In developmental psychology

Developmental psychology

Developmental psychology, also known as human development, is the scientific study of systematic psychological changes, emotional changes, and perception changes that occur in human beings over the course of their life span. Originally concerned with infants and children, the field has expanded to...

, developmental systems theory (DST) is an overarching theoretical perspective on biological development, heredity

Heredity

Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...

, and evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 . It emphasizes the equal contributions of genes

Gênes

Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...

, environment, and epigenetic

Epigenetics

In biology, and specifically genetics, epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence – hence the name epi- -genetics...

 factors on developmental processes. DST, unlike conventional scientific theories, is not directly used to help make predictions for testing experimental results; instead, it is seen as a collection of philosophical, psychological, and scientific models

Scientific modelling

Scientific modelling is the process of generating abstract, conceptual, graphical and/or mathematical models. Science offers a growing collection of methods, techniques and theory about all kinds of specialized scientific modelling...

 of development and evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

. As a whole, these models argue the inadequacy of modern evolutionary views

Modern evolutionary synthesis

The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...

 on the roles of genes and natural selection

Natural selection

Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

 as the principle explanation of living structures. Developmental systems theory embraces a large range of positions that expand biological explanations of human development and hold modern evolutionary theory as a misconception of the nature of living processes.

Overview

All versions of developmental systems theory espouse the view that:

• All biological process
  Biological process
  A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....
  
  es (including both evolution and development) operate by continually assembling new structures.

• Each such structure
  Structure
  Structure is a fundamental, tangible or intangible notion referring to the recognition, observation, nature, and permanence of patterns and relationships of entities. This notion may itself be an object, such as a built structure, or an attribute, such as the structure of society...
  
   transcends the structures from which it arose and has its own systematic characteristics, information, functions and laws.

• Conversely, each such structure is ultimately irreducible to any lower (or higher) level of structure, and can be described and explained only on its own terms.

• Furthermore, the major processes through which life
  Life
  Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased , or else because they lack such functions and are classified as inanimate...
  
   as a whole operates, including evolution
  Evolution
  Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
  
  , heredity and the development of particular organisms, can only be accounted for by incorporating many more layers of structure and process than the conventional concepts of ‘gene
  Gene
  A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
  
  ’ and ‘environment
  Natural environment
  The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
  
  ’ normally allow for.

In other words, although it does not claim that all structures are equal, development systems theory is fundamentally opposed to reductionism

Reductionism

Reductionism can mean either an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can...

 of all kinds. In short, developmental systems theory intends to formulate a perspective which does not presume the causal (or ontological) priority of any particular entity and thereby maintains an explanatory openness on all empirical fronts. For example, there is vigorous resistance to the widespread assumptions that one can legitimately speak of genes ‘for’ specific phenotypic characters or that adaptation consists of evolution ‘shaping’ the more or less passive species, as opposed to adaptation consisting of organisms actively selecting, defining, shaping and often creating their niches.

Six Themes of DST

1. Development is a product of multiple interacting sources
2. Development depends on the current state of the organism
3. The notion of Extended Inheritance, the idea that an organism inherits resources rather than just genes
4. Development as a mechanistic process of construction, where the organism helps shape its own environment
5. The notion of Distributed Control, the idea that no single source of influence has central control over an organisms development
6. The evolution of an entire developmental system, not just of a particular population

A computing metaphor

To adopt a computing metaphor, the reductionists whom developmental systems theory opposes assume that causal factors can be divided into ‘processes’ and ‘data’. Data (inputs, resources, content, and so on) is required by all processes, and must often fall within certain limits if the process in question is to have its ‘normal’ outcome. However, the data alone is helpless to create this outcome, while the process may be ‘satisfied’ with a considerable range of alternative data. Developmental systems theory, by contrast, assumes that the process/data distinction is at best misleading and at worst completely false, and that while it may be helpful for very specific pragmatic or theoretical reasons to treat a structure now as a process and now as a datum, there is always a risk (to which reductionists routinely succumb) that this methodological convenience will be promoted into an ontological conclusion. In fact, for the proponents of DST, either all structures are both process and data, depending on context, or even more radically, no structure is either.

Fundamental asymmetry

For reductionists there is a fundamental asymmetry between different causal factors, whereas for DST such asymmetries can only be justified by specific purposes, and argue that many of the (generally unspoken) purposes to which such (generally exaggerated) asymmetries have been put are scientifically illegitimate. Thus, for developmental systems theory, many of the most widely applied, asymmetric and entirely legitimate distinctions biologists draw (between, say, genetic factors that create potential and environmental factors that select outcomes or genetic factors of determination and environmental factors of realisation) obtain their legitimacy from the conceptual clarity and specificity with which they are applied, not from their having tapped a profound and irreducible ontological truth about biological causation. One problem might be solved by reversing the direction of causation correctly identified in another. This parity of treatment is especially important when comparing the evolutionary and developmental explanations for one and the same character of an organism.

DST approach

One upshot of this approach is that developmental systems theory also argues that what is inherited from generation to generation is a good deal more than simply genes (or even the other items, such as the fertilised zygote, that are also sometimes conceded). As a result, much of the conceptual framework that justifies ‘selfish gene’ models is regarded by developmental systems theory as not merely weak but actually false. Not only are major elements of the environment built and inherited as materially as any gene but active modifications to the environment by the organism (for example, a termite mound or a beaver’s dam) demonstrably become major environmental factors to which future adaptation is addressed. Thus, once termites have begun to build their monumental nests, it is the demands of living in those very nests to which future generations of termite must adapt.

This inheritance may take many forms and operate on many scales, with a multiplicity of systems of inheritance complementing the genes. From position and maternal effects on gene expression to epigenetic inheritance to the active construction and intergenerational transmission of enduring niches, development systems theory argues that not only inheritance but evolution as a whole can be understood only by taking into account a far wider range of ‘reproducers’ or ‘inheritance systems’ – genetic, epigenetic, behavioural and symbolic – than neo-Darwinism

Neo-Darwinism

Neo-Darwinism is the 'modern synthesis' of Darwinian evolution through natural selection with Mendelian genetics, the latter being a set of primary tenets specifying that evolution involves the transmission of characteristics from parent to child through the mechanism of genetic transfer, rather...

’s ‘atomic’ genes and gene-like ‘replicators’. DST regards every level of biological structure as susceptible to influence from all the structures by which they are surrounded, be it from above, below, or any other direction – a proposition that throws into question some of (popular and professional) biology’s most central and celebrated claims, not least the ‘central dogma’ of Mendelian genetics, any direct determination of phenotype by genotype, and the very notion that any aspect of biological (or psychological, or any other higher form) activity or experience is capable of direct or exhaustive genetic or evolutionary ‘explanation’.

Developmental systems theory is plainly radically incompatible with both neo-Darwinism and information processing theory. Whereas neo-Darwinism defines evolution in terms of changes in gene distribution, the possibility that an evolutionarily significant change may arise and be sustained without any directly corresponding change in gene frequencies is an elementary assumption of developmental systems theory, just as neo-Darwinism’s ‘explanation’ of phenomena in terms of reproductive fitness is regarded as fundamentally shallow. Even the widespread mechanistic equation of ‘gene’ with a specific DNA sequence has been thrown into question, as have the analogous interpretations of evolution and adaptation.

Likewise, the wholly generic, functional and anti-developmental models offered by information processing theory are comprehensively challenged by DST’s evidence that nothing is explained without an explicit structural and developmental analysis on the appropriate levels. As a result, what qualifies as ‘information’ depends wholly on the content and context out of which that information arises, within which it is translated and to which it is applied.

Related theories

Developmental systems theory is by no means a narrowly defined collection of ideas, and the boundaries with neighbouring models are very porous. Notable related ideas (with key texts) include:

• Baldwinian selection, or the Baldwin effect
  Baldwin effect
  The Baldwin effect, also known as Baldwinian evolution or ontogenic evolution, is a theory of a possible evolutionary processes that was originally put forward in 1896 in a paper, "A New Factor in Evolution," by American psychologist James Mark Baldwin. The paper proposed a mechanism for specific...
  
  
• Dialectical biology
• Evolutionary developmental biology
  Evolutionary developmental biology
  Evolutionary developmental biology is a field of biology that compares the developmental processes of different organisms to determine the ancestral relationship between them, and to discover how developmental processes evolved...
  
  
• General systems theory
• Neural Darwinism
  Neural Darwinism
  Neural Darwinism, a large scale theory of brain function by Gerald Edelman, was initially published in 1978, in a book called The Mindful Brain...
  
  
• Probabilistic epigenesis

See also

• Living systems theory
• Developmental psychobiology
  Developmental psychobiology
  Developmental psychobiology is an interdisciplinary field, encompassing developmental psychology, biological psychology, neuroscience and many other areas of biology. The field covers all phases of ontogeny, with particular emphasis on prenatal, perinatal and early childhood development...
  
  

Further reading

• Baldwin, J.M. (1895). Consciousness and evolution. Science 2, 219-223
• Baldwin, J.M. (1896a). A new factor in evolution. American Naturalist 30, 441–451, 536–553.
• Baldwin, J.M. (1896b). Development and Evolution. New York: Macmillan.
• Bertalanffy, L. von (1950). The theory of open systems in physics and biology. Science 3: 23-9.
• Bertalanffy, L. von (1971). General System Theory. London: Allen Lane.
• Dawkins, R. (1976). The Selfish Gene. New York: Oxford University Press.
• Dawkins, R. (1982). The Extended Phenotype. Oxford: Oxford University Press.
• Depew, D.J. and Weber, B.H. (1995). Darwinism Evolving. System Dynamics and the Genealogy of Natural Selection. Cambridge, Mass.: MIT Press.
• Edelman, G.M. (1987). Neural Darwinism: Theory of Neuronal Group Selection. New York: Basic Books.
• Edelman, G.M. and Tononi, G. (2001). Consciousness. How Mind Becomes Imagination. London: Penguin.
• Eigen, M. (1992). Steps Towards Life. Oxford: Oxford University Press.
• Goodwin, B.C. (1995). How the Leopard Changed its Spots. London: Orion.
• Goodwin, B.C. and Saunders, P. (1992). Theoretical Biology. Epigenetic and Evolutionary Order from Complex Systems. Baltimore: Johns Hopkins University Press.
• Gray, R.D. (2000). Selfish genes or developmental systems? In Singh, R.S., Krimbas, C.B., Paul, D.B., and Beatty, J. (2000). Thinking about Evolution: Historical, Philosophical, and Political Perspectives. Cambridge University Press: Cambridge. (184-207).
• Jablonka, E., and Lamb, M.J. (1995). Epigenetic Inheritance and Evolution. The Lamarckian Dimension. London: Oxford University Press.
• Kauffman, S.A. (1993). The Origins of Order: Self-Organization and Selection in Evolution. Oxford: Oxford University Press.
• Koestler, A., and Smythies, J.R. (1969). Beyond Reductionism. London: Hutchinson.
• Lehrman, D.S. (1953). A critique of Konrad Lorenz’s theory of instinctive behaviour. Quarterly Review of Biology 28: 337-363.
• Levins, R. and Lewontin, R. (1985). The Dialectical Biologist. London: Harvard University Press.
• Lewontin, R.C. (2000). The Triple Helix: Gene, Organism and Environment. Harvard University Press: Cambridge, Mass.
• Neumann-Held, E.M. (1999). The gene is dead- long live the gene. Conceptualizing genes the constructionist way. In P. Koslowski (ed.). Sociobiology and Bioeconomics: The Theory of Evolution in Economic and Biological Thinking, pp. 105–137. Berlin: Springer.
• Oyama, S. (2000). The Ontogeny of Information: Developmental Systems and Evolution, Second Edition. Durham, N.C.: Duke University Press.
• Oyama, S., Griffiths, P.E., and Gray, R.D. (2001). Cycles of Contingency: Developmental Systems and Evolution. Cambridge, Mass.: MIT Press.
• Thelen, E. and Smith, L.B. (1994). A Dynamic Systems Approach to the Development of Cognition and Action. Cambridge, Mass.: MIT Press.
• Waddington, C.H. (1957). The Strategy of the Genes. London: Allen and Unwin.

External links

• Developmental Systems Theory Development website with some further links, 2007.
• William Bechtel, Developmental Systems Theory and Beyond presentation, winter 2006.