nutrition, advances in public health, and education; for populations at large, higher spending on health care has had minimal impacts on mortality.

Historically, inadequate food production and the resulting malnutrition compromised adult productivity. For example, data from the United Kingdom show that, until the late eighteenth century, U.K. agricultural production could only feed 80 percent of the population. Greater output raised nutritional status, leading to longer working hours, while parallel investments in public health improved the use of the calories consumed (Fogel 2002). Fogel (1986) concludes that nutritional improvements have contributed about 40 percent to the decline in mortality since 1700, with sharp rises in nutritional status occurring in periods of abundant food, mostly in the twentieth century.

Along with better nutrition, advances in hygiene and education have played a more important role in reducing mortality than advances in medicine. McKeown, Record, and Turner (1962, 1975) examine the reasons for mortality declines in England and Wales during the nineteenth and twentieth centuries. Mortality was affected by medical measures such as immunizations, but lower exposure to infection, expanded access to piped water and sanitation, and better nutrition were the major factors explaining the rising survival rate. Reduction in death from air-borne infections occurred before the introduction of effective medical treatment, and better nutrition had a large effect on the ability to ward off infection and on the probability of death. Declines in mortality from water- and food-borne diseases could be traced to improved hygiene and better nutrition, with treatment emerging as largely irrelevant.

Similarly, Fuchs (1974), in his study of infant mortality reductions in New York City between 1900 and 1930, attributed these shifts mainly to rising standards of living, education, and lower fertility, rather than to medical advances. Fogel (2002) compares morbidity levels in the post– Civil War period in the United States with those in the latter part of the twentieth century and finds that morbidity levels have fallen significantly, partly because of changes in lifestyle and partly because of other factors including medical interventions. Lleras-Muney (2005) examines the determinants of life expectancy in the United States using a synthetic cohort beginning in 1900. Her estimates indicate that each year of education increases life expectancy at age 35 by as much as 1.7 years, a very significant increase that suggests the central importance of education. Similar findings are reported in multiple studies in developing countries (Schultz 2002).

Exceptions are breakthroughs in pharmaceutical therapies after the 1940s—notably vaccines, penicillin, and other antibiotics that penicillin spawned—that changed the health landscape. Acemoglu and Johnson (in Spence and Lewis, forthcoming) also point to the development of the pesticide DDT, which effectively controlled disease vectors like mosquitoes, and to the establishment of the World Health Organization, which helped to spread knowledge about, and methods for, the adoption of technologies that helped to reduce mortality. The contribution of medical advances to either morbidity or mortality is more difficult to trace and to attribute directly. This is because it is difficult to isolate the effect of individual procedures, whose successful application depends on many factors.<sup>2</sup>

> 2. Limited data for specific interventions, differences in patients’ health when treated, and high variability in the medical treatment across medical facilities that complement and influence successful application of new medical technologies, among other things, make it difficult to determine the contribution of new medical procedures. Cost-

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