How ants know the queen is dead?
Edited from the transcript for readability:
Ants have this local communication where they drop pheromones and they can change nearby ant states that can smell a pheromone and say "Oh food is nearby" or "it's time to attack" or "time to do nesting" instinct.
So they have this very elaborate horizontal propagation of information through pheromones, but they do this other thing called trophallaxis, what happens is an ant will come up to another one and basically vomit up food and then the other ant slips it up, so ants in fact have two stomachs, they have this private stomach and they have the social stomach that they share the food with every other hand now what this ends up being it's their global variables it's like a global bulletin board system for the entire colony. For instance the Queen generates this very particular chemical that no other ant produces and she does trophallaxis just like all the other ants and what happens is over the course of maybe two hours that little trace of chemical will disseminate through the entire colony and if that chemical ever evaporates because the Queen died or was lost the entire ant colony instantly knows that they've lost their queen and then they actually start a whole new behavior promoting a new queen. So ants actually have a balance of communication here between the global and local the way they propagate information.