative to singlehood. The paper argues that contemporary gender relations in China involve more than a conflict of values, but separately rising direct marriage costs for men and opportunity costs for women, together with a widening structural mismatch between modernity-based expectations and real resource constraints. When marital surplus declines and eventually becomes negative, individually rational decisions to postpone or forgo marriage may, in aggregate, contribute to declining marriage and birth rates and intensified gender tensions. Marriage is therefore increasingly shifting from a traditional mechanism of family cooperation toward a high-cost, high-risk, long-term economic decision.

Papersocarxiv9/17/2026

The Latin American Demographic Boom in Spain. Mass Immigration and Ethnic Convergence in a New Country of Immigration

AI summaryThis study examines Spain's rapid shift from an emigration to immigration country between 2000 and 2022, using register data, birth analysis by parental background, and cohort-component modeling to track population diversity, finding that the foreign-background population under 40 rose from 5% to 28%, with 13% of Latin American origin by 2022. Projections to 2062 suggest this share could exceed 65% (32% Latin American) if current migration, fertility, and mixing patterns persist, highlighting how immigration reshapes native-born populations through births and ethnic mixing across generations, not just through foreign-born growth.

Abstract

Since the late twentieth century, Spain has undergone a rapid transition from emigration to immigration country, receiving around 510,000 immigrants annually between 2000 and 2022, approximately half from Latin America. This transformation has substantially increased population diversity, yet less is known about how diversity develops in relatively new immigration countries compared with established destinations. We combine register data, a retrospective analysis of births by parental background and a multi-state cohort-component model to examine changes in population diversity between 2000 and 2022 and project its potential evolution to 2062. The results show a rapid transformation of Spain’s population composition. Between 2000 and 2022, the share of the population under 40 with a foreign background – defined by country of birth and parental origins – increased from 5% to 28%, while 13% had a Latin American background in 2022. Assuming that migration, fertility and ethnic-mixing patterns remain constant, the share of the population under 40 with a foreign background would exceed 65% by 2062, with those of Latin American background reaching 32%. These findings demonstrate that the demographic consequences of immigration extend beyond the growth of the foreign-born population, as births and ethnic mixing progressively reshape the Spanish-born population. The study highlights the importance of incorporating foreign family backgrounds when assessing population diversity and provides new evidence on how diversity may evolve across generations in a recent immigration country.

Papersocarxiv9/16/2026

Global Trends in Widowhood Prevalence, 1970–2020: The Role of Population Ageing, Mortality, and Union Dynamics

AI summaryThis study examines global widowhood trends from 1970–2020 using marital-status data from 222 countries and territories, finding that widowhood prevalence declined overall and especially among women, despite population ageing. A Kitagawa decomposition of changes between 1980 and 2010 across 135 populations revealed that while ageing pushed widowhood upward, declines in age-specific prevalence (driven by mortality and union dynamics) more than offset this effect, suggesting an ageing world does not necessarily mean more widowhood, though large vulnerable populations still experience spousal loss.

Abstract

Widowhood is the predominant marital status at older ages, especially among women. Although population ageing is expected to increase widowhood, evidence on this trend remains scarce or fragmented across countries. This study contributes to the global understanding of widowhood by addressing two questions. First, how has widowhood prevalence changed among women and men across countries and world regions between 1970 and 2020? Second, to what extent are changes in overall widowhood prevalence attributable to changes in population age structure rather than to changes in age-specific widowhood prevalence, i.e. mortality and union dynamics. We gathered marital-status tabulations from censuses, registers, and nationally representative surveys covering 222 countries and territories, and trace crude and age-standardized widowhood prevalence from 1970 to 2020. A Kitagawa decomposition separates change between 1980 and 2010 in 135 populations into age-structure and age-specific-prevalence components. Widowhood prevalence declined globally and in most regions, especially among women. Although population ageing contributed to increasing widowhood prevalence, changes in age-specific prevalence more than offset this effect. An ageing world is not necessarily one in which an increasing share of people are widowed, but it may still be one in which large, socially vulnerable populations live with the consequences of spousal loss.

Papercrossref-pdr9/16/2026

How Political Events Become Demographic: Toward a Cumulative Demography of Conflict and Violence

AI summaryThis piece addresses the mixed findings linking political conflict and violence to demographic outcomes such as mortality, migration, fertility, union formation, health, and kinship. It proposes three priorities for building a cumulative conflict demography: distinguishing exposure from actual impact and meaning-making, identifying generalizable social mechanisms that can yield context-dependent results, and developing macro-level analyses of population size, composition, and distribution that go beyond micro-level mechanisms. The articles in the issue are presented as exemplifying these priorities toward a methodologically plural research program.”

Abstract

Abstract Political conflict and violence shape the core demographic processes of mortality, migration, and fertility, while also influencing union formation, health, and kinship networks. Existing studies have often asked whether conflict is positively or negatively associated with demographic outcomes, yet findings remain strikingly mixed. This reflects the heterogeneous nature of conflict and violence themselves, the institutional and social contexts in which they occur, and the multiple, interacting processes through which they influence demographic outcomes. To advance a cumulative research program for conflict demography, we identify three priorities. First, researchers should distinguish exposure to conflict and violence from the extent to which individuals are affected by them and take seriously the processes of meaning‐making through which conflict events acquire demographic significance. Second, researchers should identify a limited set of generalizable social mechanisms that connect conflict and violence to demographic outcomes, recognizing that the same mechanism can produce different empirical results in different contexts. Third, researchers should develop macro‐level analyses of conflict‐affected populations because changes in population size, composition, and distribution are population‐level processes that cannot be derived solely from micro‐level mechanisms. The articles in this issue exemplify these three priorities and together outline a methodologically plural program for a cumulative conflict demography.

Papercrossref-catchall9/15/2026

The Fertility Dividend: Family Size and the Decline in Child Poverty

AI summaryThis study finds that 5.4 percentage points—27%—of the 20-point decline in U.S. child poverty (under the Supplemental Poverty Measure) between 1967 and 2024 stems from a 'fertility dividend,' as smaller families spread finite resources across fewer children, translating to about 3.7 million fewer children in poverty in 2024. The author argues that conventional decompositions misattribute this demographic shift to income growth because equivalence scales condition on family size, and corroborates the mechanism using twin-induced parity transitions, which raise child poverty by 3-7 points.

Abstract

Child poverty under the Supplemental Poverty Measure fell 20 percentage points between 1967 and 2024, a decline conventionally credited to income growth and changing taxes and transfers. I show that 5.4 points—27% of the decline or 3.7 million fewer children in poverty in 2024—instead reflect a fertility dividend: smaller families spread finite resources across fewer children. Because equivalence scales and decompositions condition on family size, standard accounting records demographic change as income growth. I quantify the dividend with a rank-preserving transport of the family-size distribution, and corroborate the mechanism by showing that twin-induced parity transitions still raise child poverty 3–7 points.

Papercrossref-catchall9/15/2026

The Silent Constraint: Human Development, Fertility Transition, and India's Demographic (Gender) Dividend

AI summaryThis paper examines India's rapid, below-replacement fertility transition, noting it diverges from the international pattern where fertility decline typically accompanies broad gains in education, health, women's agency, and economic transformation. Instead, India's compressed fertility decline was driven largely by state-led family-planning interventions, particularly female sterilisation, rather than parallel human development progress. This weakens the conventional link between fertility decline and socioeconomic transformation, raising questions about India's prospects for realizing a demographic (gender) dividend.

Abstract

India's attainment of below-replacement fertility marks a major demographic milestone, yet it presents a paradox when viewed against international experience. In most countries that successfully harnessed a demographic dividend-particularly in East Asia and parts of Europe-fertility decline emerged alongside broad improvements in education, health, women's agency, labour-market opportunities, and structural economic transformation. In contrast, India's fertility transition was unusually rapid, compressed into a few decades, and was driven to a significant extent by state-led family-planning interventions, especially female sterilisation, rather than by comparable advances in human development. This divergence weakened the conventional linkage between fertility decline and socioeconomic transformation.

Preprintcrossref-catchall9/15/2026

A New Interpretation of the Demographic Transition

AI summaryThis 2006 conference paper reinterprets the demographic transition as a consequence of natural selection optimizing "verifiable fitness"—offspring surviving to reproductive maturity—rather than as a purely sociological phenomenon. It argues falling child mortality raises the effective cost of births, ties old-age provision to the same resource budget as children, and frames the mortality-fertility decline gap as an information-diffusion lag linked to linguistic fragmentation and urbanisation, explaining Princeton European Fertility Project findings while predicting convergence toward roughly one child per couple rather than replacement fertility. The paper derives a fertility function, offers six testable hypotheses, and is accompanied by a 2026 monograph evaluating its predictions against subsequent data.

Abstract

<p>This paper, written in 2006 was presented at the Conference "Causal Analysis in Population Studies", Vienna, 30 Nov. - 1 Dec. 2006. It is posted here unaltered, and proposes that the demographic transition is a direct consequence of natural selection rather than a sociological regularity in search of a cause. It argues that selection optimises not the number of births but the number of offspring whose arrival at reproductive maturity the progenitor survives to witness — a quantity the paper terms <i>verifiable fitness</i>.</p> <p>Three consequences follow. Falling child mortality raises rather than lowers the effective price of a birth, because a larger fraction of births now require full investment. Old-age provision and healthcare are purchased from the same budget as children and are deducted first, so societies that succeed at self-survival buy that success partly with gene survival. And the interval between mortality decline and fertility decline is an information-diffusion lag, proportional to linguistic fragmentation and inversely proportional to urbanisation, which predicts that transitions occur in cultural rather than economic units — the central and otherwise awkward finding of the Princeton European Fertility Project.</p> <p>The paper derives a fertility function, calibrates it across three development levels, and states six testable hypotheses. It predicts convergence toward approximately one child per progenitor dyad rather than toward replacement, on the ground that individually optimal fitness strategies need not preserve the group.</p> <p></p> <p>The paper is posted for priority. A companion monograph, <i>The Price of Verification</i> (2026), scores its predictions against the 2006–2026 record, documents where it was wrong, and extends it.</p>

Data releaseunpd9/14/2026

National Transfer Accounts (NTA)

AI summaryNational Transfer Accounts (NTA) is a comprehensive framework that measures production, consumption, asset income, and transfers across different age groups. It helps clarify how population growth and changing age structure influence economic growth, public finances, and generational equity.

Abstract

Language Undefined A comprehensive framework that measures how production, consumption, asset income, and transfers by age groups. NTA clarifies how population growth and changing age structure affect economic growth, public finances, and generational equity. Feature content:&nbsp; No

Papernber9/14/2026

Immigration and Child Mortality during the Age of Mass Migration -- by Katherine Eriksson, Peter Zhixian Lin, Gregory Niemesh

AI summaryThis study uses newly constructed town-level panel data from Massachusetts (1860–1915) and a shift-share instrumental variable approach to examine how immigration affected local mortality during the Age of Mass Migration. The authors find that increases in the foreign-born share significantly raised infant and child mortality, particularly in the post-neonatal period, with effects extending to native-born children rather than being driven mainly by higher mortality among immigrant births themselves. The findings suggest immigration influenced local disease environments and contributed to shaping the broader mortality transition in crowded, high-mortality settings.

Abstract

In the late nineteenth century, Americans feared that crowded immigrant neighborhoods were spreading disease through industrial cities. We study this claim using newly constructed town-level panel data from Massachusetts, 1860 to 1915, a setting uniquely suited to this exercise because its early vital registration system allows consistent measurement of mortality before national registration became widespread. Using a shift-share instrumental variable strategy based on historical settlement patterns, we estimate the effect of local exposure to immigration on mortality. The relevant question is not whether immigrant families themselves experienced higher mortality, but whether immigration altered the local disease environment more broadly. We find that increases in the foreign-born share significantly raised infant and child mortality, with the infant effect falling disproportionately on the post-neonatal period. Mechanical changes in the composition of births by parent nativity account for only a portion of the estimated effect, implying that the results are not driven primarily by higher mortality among immigrant births. Instead, the evidence is consistent with increased exposure to immigrants, communicable disease, and spillovers to children of native-born parents. These findings highlight immigration as one factor shaping the mortality transition in crowded high-mortality environments.

Papercrossref-population-studies9/11/2026

Temperature shocks and childbearing in Australia

Papercrossref-pdr9/11/2026

Fertility Dynamics across High‐Income Countries in a New Era of Polycrisis

AI summaryThis study examines fertility trends in 26 high-income countries during the COVID-19 pandemic and subsequent polycrisis, including the Ukraine war. It finds that early pandemic fertility declines were short-lived and mostly rebounded, but a second phase saw strongly negative excess fertility rates in Eastern/Central Europe and several Western European countries, linked to rising consumer prices and falling consumer confidence. The findings suggest economic conditions and public confidence are key drivers of fertility under compounding uncertainty, with strong welfare states not guaranteeing fertility resilience and substantial variation across countries.

Abstract

Abstract The COVID‐19 pandemic opened a polycrisis of interrelated disruptions and compounding economic and subjective uncertainty that likely shaped fertility in high‐income countries, especially in its second phase, in which the Ukraine war was a major source and amplifier of uncertainty. Yet fertility evidence remains largely limited to the pandemic. We estimate monthly “excess” total fertility rates (TFRs) and find that declines compared to projected pre‐polycrisis trends were short‐lived during the first phase and excess TFRs overall positive in all 26 sample countries except Eastern Europe and Portugal. Instead, during the second phase, excess TFRs are strongly and increasingly negative in Eastern and Central Europe, Greece, Portugal, France, Denmark, and Sweden. Investigating potential explanatory variables, we find that the total, energy, and housing consumer price indices and reversed consumer confidence are negatively associated with excess TFRs, especially in Eastern and Central Europe, Greece, France, Denmark, and Sweden. Refugee inflows, the economic policy uncertainty index, and the geopolitical risk index show weaker negative associations. But country heterogeneity is large. Our analysis suggests that fertility dynamics are closely linked to the polycrisis, citizens’ economic conditions and confidence are the strongest correlates, and extensive welfare regimes alone may not consistently sustain fertility under accumulating uncertainty.

REG_EUROPEfertility.tfr
Papersocarxiv9/9/2026

Towards a demographic analysis of kinship bereavement

AI summaryThis study develops a demographic framework with three indicators—bereavement burden, shared time lost, and generational overlap—to compare kinship bereavement across populations, applying it to 1950 female cohorts in Argentina and Guatemala using UN-2024 data and matrix kinship models. Results show Guatemala experiences higher burdens and more overlapping death schedules for child and sibling deaths, while Argentina shows higher grandparent burden, greater shared time lost per child death, and more sequential loss patterns across generations. The authors conclude that similar death counts can mask very different bereavement experiences, and their framework extends formal kinship demography by enabling systematic cross-regime comparisons using standard population data.

Abstract

BACKGROUND Kin deaths are universal, but their frequency, timing, and position within family networks vary across demographic regimes. Existing demographic research describes kin loss, but provides limited tools for summarizing its cumulative and life-course consequences. OBJECTIVE We develop a demographic framework to compare bereavement regimes across populations, focusing on three dimensions: cumulative burden, loss of shared lifetime, and generational overlap in kin deaths. METHODS We derive three indicators from age-specific kinship dynamics: bereavement burden, defined from kin-years lived after kin death; shared time lost, measured as expected kin-years of potential coexistence removed by death; and generational overlap, measuring coincidence between age-specific death schedules of different kin types. We apply the framework to female 1950 cohorts in Argentina and Guatemala using UN-2024 data and matrix kinship models. RESULTS The comparison identifies contrasting bereavement regimes. Guatemala has much higher burdens from child and sibling deaths and larger total losses of shared time with these kin. Argentina has a higher grandparent burden and greater shared time lost per child death. Death schedules are also more strongly overlapped in Guatemala, particularly for siblings and parents and for children and parents, whereas Argentina displays a more sequential ordering of losses across generations. CONCLUSIONS Similar death counts can conceal markedly different bereavement experiences. The demographic meaning of loss depends on when deaths occur, how many kin are exposed, and how losses are sequenced across generations. CONTRIBUTION We extend formal kinship demography by providing three interpretable indicators that allow bereavement to be compared systematically across demographic regimes using standard population data.

Policyunpd9/8/2026

Workshop: Measuring the Generational Economy: National Inclusion Accounts for Inclusive Policymaking

AI summaryThis is a program announcement for a UN-organized workshop (co-hosted by UNDESA, ECLAC, and ESCAP) on Measuring the Generational Economy, presenting National Inclusion Accounts as a new extension of the National Transfer Accounts framework. The event showcases results from a Development Account pilot project in eight countries across Latin America/Caribbean (Colombia, Costa Rica, Jamaica, Uruguay) and Asia/Pacific (Lao PDR, Malaysia, Maldives, Viet Nam), covering topics like population ageing, inequality, unpaid care work, and intergenerational support to inform inclusive fiscal and social policymaking. The agenda includes country presentations, regional policy panels with perspectives from Africa, Asia, Europe, and Latin America, and discussions on applying these accounting frameworks for long-term policy design.

Abstract

Monday, 26 October 2026 - 9:00am Overview The meeting on Measuring the Generational Economy: National Inclusion Accounts for Inclusive Policymaking is co-organized by the United Nations Department of Economic and Social Affairs, the Economic Commission for Latin America and the Caribbean, and the Economic and Social Commission for Asia and the Pacific. It builds on a Development Account project supporting the implementation of National Inclusion Accounts in eight pilot countries across two regions: Colombia, Costa Rica, Jamaica and Uruguay in Latin America and the Caribbean; and Lao PDR, Malaysia, Maldives and Viet Nam in Asia and the Pacific. These countries represent diverse stages of the demographic transition and varying levels of economic development, offering a rich basis for comparative learning and policy dialogue. Through their work, the pilot countries demonstrate the potential of National Inclusion Accounts to generate policy-relevant evidence on inequality, intergenerational support and the distribution of resources across population groups. The meeting will provide a platform to present country results, exchange experiences, and discuss how National Transfer Accounts and its extensions can be used to support fiscal planning, social protection, inclusive growth and long-term policymaking. The objective of the meeting is to introduce National Inclusion Accounts as a new extension of the National Transfer Accounts (NTA) framework and to showcase results from eight pilot countries supported under the Development Account project, a collaboration of DESA, ECLAC and ESCAP. The meeting will provide a strategic overview of NTA and its related extensions — National Time Transfer Accounts and National Inclusion Accounts — as decision-support tools for fiscal planning, social protection, inclusive growth and long-term policymaking. It will highlight how these frameworks generate evidence on the respective roles of governments, families and markets in supporting individuals across the life course. The meeting will also provide an opportunity for policymakers and partners to share policy applications of National Transfer Accounts and its extensions, including how these tools can inform responses to population ageing, inequality, unpaid care work, intergenerational support, and the design of more inclusive and sustainable policies. &nbsp; Document Concept note &nbsp; Organization of work Monday, 26 October 2026 &nbsp; &nbsp; Morning session — Chair: DESA (Cheryl Sawyer, Chief, Population Trends And Analysis Branch, UNDESA Population Division) &nbsp; 9.00 – 9.20 a.m. Welcome Remarks United Nations: Lin Yang, Deputy Executive Secretary, ESCAP&nbsp; &nbsp; China National Committee on Ageing: Madam Lv Xiaoli, Vice Commissioner, CNCA&nbsp; HelpAge International: Eduardo Klein, Regional Director, HelpAge&nbsp; &nbsp; 9.20 – 10.15 a.m. Population Ageing: Global, Regional and Country Responses Nicole Mun Sim Lai, Population Affairs Officer, UNDESA Population Division.&nbsp; Global population ageing: the role of DESA &nbsp;&nbsp; &nbsp; Sabine Henning, Chief, Sustainable Demographic Transition Section, ESCAP.&nbsp; Population ageing in Asia and the Pacific: the role of ESCAP ECLAC.&nbsp; Population ageing in Latin America and the Caribbean: the role of ECLAC China National Committee on Ageing.&nbsp; Responding to population ageing in China: policies, progress and future outlook Q & A &nbsp; 10:15 – 10:25 a.m. Group Photo &nbsp; 10:25 – 10:45 a.m Coffee Break &nbsp; 10:45 a.m. – 12:00 p.m. National Inclusion Accounts in Latin America and the Caribbean Moderator: Raul Holz, Senior Researcher, ECLAC Colombia&nbsp; &nbsp; &nbsp; &nbsp; Costa Rica&nbsp; &nbsp; &nbsp; Jamaica&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Uruguay&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Q & A&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; 12:00 – 13:30 p.m.&nbsp; &nbsp; &nbsp; Lunch Break &nbsp; &nbsp; Afternoon session: Chair: ESCAP &nbsp; 13:30 – 15:15 p.m. Policy Panel Discussion: Population Ageing — NTA, NTTA and NTA-I Moderator: Nicole Mun Sim Lai, Population Affairs Officer, UNDESA Africa perspective: Senior country representatives from Africa&nbsp;&nbsp; &nbsp; Asia perspective: Eduardo Klein, Regional Director, HelpAge; Professor Sang-Hyop Lee, University of Hawaii at Manoa Europe perspective: Agnieszka Chłoń-Domińczak, President, Government Population Council (GPC), Poland&nbsp;&nbsp; &nbsp; Latin America and the Caribbean perspective: Two senior representatives from Latin America and the Caribbean&nbsp;&nbsp; &nbsp; Q & A (Discussant: Professor Long, Viet Nam)&nbsp; &nbsp; 15:15 – 15:35&nbsp; p.m. Coffee Break &nbsp; 15:35 – 16:50 p.m. National Inclusion Accounts in Asia and the Pacific Moderators: Marco Roncarati, Social Affairs Officer, ESCAP; Napaphat Satchanawakul, Social Affairs Officer, ESCAP China: Professor Shen Ke, Fudan University Lao PDR Maldives Viet Nam Q & A&nbsp; &nbsp; 16:50 – 17:00 p.m.&nbsp;&nbsp; Closing Remarks & Next Steps Cheryl Sawyer, UNDESA &nbsp; &nbsp;