Understanding Darwinian Evolution

Understanding Darwinian Evolution Published 1859

1) Common Descent—All of life on earth emerged

from a few common ancestors This controversial claim put humans on a level plane with other living species. 2) Gradualism--The change of a species takes more

than several generations (the notion of evolution put forth by Jean Baptiste Lamarck). This controversial claim suggested that the earth was much older than initially suspected.

3) Population Speciation--Change in a species is

fragmented and not ubiquitous to that species. While Lamarck claimed that all giraffes living under tall trees would develop long necks-Darwin suggested that only some giraffes would randomly be born with these traits.

4) Natural selection—Certain randomly acquired

traits are beneficial. Giraffes with longer necks can reach more food, and are therefore more wellnourished and healthy. These giraffes are better equipped to survive, and thus are more likely to mate, and to pass the long neck trait on to their offspring.

Brought to you by the Secular Student Alliance. www.secularstudents.org