About me
Hi! I’m a postdoctoral researcher in demography at Magdalen College, Oxford and the Assistant Director of the Calleva Research Centre, Magdalen’s interdisciplinary centre of research excellence. In Summer 2026, I submitted my PhD thesis at the London School of Economics, and I am currently awaiting my viva.
I teach demography on the BA Human Sciences and BA Philosophy, Politics, and Economics courses in Oxford, running quantitative classes and essay-based tutorials.
I am an affiliate of the Leverhulme Centre for Demographic Science at the University of Oxford, and throughout 2024, I was a Research Fellow (Forsker III) at Oslo Metropolitan University’s Centre for Research on Pandemics & Society (PANSOC). My work has been the recipient of an IPUMS Research Award and the European Society of Historical Demography’s Roger Schofield Award for Best Paper by a Young Demographer.
Most of my work focuses on the societal impacts of social and demographic crises. I have a particular focus on better understanding the 1918 influenza pandemic, but I have also worked on the trends in high-income national fertility after the 2009 global financial crisis and on the geography of mental health around the 2016 Brexit referendum in the UK. One of my bigger collaborative projects uses census microdata data from 1880s through the 2010s to test how polygyny affects marriage markets and might impact social conflict.
Beyond Oxford, I am involved in the wider community of demographers, serving on the management board of the Association for Young Historical Demographers and the EU-funded GreatLeap project.
Prior to my PhD, I completed a MPhil in Demography at Nuffield College, Oxford and Oxford’s Department of Sociology. Before that, I completed a BA in Human Sciences at the University of Oxford, an interdisciplinary programme of biology and social science.
Latest publications
- Gaddy, H. (2026). We are our memory: A flexible framework for quantifying the demographic imprints of the past. Population and Development Review, 52(2): 265–298. doi:10.1111/padr.70074
- Gaddy, H., Sear, R., & Fortunato, L. (2025). High rates of polygyny do not lock large proportions of men out of the marriage market. PNAS, 122(40): e2508091122. doi:10.1073/pnas.2508091122
Current projects
If you want to read what I am working on at the moment, here are preprints of a few of my current projects!
- “The missing Pacific influenza epidemics, 1918–21” (with Svenn-Erik Mamelund and Michael G Baker), doi:10.31235/osf.io/4mb5a_v2
- “Death registration incompleteness and demographic structure obscure the inequality of Alaska Natives in the 1918 influenza pandemic”, doi:10.31235/osf.io/yu7bt_v1