evolution /ev′əlo̅o̅″shən/ [L, evolvere, to roll forth] , 1. a gradual, orderly, and continuous process of change and development from one condition or state to another. It encompasses all aspects of life, including physical, psychological, sociological, cultural, and intellectual development, and involves a progressive advancement from a simple to a more complex form or state through the processes of modification, differentiation, and growth. 2. a change in the genetic composition of a population of organisms over time. 3. the appearance over long periods of time of new taxonomic groups of organisms from preexisting groups. Kinds include convergent evolution, determinant evolution, emergent evolution, organic evolution, orthogenic evolution, saltatory evolution. −evolutionist, n.
