Common descent is a theory that states that all organisms are descendants of a single common ancestor.
Explanation:
Common Descent:
By definition, common descent signifies the common ancestry of a group of organisms.
Common descent is an approach to explain the similarities between different organisms.
The theory of common descent states that all organisms have descended from one common ancestor and therefore, possess some degree of similarity.
Common descent has helped explain the genetic and structural similarities between two entirely different organisms such as reptiles and birds.
For example, pentadactyl limbs i.e. limb with five fingers or digits is a highly conserved characteristics of all tetrapods. This indicates common descent with modification.
