If we look back 100-200 years, we find it hard to believe that people in civilized countries like the United States and Great Britain actually lived the way that they did. It offends us that slavery was condoned and practiced, and that life was so primitive. Children worked long hours in factories in appalling conditions, and some factories were literally death traps with locked doors. Doctors and barbers drew blood to cure us of disease, and most infections led to death or amputation in a population whose life expectancy ranged in the 40’s to 50’s. If we go forward 100...