The so called “natural” experiments are the base of observational studies in epidemiology. They are conceptualised as cohort studies designed by nature. Since the times of John Snow comparing the cholera rates in those served by Southwark and Vauxhall water company with the ones of Lambeth many epidemiologists have used this approach in a very efficient and fruitful way. Although the way we name it as “natural” resembles more experimental and biological sciences than social ones, there is no reason why social epidemiologists cannot apply the same methodological tools to social and political changes. Not just biological nature design cohort studies, also social and political forces do it everyday.

In this number we publish, 10 years after the fall of the wall and the dissolution of the communist regimes in Europe, two papers that take advantage of these huge social and political changes in the way of the classic use of natural experiments found in the epidemiological literature. Ellen Nolte and her colleagues compare the basic statistics of child health in East and West Germany since reunification concluding even policy lessons for the future: “to improve infant mortality in Germany, policy measures should focus on preventive rather than curative measures.”

The same “natural” experiment, although in a different way, is opportunistically used by Martin Bobak and colleagues to supply more empirical evidence in the debate about the theories to explain inequalities in health. Taking advantage of the egalitarian distribution of income in the communist countries they have studied several material and behavioural variables in the Czech Republic concluding that for myocardial infarction materialist explanations for the observed educational gradient are unlikely.

But not just acute political changes can be studied using John Snow's inherited tools. Societies construct categories like those associated with gender, which have been understudied by epidemiology until very recently. Like the Londoners served separately by two water companies in 1860, societies build a cultural and political web of attributes around women and men that could be disentangled and understood using observational epidemiological methods. Coronary heart diseases have been a focus of gender based clinical epidemiological studies for the past 10 years. In this number G Engstroem et al, following this line of thought, assess the effect modification of smoking, hyperlipidaemia and diabetes with social variables in women. This study adds support to the notion of a different natural history of coronary heart diseases in men and women.

Our theory and methods section continues our tradition of offering space to papers to contribute to a new public health theoretical body. Van der Maesen and Nijhuis offer a new piece for the debate on the philosophical foundations of modern public health. In their paper they propose a taxonomy of four different approaches to public health theory and hence public health action. Pareto, Weber, Marx and Durkheim philosophies seem to explain in their opinion the underlying thinking regarding nature ontology, nature epistemology and the perspective on health. Following our tradition the pages of the journal are open for the continuation of this or similar debates.