A joint project of the UT-Austin Population Research Center and Economics Department.

The Population Wellbeing Initiative at UT-Austin is a network of researchers who conduct foundational research in economics, demography, and social welfare evaluation. We are a global priorities research center that specializes in quantitative social science research. Issue and project areas include: fertility, parenting, and the future of population and economic growth; infant and child welfare; animal welfare, and policy evaluation from a long-term perspective.

People

Directors

News

Dean Spears gives DeJong Lecture at Penn State on his new book with Mike Geruso, After the Spike: Population, Progress and the Case for People (available for pre-order).

Wall Street Journal collaboration with Dean Spears’ analysis. (7/24)

80,000 Hours podcast interview with Dean Spears on cost-effective methods for reducing neo-natal mortality. (5/24)

New York Times piece on the future of population published by Dean Spears. (9/23)

New NIH grant awarded. 08/23 – 08/24. University of Texas-Austin Center on Aging and Population Sciences (P30AG066614, National Institute on Aging), “The Age Process of Fertility and Fecundity: New Facts and Implications for Population Dynamics.”

Events and Visitors

Lea Bart (job talk) The Effects of the Family and Medical Leave Act on Women’s Careers (1/22/25)

Anastasia Berg What are Children For? (12/4/24)

Melinda Roberts The Existence Puzzles (11/20/24)

Selected Research

Long-term population projections: Scenarios of low or rebounding fertility. 2024. Dean Spears, Sangita Vyas, Gage Weston, and Michael Geruso. PLOS One. Accompanying New York Times piece (by Dean Spears).

Abstract

The size of the human population is projected to peak in the 21st century. But quantitative projections past 2100 are rare, and none quantify the possibility of a rebound from low fertility to replacement-level fertility. Moreover, the most recent long-term deterministic projections were published a decade ago; since then there has been further global fertility decline. Here we provide updated long-term cohort-component population projections and extend the set of scenarios in the literature to include scenarios in which future fertility (a) stays below replacement or (b) recovers and increases. We also characterize old-age dependency ratios. We show that any stable, long-run size of the world population would persistently depend on when an increase towards replacement fertility begins. Without such an increase, the 400-year span when more than 2 billion people were alive would be a brief spike in history. Indeed, four-fifths of all births—past, present, and future—would have already happened.

What Should We Agree on About the Repugnant Conclusion? 2021. (Many authored statement, lead by PWI). Utilitas. [Media Coverage: The Economist.]

Abstract

The Repugnant Conclusion served an important purpose in catalyzing and inspiring the pioneering stage of population ethics research. We believe, however, that the Repugnant Conclusion now receives too much focus. Avoiding the Repugnant Conclusion should no longer be the central goal driving population ethics research, despite its importance to the fundamental accomplishments of the existing literature.

Animal welfare: Methods to improve policy and practice. 2023. Mark Budolfson, Bob Fischer, Noah Scovronick. Published in Science.

Abstract

There is growing international consensus that animal welfare is a crucial consideration in policy analysis, affecting domains ranging from food systems to biomedical research. Concern for animal welfare also features in many government regulations, certification programs, and institutional ethics codes across the globe and is central to many philanthropic and values-based investment decisions. However, although there are well-developed quantitative tools for incorporating human welfare into policy analysis, comparable tools for animal welfare are in their earliest stages. Without them, it is impossible to assess the net welfare impacts of a policy on humans and nonhumans alike on a common scale, which is crucial for making informed and transparent trade-offs (1). In practice, then, animal welfare is often ignored. Given that animal welfare matters in many cases, there is an urgent need for best-practice methods for integrating animal welfare into decision analyses.

Intergenerational Transmission Is Not Sufficient for Positive Long-Term Population Growth. 2022. Samuel Arenberg, Kevin Kuruc, Nathan Franz, Sangita Vyas, Nicholas Lawson, Melissa LoPalo, Mark Budolfson, Michael Geruso, and Dean Spears. Demography.

Abstract

All leading long-term global population projections agree on continuing fertility decline, resulting in a rate of population size growth that will continue to decline towards zero and would eventually turn negative. However, a literature inspired by mathematical biology has suggested that because fertility is heritable (i.e., higher-fertility parents tend to have higher-fertility children) and heterogeneous within a population, long-term population growth must eventually be positive. In this research note, we show that heritable fertility is not sufficient for positive long-term population growth, for empirical and theoretical reasons. First, empirically, even higher-fertility sub-populations show declining fertility rates which may eventually be below replacement (and in some populations already are). Second, in a simple Markov model, because heritability is imperfect, the combination of heritability and fertility rates may be quantitatively insufficient: it may be that higher-fertility parents nevertheless produce too few children who retain higher-fertility preferences. These results underscore the importance both of understanding the possible consequences of long-term fertility decline and depopulation and of the causal importance of culture and choice in human populations.

Utilitarian benchmarks for emissions and pledges promote equity, climate and development. 2021. Mark B. Budolfson, David Anthoff, Francis Dennig, Frank Errickson, Kevin Kuruc, Dean Spears, and Navroz K. Dubash. Published in Nature Climate Change.

Abstract

Tools are needed to benchmark carbon emissions and pledges against criteria of equity and fairness. However, standard economic approaches, which use a transparent optimization framework, ignore equity. Models that do include equity benchmarks exist, but often use opaque methodologies. Here we propose a utilitarian benchmark computed in a transparent optimization framework, which, could usefully inform the equity benchmark debate. Implementing the utilitarian benchmark, which we see as ethically minimal and conceptually parsimonious, in two leading climate-economy models allows calculation of the optimal allocation of future emissions. We compare this optimum with historical emissions and initial Nationally Determined Contributions. Compared with cost-minimization, utilitarian optimization features better outcomes for human development, equity, and the climate. Peak temperature is lower under utilitarianism because it reduces the human development cost of global mitigation. Utilitarianism, therefore, is a promising inclusion to a set of benchmarks for future explorations of climate equity.

Population Ethics and the Prospects for Fertility Policy as Climate Mitigation Policy. 2021. Mark B. Budolfson and Dean Spears.

Abstract

What are the prospects for using population policy as tool to reduce carbon emissions? In this paper, we review evidence from population science, in order to inform debates in population ethics that, so far, have largely taken place within the academic philosophy literature. In particular, we ask whether fertility policy is likely to have a large effect on carbon emissions, and therefore on temperature change. Our answer is no. Prospects for a policy of fertility-reduction-as-climatemitigation are limited by population momentum, a demographic factor that limits possible variation in the size of the population, even if fertility rates change very quickly. In particular, a hypothetical policy that instantaneously changed fertility and mortality rates to replacement levels would nevertheless result in a population of over 9 billion people in 2060. We use a leading climate-economy model to project the consequence of such a hypothetical policy for climate change. As a standalone mitigation policy, such a hypothetical change in the size of the future population – much too large to be implementable by any foreseeable government program – would reduce peak temperature change only to 6.4°C, relative to 7.1°C under the most likely population path. Therefore, fertility reduction is unlikely to be an adequate core approach to climate mitigation.

Open Positions

We will be hiring for fall 2025, conditional on successful grant funding. We are recruiting researchers across disciplines with expertise in economics, demography, and social evaluation. We strive to recruit a diverse and inclusive team and offer competitive salaries and benefits to attract outstanding scholars.

Research Scientist


Research Scientists will collaborate actively with our team in the production of independent and coauthored research. Annually renewable while the research is successful and funded, potentially for years to come.

Self-directed Postdoctoral Researcher


Postdocs will conduct 100% self-directed research without teaching obligations, while also participating in program activities. Successful candidates will pair a 1-2 year postdoc with deferring the start of a new assistant professor position.

Predoctoral Fellow


Predoctoral Fellows will support the research and activities of the program and participate in program activities, during a typically two-year period of preparation for a PhD.