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Chapter 15. Theory of Evolution Section 1 History of Evolutionary Thought. Charles Darwin. 1809 - 1882 Darwin’s theories became the basis for the way evolution is explained today. . Ideas of Darwin’s time:. 18 th century- all species are permanent and unchanging
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Chapter 15 Theory of Evolution Section 1 History of Evolutionary Thought
Charles Darwin 1809 - 1882 Darwin’s theories became the basis for the way evolution is explained today.
Ideas of Darwin’s time: • 18th century- all species are permanent and unchanging • Earth is thousands (not billions) of years old
Darwin and the Galapagos Islands • Spent 5 years traveling to study animals; noted for excursion to the Galapagos Islands • He noticed: • Groups of animals varied from island to island (tortoises, for example) • Also noticed that there were similarities and differences between animals in other parts of the world
His findings led him to believe that organisms change over time… • Evolution- the development of new types of organisms from preexisting types of organisms over time
Geology ideas of the time… • Scientists begin to study rock strata- layers of rock • Inferred that the rock layers on the bottom are older than the rock layers on the top- the principle of superposition
Georges Cuvier • Studied fossils in rock layers to determine: 1) organisms from the past are different than organisms living today 2) some organisms have become extinct Explained this with the idea of catastrophism
Catastrophism • The idea that sudden geologic events caused the extinction of large groups of organisms
Charles LyellUniformitarianism • Believed that geologic processes that have changed the earth in the past still change the earth today • Ex. erosion
If the earth could change over time… • …why couldn’t living things? • Cuvier and Lyell’s ideas supported Darwin’s theory about organisms changing over time.
Jean Baptiste Lamarck * inheritance of acquired characteristics- Individuals could acquire traits during their lifetime and then pass those traits on to their offspring 1744-1828
Lamarck’s theory explained how organisms changed BUT that they changed in a lifetime. • He also thought simple organisms could arise from nonliving matter. • Darwin once accepted Lamarck’s theory but changed his mind
Inheritance of Acquired Characteristics • If a person developed muscles during their lifetime, their child would be born with muscles
One giraffe stretches its neck more to reach leaves. Over time, the neck becomes longer and then the babies are born with longer necks as well. Theory of Use and Disuse