Volume

Spot on, Lim. So much that is "exotic" translates to someone doing it hard one way or another. Mind you, the fact is that we need to be careful not to be temporally myopic. When I was a lad in Australia, porters and farmers and laborers heaved 180 pound (82kg) bags of wheat around all day. In the 1950s, the bag weight was reduced to 50kg, and then to 40kg. A lot of old laborers had very bad backs -- and they never made much money either.

Terrific picture, though. It really tells the story.