Condition of a system which requires energy and/or information from a host system from which it depends totally for its survival, with out any benefit for its host.
Ectoparasites perforates the boundary subsystem of their host, fixing themselves on the outer side of the boundary. Endoparasites introduce themselves into some inner subsystem of their host.
The parasite differs form the symbiont or the commensal, which are beneficial or neutral for their hosts.
A. RAPOPORT comments: "As a rule, parasites introduced from the outside can be combated by the immunological reactions of the host against the biochemically 'foreign' invaders…. In general, successful parasitism depends on a simulation by the parasite of characteristics that the host 'recognizes' (mistakenly) as its own" (1969, p.25).
Parasitism also can be social, as seen by numerous examples in insect societies… and possibly in human ones, where some groups live off the social production without retribution in any visible way.
In parasitic situations, "what one group gains is what another group loses", as stated by MARUYAMA, who considers this a zero-sum game. This author describes also symbiosis as a positive-sum game and mutual destruction (mutual "antibiosis"), a negative-sum game (1976, p.204).
However, in many cases this is merely a transient situation, as when the parasite destroys or kills the host, bringing about its own elimination. Parasites escape from this fate only if their parasitic state is permanently tolerable for the host, or if they are a phase of a cycle affecting succesively various hosts, or if they have a life cycle with a phase of autonomous life.
Recentlty C. ZIMMER gave a number of examples where apparently strict parasitism can be useful for the host in some quite covert and unexpected way.
He also observed that some parasites are able to subtly manipulate their host's behavior for their own ends (2000 and M. RIDLEY's review, 2000, p.48-9).
In both situations, parasitism fosters adaptation and, in ZIMMER's view, even probably evolution. It would be interesting to find out more about this mechanism, even possibly between groups in human societies.
- 1) General information
- 2) Methodology or model
- 3) Epistemology, ontology and semantics
- 4) Human sciences
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Bertalanffy Center for the Study of Systems Science (2020). Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]
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