Biology  5/e   Raven/Johnson
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Darwin's theory of evolution by natural selection: In 1859, Charles Darwin published a book explaining his theory of how and why species change over time. He recognized that some members of a population were better adapted to their environments than were other individuals in the population. The better adapted ones were more likely to survive and reproduce (and pass on their beneficial traits to their offspring) than were the less adapted members. Nature selected who reproduced, and because of this natural selection and differential reproduction the population gradually changed over time or in other words, it evolved. As generations passed, the population became better and better adapted to its environment.

DNA: DNA is the genetic material. It is the hereditary information that is passed on from parent to offspring. The sequence of nucleotides in an organism's DNA determines what that organism will be like, determines all of its traits. Natural selection acts on an organism's phenotype, but that phenotype is determined by the DNA and environment acting in concert. Without DNA and heritable traits, evolution could not occur.

Creationism: There is abundant and diverse evidence that evolution has occurred in the past and is continuing to occur today. Evolution is the best scientific theory to explain the origin of species on this planet. There are other explanations such as religious explanations, for the origin of species, but they are not scientific since they are not supported by empirical observations and do not produce testable hypotheses. Scientific creationism, despite its name, is one of the nonscientific explanations of how species arose on earth. Creationists believe in a literal interpretation of the Bible, with each species being individually and divinely created in their present form. Such an explanation is outside the realm of science.

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