Punctuated equilibrium is the theory that most species, once they arise, change relatively little for most of their existence, a state called stasis, and that the evolutionary change that does occur is concentrated in comparatively brief, geologically rapid bursts tied to speciation events, rather than accumulating steadily and gradually across a lineage's whole history. Niles Eldredge and Stephen Jay Gould proposed it in a 1972 paper, building on the biologist Ernst Mayr's existing model in which new species most often arise in small, geographically isolated populations at the edge of a parent species' range, where change can spread through a small gene pool quickly, then persist largely unchanged once the new population is established and widespread. The theory does not reject natural selection or gradual change within a population; it argues about the pace and distribution of that change over geological time, a distinction its own proponents and its critics, including Richard Dawkins, have disputed the size of ever since.
Facts
Proposed Year Proposed ByNiles Eldredge and Stephen Jay Gould 1 Connections
Belongs To
Critiqued By
Dawkins argued in his 1986 book The Blind Watchmaker that punctuated equilibrium, though a real and useful description of the fossil record's pattern, had been presented by its reception in the press as a sharper break from ordinary neo-Darwinian gradualism than the theory itself actually claims, calling Eldredge and Gould modified gradualists rather than genuine saltationists. This atlas records the exchange as the reverse side of the same dispute Gould pressed against gene-centred adaptationism, neither position resolved here as the winner.
Source The Blind Watchmaker (Dawkins, 1986)Richard Dawkins
Proposed By
Sources
1. Niles Eldredge (Britannica)
Encyclopaedia Britannica
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