KEY CONCEPT There were theories of biological and geologic change before Darwin.

Early scientists proposed ideas about evolution. Evolution is the biological change process over long periods of time by which descendants come to differ from their ancestors. A species is a group of organisms that can reproduce and have fertile offspring.

There were many important naturalists in the 18th century. Linnaeus – A Swedish botanist: classification system from kingdom to species – he proposed some organisms were brought about by hybridization – speciation. Buffon – A French naturalist: species shared ancestors rather than arising separately – he proposed that the Earth was much older than the 6000 years most thought at that time.

Early Scientist proposed ideas about evolution E. Darwin – C. Darwin’s grandfather and an English doctor: more-complex forms developed from less-complex forms – C. Darwin expanded upon this idea 65 years later. Lamarck – A French naturalist: environmental change leads to use or disuse of a structure – He proposed the idea of inheritance of acquired traits - his explanations were flawed Example: He said a giraffe’s neck would grow longer the more they stretched to use it and that their offspring would have longer necks because of this. --- WRONG!

WRONG!

Theories of geologic change set the stage for Darwin’s theory. Georges Cuvier explained – catastrophism – natural disasters such as floods and volcanic eruptions caused massive amounts of species to become extinct and other species moved into an area after each catastrophic event.

Gradualism Proposed by James Hutton, a Scottish geologist – changes observed in landforms resulted from slow changes over a long period of time, a principle known as gradualism.

English geologist, Charles Lyell – expanded Hutton’s idea of gradualism into the theory of uniformitarianism. This idea replaced catastrophism as the accepted theory of geologic change.