Wednesday, August 14, 2013

A quote from Lewontin

Richard Lewontin, 1979. One can go and nitpick on the rest of his letter; but what would be interesting really is a refutation of what Lewontin claims to be facts below, leaving aside his extrapolations. That is, the statements below are not true; or that he has failed to mention significant other facts that change how we would interpret these statements.

In 1828, when causes of death were first systematically recorded in Britain, the death rate from tuberculosis was nearly 4,000 per million. The rate can only be appreciated in contrast to the present death rate in the US and Britain from all causes of only 9,000 per million. By 1855 the death rate from tuberculosis had fallen to about 2,700 and continued to fall steadily so that by the turn of the century it had reached about 1,200 per million. Koch’s discovery of the causal bacillus in the 1880s had no effect whatsoever on the rate of decline, and by 1925, after the Flexner revolution in medical schools, the rate was about 800, only 20 percent of its value in 1838. Totally unaffected by the arrival of modern medicine, the death rate continued its steady drop to 400 per million until 1948 when the introduction of chemotherapy on a broad scale did indeed accelerate the decline to its present negligible level. It is important to note that 57 percent of the decline had occurred by 1900 and 90 percent of the decline had occurred by the time of the introduction of chemotherapy. Extrapolation of the trend predicts that by 1970 death from tuberculosis would have reached its present low value even in the absence of chemotherapy.

The history of tuberculosis is the history of nearly all the major killers of the nineteenth century. Whooping cough, scarlet fever, and measles, all with death rates in excess of 1,000 per million children, and bronchitis, all declined steadily with no observable effect of the discovery of causative agents, of immunization or of chemotherapy. The sole exception was diphtheria which began its precipitous decline in 1900 with the introduction of anti-toxin and which was wiped out in five years after the national immunization campaign. The most revealing case is that of measles which killed about 1,200 in every million children in the nineteenth century. By 1960, despite the complete absence of any known medical treatment, it had disappeared as a cause of death in Britain and the US while in much of Africa it remains the chief cause of death of children.

The causes of the tremendous decline of mortality from infectious diseases in the last 100 years are not certain. All that is certain is that “scientific medicine” played no significant part. Water supply and sanitation are not involved, since water-borne diseases have not been the major killers. The suggestion that a reduction in crowding may have reduced the rate of transmission of respiratory diseases is not altogether convincing, since measles remains pandemic although it kills virtually no one in advanced countries. The most likely explanation, both for the historical trend and for the differences between regions of the world today, is in nutrition, although hard evidence is not easy to come by.