A Hand on a Shoulder

I ran across this clip on CNN of Bolivian peacekeepers distributing food to Haitians in the earthquake's aftermath.  The process contrasted so many other relief events we're used to seeing: masses of hands reaching skyward as boxes are tossed from the back of pickups, stampedes, broken bags of rice scattered across the ground.

What struck me was the scene at :30.  There is an orderly line and a UN soldier with his hand resting on the shoulder of the first man.  There's gotta be some crowd psychology going on there and I'd love to discuss it with someone who knows more than I.  Does that hand on the shoulder mean, "I understand you need help and I'm here?"  It certainly doesn't seem threatening.  Does it indicate to the rest of the line that "yes, there's a good chance you're getting fed today."  Does it provide the reassurance that boundaries mean order and order means confidence that my needs will be met?

A hand on a shoulder.  It can mean order in the midst of chaos.  It can mean the world to someone in need.  Who's shoulder is your hand on today?