smart swarm

is an excellent book by Peter Miller (isbn 978-0-00-738297-2). As usual I'm going to quote from a few pages:
As successful foragers return to the nest with seeds, they're met at the nest entrace by foragers waiting in reserve. This contact stimulates the inactive ants to go out. Foragers normally don't come back until they find something. So the faster the foragers return, the faster other ants go out, enabling the colony to tune its work force to the probability of finding food.
Instead of attempting to outsmart the desert environment, the ants, in a sense, were matching its complexity with their own.
Instead of trying to keep fine-tuning a system so it will work better and better, maybe what we really ought to be looking for is a rigourous way of saying, okay, that's good enough. [Deborah Gordon]
If a scout bee was impressed by another scout's dance, she might fly to the box being advertised and conduct her own inspection, which could last as long as an hour. But she would never blindly follow another scout's opinion by dancing for a site she hadn't visited.
J. Scott Turner considers the mound's function as a respiratory system so essential that the termites couldn't live without it. In a sense, he argues, the mound is almost a living part of the colony.
If individuals in a group are prompted to make small changes to a shared structure that inspires others to improve it even further, the structure becomes an active player in the creative process.
Unlike our systems, which are tuned for efficiency, the termites' systems have been tuned for robustness, which they demonstrate by building mounds that are constantly self-healing.
What really made the lights go on was the realization that termites don't pay attention to the environment itself but to changes in the environment.
Not only does this complicated structure represent an indirect collaboration among millions of individuals, it also embodies a kind of ongoing conversation between the colony and the world outside. The mound might look like a structure, but it's better thought of as a process.
We should think of it [the termite mound] as a dynamic system that balances forces both inside and outside its walls to create the right environment for the termites.
When you feel like you belong to something, it gives you so much more freedom and so much more energy that might otherwise be used up in anxiety, to do other things.
On January 12, 2006, several hundred thousand pilgrims had gathered in a dusty tent city at Mina, three miles east of Mecca...
By noon... about a half-million or more pilgrims filled the Jamarat plaza in front of the bridge... The pressure inside the crowd was crushing... More than an hour later, victims were piled up seven layers deep: 363 men and women were dead.
"Those in charge need to remember the root cause of the problem: too many people trying to get through too small a space. The ingress rate at the bridge was 135,000 per hour. The thoughput rate of the pillars was only 100,000 an hour. You can't put a pint into a half-pint jug." [Keith Still]