Swarm Intelligence in Nature-- Part I

In nature, the swarm behavior is divided into two categories: "Species", in which individuals form a swarm in order to profit in a certain way, and "Social Insects" -which live in societies- which its members aren't able to survive alone.

1. Social Insects: 

We though long time ago that social insects are more intelligent that solitary insects, by looking at complex tasks they are able to accomplish. In fact, even though they cannot be qualified as individually intelligent, members of these societies are capable of making such sophisticated constructions collectively, and of adapting themselves to changing environments, to search for the shortest path to a foraging area (figure)

Ants find the shorter path in an experimental setup. A bridge leads from a nest to a foraging area. (a) 4 minutes after bridge placement. (b) 8 minutes after bridge placement. (c) Distribution of percentage of ants who chose the shorter path.

Many collective activities in which it's sophistication exceeds the simple capacities of each individual. "Who leads? Who makes orders, foresees the future, elaborates plans and guarantees an equilibrium?," wrote Maeterlinck. It's in fact a confusing question.

 Each insect in the colony of social insects seems to have its own agenda, for example, ants are capable of choosing the shorter path to go from a nest to a foraging area because of mechanisms of resource collecting.

In the same way, French Pierre-Paul Grassé has discovered that during the construction of a termite nest, these insects started their activity by laying down pellets of mud but in a random way with a greater probability of laying it where there is already another pellet, and with no coordination. However, once these collected pellets reach a certain density in a limited space, they become a significant stimulus that motivates more and more termites to lay down this material in such a way that pillars and vaults, and later the entire nest are constructed. Grassé has used the term stigmergy to describe this particular type of indirect communication in which "the coordination of tasks and the regulation of constructions doesn't depend directly on workers but rather on the construction itself." The principal characteristics which differentiates from other forms of communication:

•  It's an indirect and non-symbolic form of communication, through the modification of the environment, thus, we can use the term "indirect social interaction" to describe this phenomenon.
• The stigmergic information has a local range, only insects visiting the place where it was produced have access to it.

Termite nest © Masson.

 Another example, in order to find food, bees have constantly to search in vast areas and fly long distances. When a bee finds a new foraging site, it returns immediately to the hive and inform other members of the colony. A little time later, other bees start to fly around the source.

Bees hive © Camazine.

Bees are deaf and thus can't establish communications via sound. Nevertheless, they are capable of communicating without difficulty the location of a foraging site to other members of the colony. The methods they use are rather extraordinary, Von Frisch discovered that bees express themselves not only via touch and taste, but also via dancing; they describe the location of a remote site by dancing. All the information other bees need to find the foraging site, its distance from the hive, its direction, the productivity, is encoded in this dance.


Once a new foraging site is localized, the bee returns to the hive and starts repeating specific movements in a way that attract the attention of other bees.
All the information they need regarding the new foraging site can be obtained by the general behavior of the bee.