C HAPTER 15-1, T HE H ISTORY OF R EVOLUTIONARY T HOUGHT

V OCABULARY Evolution- A heritable change in the characteristics within a population from one generation to the next : the development of new types of organisms from preexisting types of organisms over time. Strata- Layers of rock. Natural Selection- The process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do : a theory to explain the mechanism of evolution. Adaptation- The process of becoming adapted to an environment : an anatomical, physiological, or behavioral trait that improves an organism’s ability to survive and reproduce. Fitness- In evolutionary theory, a measure of an individual’s hereditary contribution to the next generation.

D ARWIN ’ S T IME Charles Darwin ( ) visited the Galapagos Islands and was curious about how evolution changed the animals on each island. Began theory which other scientists failed to prove previously about evolution. Before Darwin, people thought the Earth was only thousands of years old and that animals were unchanging.

G EOLOGY (C UVIER AND L YELL ) Georges Cuvier ( ) studied the fossils of organisms in the strata by reconstructing them. The older the strata layer, the more different the organism from present-day organisms. Catastrophism: sudden geologic catastrophes caused the extinction of large groups of organisms in the past. Charles Lyell ( ), an English scientist Uniformitarianism: Lyell’s idea that the Earth’s geologic processes from the past work in the same way today.

L AMARCK ’ S I DEAS Jean Baptiste Lamarck ( ) had theories of evolution. Living organisms arose from nonliving matter. Simple organisms evolve into complicated organisms. Inheritance of acquired characteristics: individuals could acquire traits during their lifetimes as a result of experience or behavior, then could pass those traits onto offspring.

Inheritance of Acquired Characteristics Offspring

D ESCENT WITH M ODIFICATION Darwin and Alfred Russel Wallace ( ) created a new theory of “descent with modification”. Every species descended from a preexisting one and changes over time.

N ATURAL S ELECTION

F ITNESS An organism has a high fitness (in evolutionary terms) if it reproduces more successfully than other individuals. AB