How silly can you get? Consider living in a cave. Anyone who lives in a cave, probably with high humidity and improper protection from in-ground cold, with bugs and spiders crawling around and biting him, and probably without proper sanitary conditions, increases his odds of dying young. You can find people all over the poor countries of the world who die young because they drink downstream water from the upstream sewage dumpers. If anything, cave people were healthier than we are. Why? Because we'ed die in no time at all, from exposure, if we tried living like they did.