A story of public health that needs to be remembered and constantly relearnt

I took this from Roy Porter’s The Greatest Benefit to Mankind: A Medical History of Humanity, a marvellous book. In 1821 the City of Paris published a massive demographic study of the city Recherches statistiques sur la ville de Paris [Statistical Researches on the City of Paris]. An ex-army surgeon René Louis Villermé, an early advocate of what we now call public health, was invited to analyse the study to learn lessons for health. Villermé found big differences in the mortality of different arrondissements, and he set out to discover why. He started with favourites of the time for explaining mortality differences: environmental factors like altitude, soil, and climate. He found no relationship, which is not surprising as the differences in such measures between the arrondissements must be tiny and would be barely statistically detectable even if they were the cause. (I’m reminded by Geoffery Rose, the great epidemiologist pointing out that if you studied the cause of lung cancer…