Urbanization may be viewed as a particular manifestation of social change. As such, it is often defined as a process leading originally distinct social systems to a common destination. As an example, it is supposed to facilitate the universal emergence of a European type of nuclear family. In this perspective, many scholars have been eager to determine the extent to which African patterns of familial behavior lose their traditional specific properties. These researchers have in fact equated the problem of measuring urbanization with the problem of measuring the relative decline and persistence of traditional affiliations. Taking as examples the familial systems of two Ivory Coast peoples, the present paper intends to show some of the limitations of this type of analysis.

This essay is essentially a historical survey of the whole career of civilized societies. It seeks to list major probabilities and possibilities and to identify ascertained fact. It takes stock of the present state of knowledge after a long period, almost a century, of study.

The confluence of rivers normally makes for interesting landscapes. With the right topography there are no marshes and, after the initial discovery, the area soon becomes the scene of considerable economic activity. So it is with the confluence of intellectual disciplines. With the right guidelines, the scene becomes one of fertile intellectual interchange.

Interest in the consequences for economic activity of the development of disease, preventive medicine, and of other public health problems is not exactly new. Professor Sigerist, in many ways the doyen of the subject, summarized our background quite well in 1941. “We are”, he wrote, “often inclined to believe that the economic approach to medical problems is new, that we inaugurated it. This is not the case …. Max von Pettenkofer in Munich, reasoned very much along the same lines as we do today” [18:2]. Thus, I have precedent for citing work done in this very city as the logical place to start my discussion. One could, as indeed Sigerist himself did, argue that von Pettenkofer (upon whose work I shall base this analysis) wrote with the knowledge of earlier writers like Chadwick, Simon, Snow, and Budd. But, I am inclined to accept Sigerist's assessment of von Pettenkofer's importance and use his two public lectures as the springboard from which to launch my discussion.

Professor Perlman's paper deals with most of the points which are important in discussing the relationship between health and economic development. I shall therefore confine myself to suggesting a few changes of emphasis and elaborating on some of the points which he mentions only in passing. I shall discuss first the nature of the questions which should be asked in this field, and then the return of the answers which are likely to be provided as a result of future study.

Economists have, in the past generation, become deeply concerned with the problem of economic growth. Of late years, as traditional economic models have demonstrated inadequacies, economists have become increasingly interested in the social and cultural inputs necessary for growth in economic productivity. Human, value-related factors, particularly education, role definition, and the place of science and technology, have taken a place beside the more traditional categories of the economist and economic historian. But these human factors, important though all admit them to be, are, especially in historical contexts, not usually amenable to quantitative methods of datagathering. It is difficult, on the one hand, to evaluate and sample such elusive factors, and on the other hand to define their precise role in social change.

The costs of poor health conditions are difficult to estimate for the Middle Ages. It is possible to establish in a tentative way a normal distribution by age and sex and to define what additional damage pestilence and plague did. One possible index is the number of able bodied persons (assuming persons of a definite age to be able bodied) compared to children, a dependency index. A second index is of the relative number of persons dying before they completed their life as able bodied persons. A third, not related to age, might be the number of persons too poor to pay certain taxes before and after the plague. Such persons were presumably too poor in part because of age or ill health.

Professor Russell was the first historian to try to apply statistical methods to analysis of the effects of epidemic plague on the composition, not just on the total size, of medieval population. He argues now that general plagues differed from the type of the disease that became epidemic after the crop failures of 1315–1317, in sharply lowering the sex ratio and in greatly increasing the burden of child-rearing.