An average life expectancy of 40 doesn't mean that you were likely to reach 40 and then keel over. More people died young, and this brought down the average. But if you made it past childhood, and didn't die in childbirth, you could expect to live to a fair age. And it's not ancient history either - that's how it still works in poor countries.

When I looked at my son's maths homework when he was at school I could never make head nor tail of what they were talking about in the questions. I'd have had a much better chance with the alleged 1895 exam paper. Apart from some of the stuff about American History.