Complex systems reveal health risks of 19th-century South Australian migrants

Angela Gurr and colleagues set out to understand why a small, rare archaeological sample of early migrants to South Australia showed signs of poor health and death in the 19th century. Rather than treating bones and documents separately, the research used a Complexity perspective called Complex Adaptive Systems (CAS) to bring different kinds of evidence together. The skeletal collection came from a group buried in an unmarked area of St Mary’s Anglican Church Cemetery, and the team paired the physical remains with historical sources: records of British emigrant ships to SA (1836 to 1885) and the Church burial records (1847-1885). By combining bioarchaeological data with historical documents, the researchers aimed to get a fuller, more nuanced picture of migrant health — not just which diseases were present, but how travel conditions, life in the Colony, and wider social and economic forces may have interacted to shape who got sick and why. Naming Angela Gurr as corresponding author, the study argues that a CAS framework can capture complex interactions that single-source studies often miss, opening a new way to read lives from the past.

To study the remains the team applied Macroscopic, radiographic and micro-CT methods to examine bones and teeth in detail. The physical evidence showed poor oral and general health: dental developmental defects suggested that individuals experienced health insults early in life. Pathological changes in bone were compatible with joint disease, infectious disease, and metabolic deficiencies. These bioarchaeological signals were read alongside documentary evidence from British emigrant ships to SA (1836 to 1885) and Church burial records (1847-1885). The historical records described difficult voyages, with some ships experiencing high death rates, and listed diseases such as measles and scarlet fever, and diarrhoea as frequent causes of death at sea for both subadults and adults. Once in the Colony, burial records recorded similar causes of death for subadults, while adults were more often listed as dying from accidents and tuberculosis. Together, the physical and documentary records painted overlapping but not identical pictures of illness and mortality.

Using a Complex Adaptive Systems (CAS) lens helped the team see more than the sum of bones plus records. The CAS approach emphasized that health outcomes emerged from interactions among many factors, including the conditions of the voyage, life in the new Colony, and wider forces that changed over time. The study highlights how non-predicted, emergent outcomes can result when fluctuating economy, political instability and ideological pressures interact with individual vulnerability and disease exposure. This means that explanations that focus on a single cause — a specific infection or a single journey hazard — can miss important parts of the story. The researchers argue that the CAS framework is a valuable methodology for interpreting health patterns and can be developed further for a range of historical and contemporary health contexts, offering a more holistic tool for historians, archaeologists and public health researchers interested in how complex causes produce real human suffering.