AP BIOLOGY

Detailed explanation-1: -Darwin had in natural selection an explanatory hypothesis to account for the adaptations of organisms that would allow him to design observations and experiments for testing the hypothesis’ validity.

Detailed explanation-2: -Evolution is only a theory. It is not a fact or a scientific law. Many people learned in elementary school that a theory falls in the middle of a hierarchy of certainty-above a mere hypothesis but below a law. Scientists do not use the terms that way, however.

Detailed explanation-3: -Evolution, in this context, is both a fact and a theory. It is an incontrovertible fact that organisms have changed, or evolved, during the history of life on Earth. And biologists have identified and investigated mechanisms that can explain the major patterns of change.

Detailed explanation-4: -Some types of evidence, such as fossils and similarities between related living organisms, were used by Darwin to develop his theory of natural selection, and are still used today. Others, such as DNA testing, were not available in Darwin’s time, but are used by scientists today to learn more about evolution.