I think over time you'll find that it's easier to get, at 1/2 speed, science before farming in easy and normal modes, and that you can pretty easily get level 3 medicine by their late 40's or early 50's. I get all the puzzles except the graveyard done before my peeps reach 58. Much harder to do this running in normal mode, and I suspect it can't (or is really difficult) be done before 58 at 2x. And I do that without slave driving them (I don't drag them back to the tech table or hurry them up)

In my last easy game, the oldest villager was 53 when 15 puzzles were completed.