John T. Wood's Mental Tools Page

Historical Contingency

While the mechanisms driving the evolution of organismal structuress follow deterministic laws...

The resulting structures are the product of a historical sequence of events in which environmental context and spatiotemporal contingencies determine the outcome of specific mechanistic events.

Evolutionary outcomes are path dependent and usually irreversible.

"Contingency is the affirmation of control by immediate events over destiny..."
(Stephen Jay Gould, 1989, p. 284)

"Charles Darwin recognized this central distinction between laws in the background and contingency in the details..."
(Stephen Jay Gould, 1989, p.290)

"...with the theory of evolution, as with statistical thermodynamics, the notion of contingency became established in the very heart of nature. Since Newton, physics had been based on a rigid determinism, which extended to all the sciences. Evolutionary theory and statistical thermodynamics completely transformed the way of looking at nature, mainly because they brought together and gave the same status of related and measurable quantities to order and chance - two concepts which until then had been incompatible"
(Francois Jacob, 1976, quoted in Dubrovsky, 2002, pp. 2)

"Gould (1993) appropriately distinguishes between that is referred to as contingency and the notion of chance. Pure chance precludes any explanation of particulars, but contingency, while denying that predictions can be made with confidence at the outset, does assert the possibility of explanation after a particular history has unfolded. Contingency represents the historian's mode of knowability; pure chance denies that particulars can be explicated at all (Gould, 1993). However, chance, far from being the same as indeterminacy, obeys a type of lawfulness or determination; the laws of chance (Bunge, 1999)."
(Dubrovsky, 2002, pp. 2)

"The problems of biology are not only the problems of an accurate description of the structure and function... ,but also the problem of their history. Organisms have history at two levels. Each one of us began life as a single fertilized egg cell which underwent processes of growth and transformation... In addition to their individual life stories, organisms have a collective history that started three billion years ago with rudimentary agglomerations of molecules, that has now reacthed its halfway point with tens of millions of diverse species, and that will end three billion years from now when the Sun consumes the Earth in a fiery expansion."
(Lewontin, 1995, pp. 118)

"Any consideration of historical events necessarily demands that we confront the relation between the system that is the object of our study and the penumbra of circumstances in which it is embedded, what is inside and what is outside."
(Lewontin, 1995, pp. 120)

"... the development of most organisms is a consequence of a unique interaction between their internal state and their external milieu. At every monment in the life history of an organims there is contingency of development such that the next step is dependent on the current state of the organism and the environmental signals that are impinging on it. Simply, the organismis a unique result of both its genes and the temporal sequence of environments through which it has passed, and their is no way of knowing in advance, from the DNA sequence, what the organism will look like, except in general terms."
(Lewontin, 1995, pp. 124)

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