I'm fascinated by flash mobs, those seemingly spontaneous group behaviors that certain groups of humans have begun to develop lately. Consider this example, in which people agree to meet in Grand Central Station only to freeze in place, producing much confusion and delight among bystanders.
You might think that flash mobs were invented by homo sapiens and I would agree that our species has certainly perfected the art form. However, the ability to come together as a collective and carry out a pre-determined set of steps, has been going on for a long time among the lowliest of creatures: the slime mold.
Flash mobs are a form of self-organization, a spontaneous collective behavior that arises due to interactions between the parts of which a group is made. These parts can be individual cells, individual humans, or anything, really. Either way, the result can be quite wonderful.
Here is a strangely moving film, produced using old movies from the lab of Princeton University's John Bonner, showing slime mold cells (or Dictyostelium discoideum, as they are more properly know) coming together into a sort of "cellular flash mob" after sending each other sets of chemical signals. The result is extraordinary and, dare I say, inspiring: