Tracing the missing pieces of the puzzle: how individual cause-of-death data can break through unresolved debates on historical and contemporary health issues

Recent public health crises, such as the SARS and Zika outbreaks and the COVID-19 pandemic, have reinvigorated research into historical health developments, particularly the factors that have driven dramatic increases in life expectancy over the past two centuries. In this context, the fight against infectious diseases has received particular attention. Until recently, however, historical demographers, family historians, and historians of medicine have primarily relied on all-cause mortality analyses or broad cause-of-death groupings. While these approaches have advanced the field, important gaps remain in our understanding of health transitions, the evolution of health inequalities, and their underlying mechanisms. Digitization of individual-level cause-of-death data and the development of the ICD10h classification system offer a promising way forward. We show how this innovation can transform three longstanding debates in historical demography and family history: (1) excess female mortality among children and adolescents, (2) death clustering among infants and young children, and (3) the healthy migrant effect. These debates persist because the mechanisms behind the observed inequalities remain unclear; identifying specific causes of death– or, for migrants, the sources of survival advantage– provides crucial new insights. Because these historical patterns continue to shape contemporary health inequalities– excess female and child mortality in many low income countries and the persistent global healthy migrant effect addressing these questions is not only historically significant but also directly relevant to current global health challenges.