Communication and Language

Communication in animal swarms is restricted to concrete events in the present. The collective development of language provided humanity with a new tool to register and communicate past and future events as well as abstract concepts. All human languages follow Zipf’s law, indicating a common structure.

Of Bees and Flowers

Between bees and flowers there exists a mutualistic interaction, requiring cooperation between partners to assure the survival of both.

Complexity and Criticality

Complex systems and critical behavior in complex system are defined in terms of correlation between constituents in the medium, subject to screening by intermediate constituents. At a critical point, the correlation length diverges—as a result, one finds the scale-free behavior also observed for bird flocks. This behavior is therefore possibly a form of self-organized criticality.

The Onset of Connectivity

Placing identical finite sized objects randomly in a plane leads first to cluster formation, eventually to the formation of overall connection: this process is denoted as percolation. It is a geometric form of critical behavior, occurring with an abrupt onset. Such phenomena form the basis of many transitions, from Galaxy formation to the onset of electrical conductivity. The formation of locust swarms can be considered as such a process.

Kin Selection: My Sister’s Keeper

Female bees carry two sets of chromosomes, one from the mother, one from the father—they are diploid. Male bees (drones) carry only one set, inherited from the mother—they are haploid. As a result, the relation between sisters is closer than between a female worker and her possible offspring. This inheritance structure led to the caste scheme of bee colonies, with a single queen giving rise to all offspring, while the sterile female workers take over the child care, not having children of their own. By assuring the survival of the children of the queen, the worker females assure the passage of favorable genes better than by having children of their own.

Avian Aerodynamics

A bird in flight experiences four forces: wing flapping brings a forward thrust and an upward lift, while air resistance creates a drag and the weight of the bird a downward pull. In addition, the flow of air over the wings creates an upward pressure. A third source of motion arises from a coordination of wing flapping between adjacent birds, as discussed in the previous chapter.

The Way to Go

Animals define the shortest route between two points on the ground through swarm intelligence: the most used and/or the one requiring the least time. Ants define traffic rules for most efficient travel. Bees have developed a symbolic language (waggle dance) to communicate orientation relative to the sun and to define the distance to the point of interest.

The Rules of the Flock

Following the seminal work of T. Vicsek et al. (Budapest), mathematical models are formulated, based on next neighbor interactions (alignment of flight direction) leading to global correlations. Computer simulations of these models lead to behavior patterns very much like those observed in empirical studies of bird flocks. In particular, a transition from random motion to flock behavior is observed for sufficiently precise flight alignment, corresponding to sufficiently low temperature in spin systems.

Coupled Oscillators

Pendulums on a common basis become eventually synchronized, through transmission of swing frequency. Coupled electric oscillators show the same effect. The application of this effect to synchronized behaviour of insect swarms provided the crucial mechanism for the understanding of coherent light and sound emission by fireflies and crickets.

The Birds of Rome

With the help of high speed stereographic cameras and a computer analysis of the results, a team from the University of Rome provided first precision data of large starling flocks. They determined shape and correlation of the flocks as well as the local internal coordination between birds. The overall global patterns were thus shown to be the result of local interactions between six to seven nearest neighbors.