BioConcepts

constraintZwang (ger.)

• 1) The material structure or configuration of parts in a system that has a harnessing, channelling or controlling influence on the flow of energy within the sytem, e.g. the body of an organism serving as a boundary condition for physical laws and providing the basis for the organism as an integrated autonomous system.  
  category organism

  1829

  Die Bewegung eines Systems materieller, auf was immer für eine Art unter sich verknüpfter Punkte, deren Bewegungen zugleich an was immer für äußere Beschränkungen gebunden sind, geschieht in jedem Augenblick in möglich größter Übereinstimmung mit der freien Bewegung, oder unter möglich kleinstem Zwange, indem man als Maaß des Zwanges, den das ganze System in jedem Zeittheilchen erleidet, die Summe der Produkte aus dem Quadrate der Ablenkung jedes Punkts von seiner freien Bewegung in seine Maße betrachtet.

  Gauss, C.F. (1829). Über ein neues allgemeines Grundgesetz der Mechanik. Journal für die reine und angewandte Mathematik 4, 232-235: 233.

  1904

  [In] non-holonomic dynamical systems […] the number of independent coordinates […] required in order to specify the configuration of the system at any time is greater than the number of degrees of freedom of the system, owing to the fact that the system is subject to constraints which will be supposed to do no work, and which are expressed by a number of non-integrable kinematical relations

  Whittaker, E.T. (1904). A Treatise on the Analytical Dynamics of Particles and Rigid Bodies: 210.
  

  1967

  the non-holonomic constraints or “transmission code” must be completely specified in order to define the stored hereditary information.

  Pattee, H.H. (1967). Quantum mechanics, heredity and the origin of life. J. theoret. Biol. 17, 410-420: 413.

  1967

  Through their results, dynamics modify the setting for subsequent dynamics. Dynamically created forms, if somehow consolidated, become molds for the course of future activity. […] [W]ere the development of every part or branch allowed to pursue its own capricious course without constraints, without a frame of integral interdependencies, we could not have trees […] that we could categorize distinctly by their shapes as oakes or pines or poplars even though each specimen is individually unique.

  Weiss, P. (1967). 1 + 1 ≠ 2 (One plus one does not equal two). In: Quarton G.C., Melnechuk, T. & Schmitt, F.O. (eds.). The Neurosciences, 801-821: 804; 808-9.

  1968

  a classical physical representation of a classification process must depend on non-holonomic constraints, that is, on structures which allow more degrees of freedom in the state description than is available for the actual dynamic motion of the system. At the molecular level this would imply that non-holonomic constraints allow a larger number of energetically possible reactions than the number of reactions which are actually available to the dynamics of the system

  Pattee, H.H. (1968). The physical basis of coding and reliability in biological evolution. In: Waddington, C.H. (ed.). Towards a Theoretical Biology, vol. 1, 77-93: 79. 

  1970

  we must recognize the essential characteristic of hierarchical organization, that the collective constraints which affect the individual elements always appear to produce some integrated function of the collection. In other words, out of the innumerable collective interactions of subunits which constrain the motions of individual subunits, we recognize only those in which we see some coherent activity. In common language we would say that hierarchical constraints produce specific actions or are designed for some purpose.

  Pattee, H.H. (1970). The problem of biological hierarchy. In: Waddington, C.H. (ed.). Towards a Theoretical Biology, vol. 3, 117-136: 125.

  1971

  Co-ordination in biological organisms takes the form of hierarchical control levels which at each level provide greater and greater freedom or adaptability for the whole organism by selectively adding more and more constraints to its component parts. […] Life is distinguished from inanimate matter by the co-ordination of its constraints. The fundamental function of this co-ordination is to allow alternative descriptions to be translated into alternative actions. The basic example of this function is the co-ordinated set of macromolecules which executes the genetic coding. It is useful to think of such co-ordinated constraints as generalized language structures that classify the detailed dynamical processes at one level of organization according to their importance for function at a higher level.

  Pattee, H.H. (1971). Physcial theories of biological co-ordination. Quartery Review of Biophysics 4, 255-276: 256; 273.

  1972

  Hierarchical control systems […] involve specific constraints on the motions of the individual elements. In a control hierarchy the collective upper level structures exert a specific, dynamic constraint on the details of motion on individuals at the lower level, so that the fast dynamics of the lower level cannot simply be averaged out. This amounts to a feedback path between two structural levels. Therefore, the physical behavior of a control hierarchy must take into account at least two levels at a time, and furthermore the one-particle approximation fails because the constrained subunits are atypical. […] Some of these constraints are of obvious physical origin such as the restriction of spatial freedom by neighboring cells of the collection. Such structural contraints may cause cells to stop growing and replicating because of simple overcrowding or lack of food. But these restrictions are not different from those found in a growing crystal. The control constraints, on the other hand, limit the individual cells’ freedom in a very different way. We observe that as the collection of cells grows, certain groups of cells alter their growth patterns, depending on their positions in the collection, but not because of any direct physical limitation in food or space. The control constraintappears in the form of a message or instruction which turns off or on specific genes in the individual cells.

  Pattee, H.H. (1972). The nature of hierarchical controls in living matter. In: Rosen, R. (ed.). Foundations of Mathematical Biology, vol. 1, 1-22: 4. 

  1972

  A natural law is inexorable and incorporeal, whereas a constraint can be accidental or arbitrary and must have some distinct physical embodiment in the form of a structure. […] Constraints, unlike laws of nature, must be the consequence of what we call some form of material structure, such as molecules, membranes, typewriters, or table tops […].The reason that constraints are not redundant or inconsistent with respect to the laws of motion is that they are alternative descriptions of the system. Con­straints originate because of a different definition or classification of the system boundaries or system variables even though the equations of constraint may be in the same mathematical form as equations of motion. Our usual justification for choosing to use such auxiliary conditions in place of the detailed dynamics is that it simplifies our description of the behavior of the system.

  Pattee, H.H. (1972). Laws and constraints, symbols and languages. In: Waddington, C.H. (ed.). Towards a Theoretical Biology, vol. 4, 248-258: 249.

  1973

  a dynamical collection is described as a constraint when there exist equations or rules in a simpler form that direct or control the motions of selected particles. […] an equation of constraint in physics i[s] an alternative description of the microscopically complex and deterministic motions that gains in simplicity or utility by selectively ignoring certain dynamical details. In effect, the physicist has classified or coded the microscopic degrees of freedom into a smaller number of new variables.

  Pattee, H.H. (1973). The physical basis and origin of hierarchical control. In: Pattee, H.H. (ed.). Hierarchy Theory. The Challenge of Complex Systems, 71-108: 88

  1990

  the information necessary to ensure the systems identity during self-reproduction is stored in some components acting as a blueprint or record. They specify the construction of the constraints harnessing the system dynamics. Thus the information required to maintain the systems identity is not homogeneously distributed in the whole network of components, but materialized in some specialized ones […] some of the constraints constructed by means of the information stored in the record-components are also necessary to interpret that information functionally. […] In certain conditions the operational closure of the system allows the appearance of mechanisms of internal control, which enable, at the same time, the development of more complex forms of autonomy.

  Moreno, A., Fernandez, J. & Etzeberria, A. (1990). Cybernetics, autopoiesis, and definition of life. In: Trappl, R. (ed.). Cybernetics and Systems ’90, 357-364: 362.

  1994

  [in] recurrent chemical networks that maintain the circular organization of the system, the production of new components plays the role of internal constraints. Instead of a global constraint here we witness the appearance of new local constraints created by the localized action of certain components, in such a way that the stability of the organization forms is linked to individual components.

  Moreno, A., Umerez, J. & Fernandez, J. (1994). Definition of life and the research program in artificial life. Ludus Vitalis 2, 15-33: 17.

  1996

  Simply put, the form of an organism represents a series of “material constraints” on the activity of that organism. Animals are put together the way they are because of the invariant unfolding of necessary laws. And their construction, according to these laws, serves as a “constraint” on the possible physiology and ecology of the organism. Function is the “effect” of form because the form or structure of an organism represents the “boundary conditions” on element potentials. These boundary conditions are not immaterial essences exerting their “molding” or “shaping” force on fluctuating matter. They are themselves purely material levels of organization which have a limiting influence on the “activity” of animal physiology and ecology.

  Asma, T.S. (1996). Following Form and Function: 58.

  2000

  autonomous organisation is only possible if it generates constraints that modulate the flows of energy so that those constraints are re-generated, and contribute in this way to the recursive maintenance of the organisation.

  Ruiz-Mirazo, K & Moreno, A. (2000). Searching for the roots of autonomy: The natural and artificial paradigms revisited. Comunication and Cognition-Artificial Intelligence 17, 209-228: 213-4.

  2000

  we confront a virtuous cycle: Work constructs constraints, yet constraints on the release of energy are required for work to be done. Here is the heart of a new concept of “organization” that is not covered by our concepts of matter alone, energy alone, entropy alone, or information alone.

  Kauffman, S. (2000). Investigations: 4.

  2015

  our central thesis is that organisational closure should be understood as closure of constraints, a regime of causation which is at the same time distinct from – and related to – the underlying causal regime of thermodynamic openness. […] biological self-determination occurs in the form of self-constraint […] the organisation of the constraints can be said to achieve self-determination as self-constraint, since the conditions of existence of the constitutive constraints are, because of closure, mutually determined within the organisation itself.

  Montévil, M. & Mossio, M. (2015). Biological organization as closure of constraints. Journal of Theoretical Biology 372, 179-191: 180; 181.

  2015

  constraints do not produce their effect by transmitting energy and/or matter to the process or reaction, but rather by channeling and harnessing a thermodynamic flow, without being subject to that flow. […] the constraint can be pertinently described as a structure which channels a source of energy […]. Constraints are irreducible to the thermodynamic flow, and constitute for this reason a distinct regime of causation.

  Moreno, A. & Mossio, M. (2015). Biological Autonomy. A Philosophical and Theoretical Enquiry: 15.

• 2) Pathways in the evolutionary transformation of structures or the result of these pathways that are determined by the organisms’ mode of life.
  category evolution

  1937

  [Einer der Hauptgründe für die Entstehung von Unzweckmaßigkeiten aber liegt in der ,,Orthogenese“, dem „Entwicklungs-Zwang“ der Organismen.

  Frankenberg, G. von (1937). Unzweckmäßigkeit im Organismenreich. Natur und Museum 67, 521-533: 525.]

  1943

  Beispiele lassen sich in großer Zahl finden, wenn man die Fälle heraussucht, in denen ein einheiticher Entwicklungszwang vorliegt, aber verschiedene Wege zu seiner Verwirklichung offenstehen. So entwickelten sich z.B. parallel und unabhängig voneinander in den verschiedensten Klettertiergattungen Greifhände

  Rensch, B. (1943). Die paläontologischen Evolutionsregeln in zoologischer Betrachtung. Biologia Generalis 17, 1-55: 41. 

  1947

  [Es gilt], daß weder die Organisation der Tierkörper noch die jeweiligen Umweltverhältnisse eine völlig beliebgige Entwicklung zulassen, sondern dass hier Einschränkungen vorliegen, die sich in vielen Fällen direkt als Entwicklungszwang auswirken. Beispiele dafür bietet jede Tiergruppe. Es handelt sich vor allem um viele analoge Organentwicklungen und Konvergenzen

  Rensch, B. (1947). Neuere Probleme der Abstammungslehre: 65. 

• 3) Structures determining the development and evolutionary path of an organism or lineage of organisms.
  category evolution

  1979

  constraints restrict possible paths and modes of change so strongly that the constraints themselves become much the most interesting aspect of evolution

  Gould, S.J. & Lewontin, R.C. (1979). The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proc. Roy. Soc. London Ser. B 205, 581-598: 594.

  1985

  Some constraints arise from the hill-climbing nature of the evolutionary processes underlying adaptation

  Maynard Smith, J. et al. (1985). Developmental constraints and evolution. Quart. Rev. Biol. 60, 265-287: 270.

  1985

  A developmental constraint is a bias in the production of variant phenotypes or a limit of phenotypic variability caused by the structure, character, composition, or dynamics of the developmental system

  Maynard Smith, J. et al. (1985). Developmental constraints and evolution. Quart. Rev. Biol. 60, 265-287: 266.

  1989

  structures from two individuals or from the same individual are homologous if they share a set of developmental constraints, caused by locally acting self-regulatory mechanisms of organ differentiation

  Wagner, G.P. (1989). The biological homology concept. Ann. Rev. Ecol. Syst. 20, 51-69: 62.

  1993

  mammals came to pursue similar life-styles to dinosaurs, not because dinosaurs vacated habitable ecological spaces, but because of the structural constraints operating on functional vertebrate bodies.

  Masters, J.C. & Rayner, R.J. (1993). Competition and macroevolution: the ghost of competition yet to come? Biological Journal of the Linnean Society 49, 87-98: 95.

  2003

  Constraints are attributes of living systems and as such, they arise, evolve, and eventually disappear. In other words, constraints have phylogenetic continuity. […] we can define constraint as a mechanism or process that limits or biases the evolutionary response of a character to external selection acting during the focal life stage

  Schwenk, K. & Wagner, G.P. (2003). Constraint. In: Hall, B.K. & Olson, W.M. (eds.). Key Words and Concepts in Evolutionary Developmental Biology, 52-61: 56; 58.