There's a Heifer in Your Tank is a neat agriculture site oriented to young folks. They cover interesting things that most take for granted. This PDF of theirs contains nice information about the evolution of head cheese. They also have something on stress and meat quality.
And something on how pork has changed over time. There's a neat photo in there of a chop from the 1940s. That's roughly what Mangalitsa looks like today (see photo above).
Given how much pork has changed, I really don't understand how recipes from 1940s or before could work with today's lean pork.
Of course, that lardy pork used to cost a lot. Fat takes roughly 3x as many calories to produce as protein. Pork tasted much better in the 1940s, but most people didn't eat much of it. It was too dear.
That black and white photo is from a set with the description:
"Noonday dinner, family-style, at restaurant in Muskogee, Oklahoma. The price of this dinner was fifteen cents. It included a medium-sized serving of meat, sliced tomatoes, beans, corn on the cob, potatoes, dumplings, corn bread and butter, tea and coffee, various jellies and preserves and onions. All you wanted of everything except the meat."