“Nothing in biology makes sense except in the light of evolution.” —Theodosius Dobzhansky
Evolution is the concept of biological change in which species accumulate variation in their traits from their ancestors as they adapt to new environments over time. Evolution explains both biological diversity and unity among organisms; affirms scientific data (including fossil evidence), extinction events, and according theory; and disputes the classical belief of perfection in creation.
Evolution is studied from a microscopic or a macroscopic standpoint both within and across species over time. Regardless of type, evolution is a slow, gradual process which occurs repeatedly over thousands of years that affects the genetic pool of generations of organisms. The concept of evolution was developed following a long history of philosophical thought and viewpoints on the nature and development of biological species.