Descent: 7a. The fact of “descending” or being descended from an ancestor or ancestral stock; lineage. b. of animals and plants; in Biology extended to origination of species ( EVOLUTION 6c). c. (figurative). Derivation or origination from a particular source.
Oxford English Dictionary
Thus, on the theory of descent with modification, the main facts with respect to the mutual affinities of the extinct forms of life to each other and to living forms, are explained in a satisfactory manner. And they are wholly inexplicable on any other view.
In the sense of this chapter, common usage of the term descent involves a set of factors, both material and temporal. Descent entails the existence of both an ancestral source, a process by which copies of that source are generated through time, and the resulting offspring of that source. The entities involved may be human beings reckoning their ancestry through their parents and grandparents, biological organisms undergoing evolutionary change, behaviors changing through time, versions of a computer program being modified for final release, or abstract systems of thought subjected to critique and amendment. Descent is thus a genealogical concept, an account of the persistence of a lineage of related entities through time. Furthermore, observation of the world and the more formal strictures of information theory imply that processes of copying are not perfect over