The pattern can be described as long periods of evolutionary stability with brief periods of rapid evolutionary change found (either periodically or randomly) along the timeline. It's validity for speciation is contentious, but the pattern of fits and starts in rates of change in evolutionary processes has been identified in several (natural and artificial) evolutionary systems. Many independent factors (either endogenous or exogenous) are sufficient for producing punctuated equilibria. Originally proposed by Stephen Jay Gould to explain patterns of new species in the fossil record that did not fit Darwin's principle of gradualism.
- Evolution, Adaptation