DENSITY (Critical)
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(1) |
| ID | ◀ 852 ▶ |
| Object type | General information, Human sciences, Methodology or model |
The minimal number of individuals under which no collective or social behavior can appear, or alternatively the excessive density in a sociosystem which triggers pathological collective behavior.
P.P. GRASSÉ observed that: “… on the occasion of the reconstruction of the nest by termites, there is a critical density of insects under which no structure can appear” (1959). He developed this model under the name of “stigmergy”
J.T. BONNER (1988) and J.A. SHAPIRO (1988) have documented a number of examples. Critical density is also a basic condition for the switch to swarming from solitary phase by migratory locusts as shown by UVAROV and FAURE in South Africa and the Belgian biologist H. BREDO in former Belgian Congo and in Central America (see J.P. HARROY: “La lutte anti-acridienne et Hans BREDO” (Académie Royale des Sciences d'Outremer, Bruxelles, 1985)
Critical densities phenomena also appear as a basic condition for the shaping and development of human settlements, as demonstrated by P. ALLEN (1982).
What is really critical seems to be the crowding effect when the distance between individuals is so reduced that a threshold is crossed where new interactive effects — whether constructive or destructive — become possible (see J. CALHOUN — 1962 and 1971).
Constructive behavior appear when numerous individuals coalesce into a system of higher level, and destructive behavior whenovercrowding sets in.
The psychological aspect of the effect has been considered by E.H. HALL (1966), and the social ones where already more or less perceived by some sociologists since the end of 19th century (S. SIGHELE: The criminal crowd (1892); G. LE BON: Psychology of the crowds (1895) and J. ORTEGA Y GASSET: The revolt of the masses (1929).
This very important characteristic of loose systems would deserve much more research.
The subject is also doubtless related to criticality and percolation, as for example in locusts swarms and lemmings collective self-destruction.
See also
Distance (Critical)