Afghanistan, Nov. 11 -- Watch people in a shopping line, at a bus stop or on a busy street, and you will probably spot it within minutes: a smartphone tucked into the back pocket of someone's jeans, its top half sticking out above the denim.
Few people think about the habit. The phone comes out to check a message or take a call, then slides straight back into the same place. No bag to open, no backpack to dig through, and both hands stay free.
For most of their history, back pockets held wallets, combs and folded papers. Today they also carry a device that does far more than any of those things, and because most phones are bigger than a wallet, they are much harder to miss.
The back pocket is almost as old as jeans themselves. When Levi ...