Evolution

You may be looking for the novel.

Evolution was the development and change of organisms over time. It is closely linked to mutation and natural selection, although specifically it is a long-term process of adaptation over time.

On Earth, a human scientist, Charles Darwin, "discovered" and popularised the idea. (AUDIO: Bloodtide)

Notable instances

Davros wished to determine the ultimate evolution of the Kaled race and to direct it. The result of this was the Daleks. (TV: Genesis of the Daleks) After escaping the Battle of Canary Wharf, Dalek Sec and the Cult of Skaro arrived in 1930s New York. Dalek Sec wished to determine the ultimate evolution of the Daleks, which resulted in the human-Dalek. (TV: Daleks in Manhattan / Evolution of the Daleks)

Light and the Reverend Ernest Matthews separately found the concept abhorrent, though for different reasons, the former because of his love of stasis and hatred of change, the latter because he found it repugnant to have evolved from monkeys. (TV: Ghost Light)

Professor Richard Lazarus had created a machine that rejuvenated himself, or, in simpler terms, a machine that allowed him to make himself younger. This transformation also accidentally unlocked a rejected option for human evolution, making him a scorpion-like mutant. (TV: The Lazarus Experiment)

The Time Lords evolved over time into what they were at the time of the Time War, through prolongued exposure to the Time Vortex. River Song was experimented on to have similar characteristics after having been conceived in the Vortex. (TV: A Good Man Goes to War)

The Seventh Doctor told Ace that examples of actual evolution are quite rare in Earth science, and that the universe was big enough for all the conflicting theories of species development to have some validity. (PROSE: Cat's Cradle: Witch Mark)