Life paths through space and time: Adding the micro-level geographic context to longitudinal historical demographic research

Sammanfattning: Historical demographic research is central to understanding past human behaviours and traits, such as fertility, mortality and migration. An essential part of historical demography is conducting longitudinal analyses at the micro-level, which involves the detailed follow-up of individuals over long time periods throughout their lives. By including the geographic context in such analyses, we can study how the environment has affected human living conditions over long time periods. However, the use of micro-level geographic factors in historical longitudinal analyses is seldom feasible because of the absence of data. Thus, studies have been primarily limited to examining the geographic context on an aggregated level.In five papers, this thesis contributes to historical demographic research by adding and utilising micro-level geographic factors in longitudinal historical analyses. First, we develop and implement methods for creating detailed longitudinal geographic data that are integrated with longitudinal demographic micro-level data. We then perform novel studies of the effect of the environment on demographic outcomes at the micro-level.Papers I-III include micro-level geographic factors with longitudinal historical analyses. Paper I contributes to the standardisation of longitudinal demographic data by geographically extending the Intermediate Data Model (IDS) using standardised exchange formats. Paper II presents methods for geocoding longitudinal demographic databases. The core part of the process is to transform geographic objects as snapshots (digitised from historical maps) into longitudinal object-lifeline time representations (with information about the creation, changes and ends of each object). Individuals are subsequently linked to these geographic objects. We geocoded the Scanian Economic Demographic Database (SEDD) from 1813 to 1914. Approximately 53,000 individuals who lived in five rural parishes in southern Sweden are linked to the property units where they lived. Geographic snapshot data (e.g., roads and buildings) are also created. Paper III improves and evaluates the geocoded database, and wetlands in object-lifelines are added.Paper IV investigates how longitudinal demographic analyses are affected by different geocoding levels and presents methods for quantifying geographic factors. In a novel case study, we use a geocoded database to analyse the effect of population density and proximity to wetlands on the risk of dying for the period 1850-1914. We show that even small differences between the property units and coarser geographic levels and the choice of method for quantifying the geographic factors substantially affected the results of the demographic analyses. Therefore, geocoding to property units is likely needed for fine-scale analyses at distances within a few hundred metres. In addition, proximity to wetlands affected the mortality of women, which may indicate exposure to malaria-transmitting mosquitoes.Paper V focuses on the role of nutrition in historical societies by analysing the effect of soil type on child mortality in the five parishes between 1850 and 1914. Certain soil types seem to have influenced agricultural productivity, which in turn affected the nutrition of farmers’ children and their risk of dying. This study adds new findings about the importance of nutrition and agricultural productivity regarding child mortality in preindustrial Sweden.To conclude, this thesis enables the novel inclusion of geographic micro-level factors into historical longitudinal studies. The results increase our understanding about how the micro-level geographic context affected individual living conditions throughout history. The geocoding of the demographic database has also proved to be a unique and important resource for historical and geographic research and a starting point for additional research that includes the micro-level geographic context.