Isles of the Dead: convict death rates in comparative perspective

In the past migration has often come at a cost. In many early modern cities, for example, the death rate exceeded the birth rate. Growth was thus dependent upon attracting new migrants from surrounding areas. The catch was that the immigrants were more susceptible to urban diseases than those who were locally born and had therefore acquired a degree of immunity. It was as though urban conurbations drew in and consumed people (Sánchez 2003: 205). Their continued expansion was dependent upon their allure as destinations where financial advantages could be secured.

Much the same could be said for colonies, but here the risks for migrants were far greater. Ocean voyages in the age of sail were notoriously dangerous and alien diseases encountered on distant shores regularly wrought havoc on populations of European descent. These dangers were well known if little understood. The knowledge that travel could kill, combined with the cost of an ocean passage, acted as a powerful disincentive. Of course there were attractors too, especially in the shape of valuable commodities and abundant cheap land. While these were sufficient to persuade many to migrate, those who took the risk wished to establish themselves as independent producers or traders and certainly not as wage labourers. Labour shortages were thus a major problem that threatened most colonial enterprises.