The evolutionary biologist Robert Trivers published his influential theory of reciprocal altruism in 1971 to explain the emergence of cooperation in nature. For his part, Richard Dawkins memorably described Trivers’ theory a few years later in a single sentence–“You scratch my back, I’ll ride yours.” By the way, Prof. Trivers was just a wee grad student in biology when he wrote up his original reciprocal altruism paper, though the basic idea of reciprocity goes back to moral philosopher David Hume’s theory of conventions. (Look it up!)

Now, fast forward to 2014. Tiffany Yannetta recently interviewed Robert Samuel, a “professional line sitter” who lives and works in New York City.  The complete interview, What it’s like to be a professional line sitter, provides a fascinating glimpse into daily life in the City and is definitely worth reading. Here is one excerpt that caught our attention:

Ms Yannetta: What do you do when you have to go to the bathroom?

Mr Samuel: There’s a loyalty between people standing in line—an unspoken code, so to speak. In my experience of doing this, which is a little over a year and half, it’s never been a problem. No one’s going to say, “You move your feet you lose your space.” I just say, I’m going to the bathroom, and find the nearest Starbucks and offer to get them a coffee or something.

Hat tip (yet again): Master of the Internet, Tyler Cowen