Demographics

The demography of the Roman Empire is a much debated subject. A lack of sources prevents any “hard” conclusions. The many funerary inscriptions, for example, do not lend themselves to any reconstruction of the age structure of the population, because the ages mentioned on the stones are not always accurate and the inscriptions are not representative of the population at large. We have to make do, therefore, for the overall population of the empire, with comparisons with other pre-modern societies. Much uncertainty notwithstanding, we may assume that the picture of a pyramid with a very broad base and only a narrow peak reaching the higher ages—the result of high infant and child mortality—was valid for the empire just as it had been for earlier periods in antiquity. Likewise, the question of the total number of inhabitants of the empire and its fluctuations can only be answered by more or less informed guesses. For cities and provinces, estimates can be made, but the sum total of all estimates has necessarily a high measure of uncertainty. Thus, the calculations or estimates of the number of inhabitants of the Roman Empire in the 1st century AD vary from 50 to 80 million, and those of the city of Rome from 400,000 to well over 1 million. Rome was no doubt a unique metropolis; other large cities such as Alexandria, Antioch, and Carthage in all probability did not surpass the 300,000 mark, or even the 200,000 mark. A very few cities might have had about 100,000 inhabitants, a handful others between 25,000 and 100,000, but the vast majority of the more than 1000 towns and cities of the empire had between 5,000 and 20,000 inhabitants. When it comes to the population of the countryside, our uncertainties only increase. It is more than probable that there must have been fluctuations in the numbers of inhabitants in various regions.

In general, the population of the empire seems to have reached its highest peak in the 2nd century. In the 3rd century, there must have been a decline in population, especially in the western half, but certainly not everywhere, while toward the end of the century and in the following 4th and 5th centuries the population in the eastern half must have recovered and even increased, while in the west the population levels of the 2nd century would not be reached again for many centuries.

The factors that could explain long-term changes in the size of the population are not always clear. Wars and epidemics generally seem not always to have played a decisive role, since the population losses caused by these calamities tended to be made up for within a few generations. That said, the catastrophes that struck the empire in the 2nd and 3rd centuries AD —a severe epidemic after 166 AD that probably introduced smallpox into the Roman world, another epidemic around the middle of the 3rd century, perhaps measles, not to mention near-constant wars and foreign invasions—were of such a nature that they must have led to a population decline that in most of the western half of the empire was simply too serious to allow for a speedy recovery. In the eastern half, however, as stated, the population seems not only to have recovered in the later 3rd and 4th centuries but to even have increased somewhat. A more important factor than mortality for population increase or decrease is, in general, the prevailing fertility rate. Changes brought about in the rate of fertility by changes in diet, health, society, mentality or religion, inevitably have their effects in the form of an increase or decrease of population. The Christianization of the Roman Empire and the accompanying diffusion of certain ascetic ideals might therefore, as was already suggested, have had some negative consequences for the overall size of the population. However, not only must this remain a presupposition, it is also a fact that asceticism was in the 4th and 5th centuries AD stronger in the east than in the west of the empire, which suggests that this factor can at most have played a secondary role. So we must conclude that epidemics and social and political upheavals were more important (in the 6th century the east would be ravaged by invasions and an epidemic and then in its turn suffer a population decline).