Gregg Easterbrook proposes a thought experiment in The Progress Paradox, which went approximately like this: Would you agree to permanently trade places with a random person who lived X hundred years ago? Chances are: no you wouldn't.

(The book: http://www.amazon.com/Progress-Paradox-Better-While-People/d.... Related essay that I did almost 5 years ago: http://www.questioningchristian.com/2006/03/progress_hope_a....)

See also pg's 2004 comment: "… try living for a year using only the resources available to the average Frankish nobleman in 800, and report back to us. (I'll be generous and not send you back to the stone age.)" http://www.paulgraham.com/gap.html