Heredity, Natural Selection, and Evolution

Highlights of Evolution

What is gradualism?

In the seventeenth century, Archbishop James Ussher (1581–1656) of the Irish Protestant Church calculated from the Old Testament genealogies that Earth was created on Sunday, October 26, 4004 B.C.E. He was also able to calculate exact dates for when Adam and Eve were forced from Paradise (Monday, November 10, 4004 B.C.E.) and when Noah’s Ark touched down on Mt. Ararat (Wednesday, May 5, 1491 B.C.E.).

The Darwin-Wallace theory of evolution is based on gradualism—the idea that speciation occurs by the gradual accumulation of new traits. This would allow one species to gradually evolve into a different-looking one over many, many generations, which is the scale of evolutionary time.


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