I agree with diet having a lot to do with the increased egg production from 100 years ago. Considering that most people were subsistence farmers back then. Struggling to keep themselves and their livestock fed. Chickens and hogs were popular choices, because they could survive on low quality grain, scraps and what they could forage for themselves. I remember my parents, which are in their nineties. Telling me how they would check the distance between an older hen’s pelvic bones. To see if she was laying or not. When they decided to make chicken and dumplings or soup.