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a process in which something passes by degrees to a different stage (especially a more advanced or mature stage)
selection by humans for breeding of useful traits from the natural variation among different organisms
(physiology) the responsive adjustment of a sense organ (as the eye) to varying conditions (as of light)
a natural process resulting in the evolution of organisms best adapted to the environment
the remains (or an impression) of a plant or animal that existed in a past geological age and that has been excavated from the soil
a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulus
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