Speaking of health knowledge, here's an interesting abstract that compares health recommendations from books written in the 1920s, 1930s, and 1940s to advice today. Fascinating idea. Some books were right, even back then. Some, less so. My favorite:
Inconsistencies or discrepancies between historical and current health knowledge and recommendations will also be presented. For example of historical health knowledge that is inconsistent with current comes from Burkard, Chambers, & Maroney's 1936 book entitled Health by Doing, “Teachers and parents . . . know that the use of tobacco interferes with good attention and with learning.” This is inconsistent with indications from current neurology research that suggests that nicotine enhances mental alertness.Ah well, even back then, you couldn't be perfect.
This is a neat idea, comparing recommendations long ago to today. Too bad there aren't good surveys from that period of health knowledge.