Many misunderstand that period of time, they were highly hygienic (for their understanding of such things) they washed their hands before eating, they used shared food containers very hygienically (no double dip, no using something that was already in your mouth to serve the next food, no scratching your face at the table with your hand, etc). People also think most were dead by 30ish, many lived til their 70s and 80s but so many more didn't make it out of childhood that keeps the average age down. There is a great yt chan where the host talks about all this and much more, can't remember his chan atm but if there is interest I can track it down and link it.