Vestigial structures
Natural selection
a natural process resulting in the evolution of organisms best adapted to the environment
Adaptation
(physiology) the responsive adjustment of a sense organ (as the eye) to varying conditions (as of light)
Charles Darwin
English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
Homologous structures
Structures in different species that are similar because of common ancestry.
Evolution
a process in which something passes by degrees to a different stage (especially a more advanced or mature stage)
Vestigial structures
remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.
Common ancestor
the shared ancestor of new, different species that arose from one population