It also took a while to notice the effects of cigarette smoking.
While tobacco was used by Europeans in some quantity since the early colonization of North America, it was the mass-production of cigarettes in the late 19th century that made heavy smoking a possibility for a large number of people. The first medical work showing a link between smoking and cancer came out in 1912 and 1929.
But smoking didn't get really huge in the U.S. until the mid-20th century, the era of mass media marketing of cigarettes (L.S./M.F.T.!); the British Doctors Study in 1956 was statistically pretty darned conclusive from a Bayesian standpoint, but was famously opposed by R. A. Fisher. Much of the later controversy on the subject of tobacco and cancer was manufactured by the tobacco industry, well after the matter was scientifically settled.
Sources:
http://en.wikipedia.org/wiki/Health_effects_of_tobacco_smoking
http://www.cdc.gov/tobacco/data_statistics/tables/economics/consumption/
http://en.wikipedia.org/wiki/British_Doctors_Study
Thanks for the update.
Nutrition is a case where we have to try to make the best possible use of the data we have no matter how terrible, because we have to eat something now to sustain us while we plan and conduct more experiments.
I want to apply Bayes theorem to make rational health decisions from relatively weak data. I am generally wondering how one can synthesize historical human experiences with incomplete scientific data, in order to make risk-adverse and healthy decisions about human nutrition given limited research.
Example question/hypothesis: Does gluten cause health problems (ie exhibit chronic toxicity) in non-coeliac humans? Is there enough evidence to suggest that avoiding gluten might be a prudent risk-adverse decision for non-coeliacs?
We have some (mostly in vitro) scientific data suggesting that gluten may cause health problems in non-coeliac humans (such as these articles http://evolvify.com/the-case-against-gluten-medical-journal-references/). Let's say for the sake of arguing, that I can somehow convert these studies into a non-unity likelihood ratio for gluten toxicity in humans (although suggestions are welcome here too).
However, we also have prior information that a population of humans has been consuming gluten containing foods for at least 10,000 years, without any blatantly obvious toxic effects. Is there some way to convert this observation (and observations like this) into a prior probability distribution?