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