...I prefer to have younger workers. So if they don't live into their useless 70's, I don't mind very much.

But without medinine level your villagers will become elderly very early! the most they live longer the most they are young longer. When I have a runner, with level 3 of medicine, he runs until he's 66 years old! with the level 2 he stops running around 55 y/o! (I think)