Enslaved, enserfed, and otherwise dependent peoples always existed within larger populations, living alongside people with other statuses. Sometimes, the enslaved were the immediate kin of their owners. In other cases, such as eunuchs, they were biologically quarantined. In every population, the enslaved were at least potentially exposed to the same conditions of life as their masters. Just as the social relation of enslavement or dependency did not stem from a natural separation of people, so it is necessary to consider the enslaved as part of the larger population in which they were embedded, capable of contributing to its growth and decline. Slave and free were connected, however unwillingly and unwittingly, by kinship, epidemiology, environment, and governance. It was the character of these connections that determined patterns of shared demographic experience and patterns of difference. In some cases, the difference in wealth and welfare between owner and slave was relatively narrow; in others, the gap was huge, with owner and slave living in different continents, invisible to one another. The consequences of these variations for demographic performance were substantial for both slave and free.

MODELS AND THEORIES

Ideas about the demographic significance of enslavement and other forms of dependency were most often expressed by free people, many of them leisured intellectuals and some of them directly enriched by slaveowning. When proslavery thought came gradually to confront emergent streams of antislavery argument in the eighteenth century, both sides gave substantial weight to demographic factors in the debate over the economics and moral justice of slavery as a system.