Punctuated Equilibrium

Punctuated equilibrium (also called punctuated equilibria) is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and geologically rapid events of branching speciation called cladogenesis. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another.

Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism, which states that evolution generally occurs uniformly and by the steady and gradual transformation of whole lineages (called anagenesis). In this view, evolution is seen as generally smooth and continuous. In 1972, paleontologists Niles Eldredge and Stephen Jay Gould published a landmark paper developing this theory and called it punctuated equilibria. Their paper built upon Ernst Mayr's theory of geographic speciation, I. Michael Lerner's theories of developmental and genetic homeostasis, as well as their own empirical research. Eldredge and Gould proposed that the degree of gradualism commonly attributed to Charles Darwin is virtually nonexistent in the fossil record, and that stasis dominates the history of most fossil species.

Read more about Punctuated EquilibriumHistory, Common Misconceptions, Criticism, Darwin's Theory, Supplemental Modes of Rapid Evolution, Social Theory, International Relations, Language Change

Other articles related to "punctuated equilibrium":

Dawkins Vs. Gould - Synopsis - Part III—The View From Harvard
... Firstly, punctuated equilibrium, in which new species arise by a split in a parental species, followed by geologically rapid speciation of one or both of the fragments ... Gould argued that punctuated equilibrium challenges the gradual change expected by extrapolationists ... then outlines in chapter 8 Gould and Eldredge's punctuated equilibrium hypothesis ...
Punctuated Equilibrium - Language Change
... Dixon has proposed a punctuated equilibrium model for language histories, with reference particularly to the prehistory of the indigenous languages of Australia and his objections to the proposed Pama ...
Saltation (biology) - Confusion With Punctuated Equilibrium
... It is a popular misconception that punctuated equilibrium is a saltationist theory, often mistaken for Richard Goldschmidt's hypothesis of "Hopeful Monsters." However, punctuated equilibrium refers instead to a ...

Famous quotes containing the word equilibrium:

    When a person hasn’t in him that which is higher and stronger than all external influences, it is enough for him to catch a good cold in order to lose his equilibrium and begin to see an owl in every bird, to hear a dog’s bark in every sound.
    Anton Pavlovich Chekhov (1860–1904)