Biology
homologous structures
Homologous structures are similar structures that serve different functions, such as a human's arm, a dog's leg, a bird's wing, and a whale's fin, which look similar but serve different purposes. Homologous structures point to a common ancestor and support evolution.
natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Adaptation
A trait that helps an organism survive and reproduce
Catastrophism
A principle that states that geologic change occurs suddenly
Evolution
Change over time
Charles Darwin
English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
artificial selection
Selection by humans for breeding of useful traits from the natural variation among different organisms
Cambian Explosion
The rapid diversification of multicellular animal life around the beginning of the Cambrian Period, resulting in the appearance of almost all modern animal phyla.
Gradualism
The theory that evolution occurs slowly but steadily
Fitness
ability to survive and reproduce
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.
analogous structures
similarities among unrelated species that result from convergent evolution