Punctualism

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Punctualism, below, consists of morphological stability and rare bursts of evolutionary change.

The Punctuated Equilibrium ( English equilibrium punctuated , abbreviated jargon Punk Eek ) is one of the American paleontologist Niles Eldredge and Stephen Jay Gould first time in 1972 presented theory which, starting from Ernst Mayr's theory of allopatric speciation an explanation of discontinuous change rates and jumps delivers Fossil ranks.

theory

The theory turns against phyletic gradualism , which, according to Gould and Eldredge, assumes a slow and constant transformation of biological species. In contrast to this, in punctualism, a period of time called "stasis" (standstill), in which species show only a small amount of morphologically noticeable change, alternates with rapid change during allopatric speciation ("rapid" change is there because it refers to geological time periods, not necessarily "fast" for human conditions in the sense of everyday use). "Stasis" is broken through (English. Punctuated ).

One consequence of punctualism is a critical attitude towards strictly adaptive explanations for the morphology , biochemistry or behavior of living things , which are often rejected as "just so stories". In addition, non-adaptive mechanisms such as gene drift and spandrel formation must also be taken into account from a point-by-point perspective .

Closely related to this is the idea of ​​the unpredictability of biological evolution : If the wheel of time were turned back to a certain natural historical epoch, a completely different development would result.

Punctualism has often been misinterpreted as a modern version of a volatile evolution, similar to that advocated by Richard Goldschmidt in the first half of the 20th century ( Hopeful Monster ). SJ Gould has contradicted this interpretation, emphasized that punctualism stands within the framework of the synthetic theory of evolution , and specifically denied a reference between punctualism and Goldschmidt's hypothesis. As a gradualism with a variable speed of development, punctualism is widely accepted today. To this day, however, the relative importance of selective mechanisms is still a matter of dispute. The discussion is increasingly being conducted in relation to specific groups of organisms, since it is becoming more and more evident that evolutionary mechanisms studied in a species or genus cannot be generalized very much.

See also

literature

  • N. Eldredge, SJ Gould: Punctuated equilibria: an alternative to phyletic gradualism. In: T. Schopf (Ed.), Models in Paleobiology, 82-115, Freeman, Cooper and Co., San Francisco, (1972); Reprinted in: N. Eldredge, Time frames, Princeton Univ. Press, Princeton, NJ, 1985, 193 as PDF

Individual evidence

  1. ↑ "... punctuated equilibrium only confirms all the belief and predictions of the Modern Synthesis." SJ Gould in "The Structure of Evolutionary Theory" (2002) pp. 1001/1002
  2. ↑ ibid. P. 1007
  3. ↑ Ernst Mayr "What Evolution is." (2001) p. 270, ISBN 3-442-15349-2

Web links