North America

The indigenous peoples of North America suffered as catastrophic a population decline as did those in what became Latin America. As already suggested, the North American Indians did not live in the same sort of extensive agricultural societies as existed to the south, nor did the new settlers come from a society like those of the Iberian Peninsula. Settlement patterns therefore tended to differ, with family-owned and -operated farms predominating in most of the region except the southeast.

Endemic diseases such as dysentery and malaria, and epidemic diseases such as measles, smallpox, and yellow fever, were prevalent throughout the colonial period, but their severity seems to have differed substantially from North to South. Life expectancy was lower in Maryland than in New England in the seventeenth century, for example, and crude mortality rates were higher and epidemic diseases more severe in the South than the North throughout the eighteenth and nineteenth centuries.

In the eighteenth century, crude death rates in New England ranged from 6 to 20 per 1,000 population, depending on the location of a given community as well as its age structure (Meindl and Swedlund 1977; Dobson 1987). In French Canada during the eighteenth century, the crude mortality rate varied from 23 to 39 per 1,000, again probably depending on the changing age structure of the population (Henripen 1954).

In the early nineteenth century, crude mortality rates varied widely as well. In northern U.S. cities they tended to be in the range of 18 to 25 per 1,000, increasing as one moved south to 80 or 90 per 1,000 in such cities as Savannah and New Orleans (Dob-son 1987). Though there is some disagreement, evi dence now exists that mortality rates increased in the course of the first half of the nineteenth century (Meindl and Swedlund 1977; Kunitz 1984; Fogel 1986). This coincided with the first great wave of Irish immigration to the United States, and it is likely that the new settlers were poorer than their predecessors, lived in more squalid circumstances, and spread new diseases to the rest of the population while suffering disproportionately from diseases themselves. Nonetheless, in the North at least, mortality rates remained remarkably low.

Though mortality crises seem not to have been frequent in New England during the colonial period, regular epidemics of measles and smallpox did sweep the population. They seem to have diminished by the end of the period as both diseases increasingly afflicted children, a sign that the population was becoming sufficiently large to convert the diseases into endemic diseases (Kunitz 1984). In general, however, the curve of mortality from year to year retained the jagged, saw-toothed shape characteristic of the presence of epidemics (Omran 1975), although these were never of sufficient magnitude or frequency to keep populations from growing.

Mortality began to decline after the Civil War, though whether this occurred in the 1870s or 1880s is still a matter of disagreement (Kunitz 1984). Robert Higgs (1973) has estimated that the crude mortality rate declined from between 23 and 29 per 1,000 in the 1870s to 15 to 17 per 1,000 in the 1910s in urban areas; and from 21 to 23 per 1,000 to 14 to 15 per 1,000 in rural areas over the same period. These rates are roughly comparable to those observed among Catholics in Canada in the 1860s: 20.9 per 1,000 (Kalbach and McVey 1971). Among the most important of the identifiable syndromes and diseases were the pneumonia-diarrhea complex of infancy and childhood and tuberculosis. Both afflicted Amerindians, blacks, and immigrants more than native-born whites, and both declined in the late nineteenth and twentieth centuries.

Yet even at their zenith in the middle decades of the nineteenth century, mortality rates in North America were low compared with the rates in most of Latin America half a century later, with the exceptions noted previously: Uruguay and Argentina, with no indigenous Indian populations and a high proportion of European settlers, and Cuba and Panama, which both benefited and suffered from the presence of the U.S. army (Sánchez-Albornoz 1974).

The significance of the decline in mortality from midcentury onward is enhanced by the fact that these were the very years during which masses of immigrants from poverty-stricken regions of eastern and southern Europe flocked to the United States and Canada. Although, in general, immigrants had higher mortality rates than native-born people, they tended to have lower mortality rates than were observed in their countries of origin (Kunitz 1984).

The very low mortality observed during the colonial period is explicable in terms of the dispersed nature of settlement and the fact, supported by data on heights, that the population tended to be well nourished. With the exception of blacks brought as slaves to work on plantations in the South, there was not a large servile class such as existed in much of Latin America. The increase in mortality that seems to have occurred after the colonial period has been attributed to the influx of a large and impoverished immigrant population living in unsanitary and rapidly growing cities.

What, then, explains the decline in mortality after the Civil War, when an even larger influx of immigrants every bit as poor as those who had preceded them flooded the cities? It seems likely that the sources of the change were the remarkable productivity of the industrializing U.S. economy and the reform movements that resulted in sanitary improvements in many cities, as well as in small towns and villages (Levison, Hastings and Harrison 1981).

There were, of course, differences in the mortality rates of different cities. By the end of the nineteenth century, these were attributable largely to differences in deaths of infants and young children caused by endemic conditions such as the pneumonia-diarrhea complex. Variations in death rates among cities were explainable by differences in socioeconomic measures, except among southern cities, in which the proportion of blacks living in extreme poverty was an important variable (Crimmins and Condran 1983).

In the course of the eighteenth and nineteenth centuries, then, there was a shift from epidemics afflicting people of all ages to endemic infectious diseases afflicting primarily infants and children. The change occurred earlier in the North than the South, although by the 1920s and 1930s, malaria was in decline south of the Mason—Dixon line. In the course of the twentieth century, the pneumonia-diarrhea complex continued to decline as economic conditions continued to improve, literacy increased, and public health measures were strengthened. By the 1930s tuberculosis and other infectious diseases caused fewer deaths than cardiovascular diseases and cancer. This change was unrelated to medical therapy, for until the late 1930s such therapy had no discernible effect on mortality (Omran 1977). At that time, however, first sulfonamides and then antibiotics were introduced. The result was a small but measurable impact on mortality rates. In the last seven years of the pre-chemotherapy era (1930-7) the age-adjusted mortality rate declined an average of 4.28 deaths per 100,000 population per year. From 1937 through 1954, when antibiotics became widely available, the age-adjusted rate declined on average 19.4 deaths per 100,000 population. From 1955 through 1968 the decline all but ceased, averaging 2.1 deaths per 100,000 population per year. At the time many people argued that the decline had ceased because infectious diseases had ceased to be a significant cause of death, and the noninfectious and human-made causes of death were refractory to any intervention. It will be recalled that the same explanation was given for the diminution in the mortality decline in Latin America. Beginning in the late 1960s, however, the decline resumed. From 1968 to 1978 the average annual decline was 11.8 deaths per 100,000 population, and this decline has continued to persist (McDermott 1981).

The decline in mortality since the late 1960s has been accompanied by a shift to later and later ages at death, a pattern sufficiently unusual that some observers have claimed it represents a new and previously undescribed stage of epidemiological history (Olshansky and Ault 1986). The debates generated have been about several issues. First, what has caused the decline in mortality since the late 1960s: medical care, changes in behavior, or environmental changes? There is no doubt that early, widespread, and vigorous treatment of hypertension has had a measurable impact on the prevalence of that condition. Presumably that is reflected in a decreasing number of deaths from cardiovascular disease. There have also been changes in smoking patterns, the consumption of meat, and the degree to which people exercise.

Second, is survival to older and older ages accompanied by improvements in morbidity and level of function? On one hand are those who argue that there is a finite life span of about 85 years; that more and more people are living that long in a healthy state; and that they will then die of "natural causes" without lingering illnesses. This has been called the "rectangu-larization" of the mortality and morbidity curves (Fries and Crapo 1981). On the other hand are those who argue that 85 does not seem to be the upper limit to the human life span; that the survival of more and more people to older and older ages will be accompanied by a disproportionate increase in disability and morbidity; and that the presence of lingering chronic conditions will impose an enormous cost on the health care system (Schneider and Brody 1983).

Finally, what causes of death have been responsible for most of the decline in mortality at older ages? Although cardiovascular conditions are generally implicated, sorting out causes among chronically ill people with multiple health problems is often difficult.

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