Morphic field

The theory of morphic fields conjectured that all living beings hade a field associated with them which defined their entire biology. Morphic fields provided a force that guided the development of an organism as it grew, making it take on a form similar to other species. DNA was not the source of structure itself, but rather a "receiver" that translated instructions in the field into physical form.

Morphic fields were reinforced by every successive generation. That is why there were so many humanoid races in the Universe. The Gallifreyans were the first sentient life to evolve in the universe, and so created a morphic field for humanoids. That made it more probable that the next race to evolve would be humanoid, and that made it much more likely that the following race would be humanoid, and so on. The majority of the non-humanoid races developed in environments where two legs, two arms and a head would have been a positive handicap.

The "Angels" were capable of manipulating morphic fields using machinery within Belial. They used it to turn themselves into energy beings. (NA: Lucifer Rising)

The Blessing was connected to the morphic field of humanity, particularly around Shanghai and Buenos Aires. In those two cities, the people around the Blessing always had the same lifespan as the world average. In 2011, the Three Families were able to change all of humanity by inserting Jack Harkness' immortal blood at both ends, disrupting the morphic field, turning everyone immortal and starting Miracle Day. (TW: The Gathering, The Blood Line) Jack Harkness guessed from the start that a disturbance in the morphic field was likely responsible for Miracle Day. (TW: Rendition)

The Jauza adapted morphic field technology for military application. (BNA: Another Girl, Another Planet)

The Tonska were researching a temporal rift, trying to find a way to allow the Yed-Prior Zaniah to be immortal. When Menkib was experimentally destroyed, they were unable to recreate his morphic field and he was turned into a Cerunnos. (VD: ...And Eternity in an Hour)

Behind the scenes

 * The theory of morphic fields and resonance originated as a serious real world scientific proposal which was pioneered by Rupert Sheldrake PhD. However, most in the scientific community do not accept the idea and regard it as a fringe science or pseudoscience.