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Stigmergy ( ) is a mechanism of indirect coordination, through the environment, between agents or actions. The principle is that the trace left in the
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
by an individual action stimulates the performance of a succeeding action by the same or different agent. Agents that respond to traces in the environment receive positive fitness benefits, reinforcing the likelihood of these behaviors becoming fixed within a population over time. Stigmergy is a form of
self-organization Self-organization, also called spontaneous order in the social sciences, is a process where some form of overall order arises from local interactions between parts of an initially disordered system. The process can be spontaneous when suffi ...
. It produces complex, seemingly intelligent structures, without need for any planning, control, or even direct communication between the agents. As such it supports efficient collaboration between extremely simple agents, who may lack memory or individual awareness of each other.


History

The term "stigmergy" was introduced by French biologist
Pierre-Paul Grassé Pierre-Paul Grassé (November 27, 1895 in Périgueux (Dordogne) – July 9, 1985) was a French zoologist, writer of over 300 publications including the influential 52-volume ''Traité de Zoologie''. He was an expert on termites and one of the las ...
in 1959 to refer to
termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...
behavior. He defined it as: "Stimulation of workers by the performance they have achieved." It is derived from the Greek words στίγμα ''stigma'' "mark, sign" and ἔργον ''ergon'' "work, action", and captures the notion that an agent’s actions leave signs in the environment, signs that it and other agents sense and that determine and incite their subsequent actions. Later on, a distinction was made between the stigmergic phenomenon, which is specific to the guidance of additional work, and the more general, non-work specific incitation, for which the term ''sematectonic'' communication was coined by
E. O. Wilson Edward Osborne Wilson (June 10, 1929 – December 26, 2021) was an American biologist, naturalist, entomologist and writer. According to David Attenborough, Wilson was the world's leading expert in his specialty of myrmecology, the study of an ...
, from the Greek words σῆμα ''sema'' "sign, token", and τέκτων ''tecton'' "craftsman, builder": "There is a need for a more general, somewhat less clumsy expression to denote the evocation of any form of behavior or physiological change by the evidences of work performed by other animals, including the special case of the guidance of additional work." Stigmergy is now one of the key concepts in the field of
swarm intelligence Swarm intelligence (SI) is the collective behavior of decentralized, self-organized systems, natural or artificial. The concept is employed in work on artificial intelligence. The expression was introduced by Gerardo Beni and Jing Wang in 1989, in ...
.Parunak, H. v D. (2003)
"Making swarming happen."
In Proc. of Conf. on Swarming and Network Enabled Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR), McLean, Virginia, USA, January 2003.


Stigmergic behavior in non-human organisms

Stigmergy was first observed in
social insects Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping genera ...
. For example,
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...
s exchange information by laying down
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s (the trace) on their way back to the nest when they have found food. In that way, they collectively develop a
complex network In the context of network theory, a complex network is a graph (network) with non-trivial topological features—features that do not occur in simple networks such as lattices or random graphs but often occur in networks representing real s ...
of trails, connecting the nest in an efficient way to various food sources. When ants come out of the nest searching for food, they are stimulated by the pheromone to follow the trail towards the food source. The network of trails functions as a shared external memory for the ant colony. In computer science, this general method has been applied in a variety of techniques called
ant colony optimization In computer science and operations research, the ant colony optimization algorithm (ACO) is a probabilistic technique for solving computational problems which can be reduced to finding good paths through graphs. Artificial ants stand for mult ...
, which search for solutions to complex problems by depositing "virtual pheromones" along paths that appear promising. In the field of
artificial neural network Artificial neural networks (ANNs), usually simply called neural networks (NNs) or neural nets, are computing systems inspired by the biological neural networks that constitute animal brains. An ANN is based on a collection of connected unit ...
s, stigmergy can be used as a computational memory. Federico Galatolo showed that a stigmergic memory can achieve the same performances of more complex and well established neural networks architectures like
LSTM Long short-term memory (LSTM) is an artificial neural network used in the fields of artificial intelligence and deep learning. Unlike standard feedforward neural networks, LSTM has feedback connections. Such a recurrent neural network (RNN) c ...
. Other
eusocial Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generat ...
creatures, such as
termites Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...
, use pheromones to build their complex nests by following a simple
decentralized Decentralization or decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or delegated away from a central, authoritative location or group. Conce ...
rule set In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing c ...
. Each insect scoops up a 'mudball' or similar material from its environment, infuses the ball with pheromones, and deposits it on the ground, initially in a random spot. However, termites are attracted to their nestmates' pheromones and are therefore more likely to drop their own mudballs on top of their neighbors'. The larger the heap of mud becomes, the more attractive it is, and therefore the more mud will be added to it (positive feedback). Over time this leads to the construction of pillars, arches, tunnels and chambers. Stigmergy has been observed in
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
, various species of which differentiate into distinct cell types and which participate in group behaviors that are guided by sophisticated temporal and spatial control systems. Spectacular examples of multicellular behavior can be found among the
myxobacteria The myxobacteria ("slime bacteria") are a group of bacteria that predominantly live in the soil and feed on insoluble organic substances. The myxobacteria have very large genomes relative to other bacteria, e.g. 9–10 million nucleotides except ...
. Myxobacteria travel in ''
swarm Swarm behaviour, or swarming, is a collective behaviour exhibited by entities, particularly animals, of similar size which aggregate together, perhaps milling about the same spot or perhaps moving ''en masse'' or migrating in some direction. ...
s'' containing many
cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...
s kept together by intercellular molecular
signals In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
. Most myxobacteria are predatory: individuals benefit from aggregation as it allows accumulation of extracellular
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s which are used to digest prey microorganisms. When nutrients are scarce, myxobacterial cells aggregate into ''fruiting bodies'', within which the swarming cells transform themselves into dormant myxospores with thick cell walls. The fruiting process is thought to benefit myxobacteria by ensuring that
cell growth Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than ...
is resumed with a group (swarm) of myxobacteria, rather than isolated cells. Similar life cycles have developed among the cellular
slime mold Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic mu ...
s. The best known of the myxobacteria, ''
Myxococcus xanthus ''Myxococcus xanthus'' is a gram-negative, rod-shaped species of myxobacteria that exhibits various forms of self-organizing behavior in response to environmental cues. Under normal conditions with abundant food, it exists as a predatory, saproph ...
'' and ''
Stigmatella aurantiaca ''Stigmatella aurantiaca'' is a member of myxobacteria, a group of gram-negative bacteria with a complex developmental life cycle. Classification The bacterial nature of this organism was recognized by Thaxter in 1892, who grouped it among the ...
'', are studied in various laboratories as
prokaryotic A prokaryote () is a Unicellular organism, single-celled organism that lacks a cell nucleus, nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek language, Greek wikt:πρό#Ancient Greek, πρό (, 'before') a ...
models of development.


Analysis of human behavior

Stigmergy studied in
eusocial Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generat ...
creatures and physical systems, has been proposed as a model of analyzing some
robotics Robotics is an interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. Robotics integrat ...
systems, multi-
agent Agent may refer to: Espionage, investigation, and law *, spies or intelligence officers * Law of agency, laws involving a person authorized to act on behalf of another ** Agent of record, a person with a contractual agreement with an insuranc ...
systems, communication in
computer networks A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ma ...
, and
online communities An online community, also called an internet community or web community, is a community whose members interact with each other primarily via the Internet. Members of the community usually share common interests. For many, online communities may fe ...
. On the
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
there are many collective projects where users interact only by modifying local parts of their shared virtual environment.
Wikipedia Wikipedia is a multilingual free online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and using a wiki-based editing system. Wikipedia is the largest and most-read refer ...
is an example of this. The massive structure of information available in a
wiki A wiki ( ) is an online hypertext publication collaboratively edited and managed by its own audience, using a web browser. A typical wiki contains multiple pages for the subjects or scope of the project, and could be either open to the pu ...
,Infoworld: A conversation with Steve Burbeck about multicellular computing
or an
open source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open ...
project such as the
FreeBSD kernel FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...
could be compared to a
termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...
nest; one initial user leaves a seed of an idea (a mudball) which attracts other users who then build upon and modify this initial concept, eventually constructing an elaborate structure of connected thoughts. Heylighen F. (2007)
Why is Open Access Development so Successful? Stigmergic organization and the economics of information
, in: B. Lutterbeck, M. Baerwolff & R. A. Gehring (eds.), Open Source Jahrbuch 2007, Lehmanns Media, 2007, p. 165-180.
In addition the concept of stigmergy has also been used to describe how cooperative work such as building design may be integrated. Designing a large contemporary building involves a large and diverse network of actors (e.g. architects, building engineers, static engineers, building services engineers). Their distributed activities may be partly integrated through practices of stigmergy.


Analysis of human social movements

The rise of
open source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open ...
in the 21st century has disrupted the business models of some
proprietary software Proprietary software is software that is deemed within the free and open-source software to be non-free because its creator, publisher, or other rightsholder or rightsholder partner exercises a legal monopoly afforded by modern copyright and int ...
providers, and open content projects like Wikipedia have threatened the business models of companies like '' Britannica''. Researchers have studied collaborative open source projects, arguing they provide insights into the emergence of large-scale peer production and the growth of
gift economy A gift economy or gift culture is a system of exchange where valuables are not sold, but rather given without an explicit agreement for immediate or future rewards. Social norms and customs govern giving a gift in a gift culture; although there ...
.


Stigmergic society

Heather Marsh Heather Marsh is a philosopher, programmer and human rights activist. She is the author of the Binding Chaos series, a study of methods of mass collaboration. Internet and journalism In 2015 Marsh began working on a data project with a goal of ...
, associated with the
Occupy Movement The Occupy movement was an international populist socio-political movement that expressed opposition to social and economic inequality and to the perceived lack of "real democracy" around the world. It aimed primarily to advance social and econo ...
,
Wikileaks WikiLeaks () is an international Nonprofit organization, non-profit organisation that published news leaks and classified media provided by anonymous Source (journalism), sources. Julian Assange, an Australian Internet activism, Internet acti ...
, and Anonymous, has proposed a new social system where competition as a driving force would be replaced with a more collaborative society. This proposed society would not use
representative democracy Representative democracy, also known as indirect democracy, is a type of democracy where elected people represent a group of people, in contrast to direct democracy. Nearly all modern Western-style democracies function as some type of represen ...
but new forms of idea and action based governance and collaborative methods including stigmergy. "With stigmergy, an initial idea is freely given, and the project is driven by the idea, not by a personality or group of personalities. No individual needs permission (competitive) or consensus (cooperative) to propose an idea or initiate a project." Some at the Hong Kong
Umbrella Movement The Umbrella Movement () was a political movement that emerged during the Hong Kong democracy protests of 2014. Its name arose from the use of umbrellas as a tool for passive resistance to the Hong Kong Police's use of pepper spray to dispe ...
in 2014 were quoted recommending stigmergy as a way forward.


See also

*
Ant mill An ant mill is an observed phenomenon in which a group of army ants are separated from the main foraging party, lose the pheromone track and begin to follow one another, forming a continuously rotating circle, commonly known as a "death spiral" be ...
*
Biosemiotics Biosemiotics (from the Greek βίος ''bios'', "life" and σημειωτικός ''sēmeiōtikos'', "observant of signs") is a field of semiotics and biology that studies the prelinguistic meaning-making, biological interpretation processes, p ...
*
Extended mind thesis In philosophy of mind, the extended mind thesis (EMT) says that the mind does not exclusively reside in the brain or even the body, but extends into the physical world. The EMT proposes that some objects in the external environment can be part o ...
*
Path dependence Path dependence is a concept in economics and the social sciences, referring to processes where past events or decisions constrain later events or decisions. It can be used to refer to outcomes at a single point in time or to long-run equilibria ...
*
Spontaneous order Spontaneous order, also named self-organization in the hard sciences, is the spontaneous emergence of order out of seeming chaos. The term "self-organization" is more often used for physical changes and biological processes, while "spontaneous o ...
*
Swarm intelligence Swarm intelligence (SI) is the collective behavior of decentralized, self-organized systems, natural or artificial. The concept is employed in work on artificial intelligence. The expression was introduced by Gerardo Beni and Jing Wang in 1989, in ...
*
Watchmaker analogy The watchmaker analogy or watchmaker argument is a teleological argument which states, by way of an analogy, that a design implies a designer, especially intelligent design by an intelligent designer, i.e. a creator deity. The watchmaker analogy ...


References


Further reading

* * * * * {{World view Systems theory Self-organization