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Unformatted text preview: Biology Notes Chapter 22 Darwin Introduces a Revolutionary Theory • Darwin introduced a revolutionary theory on November 24, 1859 with the publication of the book On the Origin of Species by Means of Natural Selection o He did not invent evolution, but rather provided an explaining mechanism and gave ample evidence • He made two major points in the book o First, he presented evidence that many species of organisms were decedents of ancestral species that were different o Second, he proposed a mechanism for evolution, called natural selection Natural Selection basic idea states that a population can change over generations if individuals that possess certain heritable traits leave more offspring than other individuals • Result is evolutionary adaption, accumulation of inherited characteristics • Evolution is a change over time in the genetic composition of a population The Darwinian Revolution challenged traditional views of a young Earth • Darwin’s views of life contrasted sharply with traditional beliefs that earth was only a few thousand years old • Previous views included Aristotle’s scala naturae theory, which stated that organisms were arranged on a ladder of increasing complexity • Carolus Linnaeus sought to classify life’s diversity “for God”—developed taxonomy, the branch of bio concerned with naming and classifying organisms o Although he did not intend to support Darwin, this system helped to play a role in arguments supporting evolution • The study of fossils also helped to lay the groundwork for Darwin’s ideas o Fossils are remains or traces of organisms from the past Usually found in sedimentary rocks, formed at the bottom of water bodies Higher up sediments are younger than lower sediments o Paleontology, the study of fossils, was developed by Cuvier The deeper the fossils, the more dissimilar they were from current organisms He observed that sometimes, species would disappear within strata • Came up with catastrophism, the boundaries between strata that had different species was a result of a disaster • Other scientist sought to explain these differences with Gradualism—the idea that profound change can take place through the cumulative effect of slow but continuous process o Hutton state that geologic features could be explained by this process, which would still be occurring • Charles Lyell incorporated Hutton’s thinking into uniformitarianism—which stated that the same geologic processes are operating today as in the past at the same rate • Lamarck came up with a theory of evolution with 2 concepts—the first was use and disuse, the idea that parts of the body that are more extensively used become larger and stronger; the second was of inheritance of acquired characteristics, which stated that an organism could pass these modifications to its offspring o Eg. Giraffe In The Origin of Species, Darwin proposed that species change through natural selection • Darwin’s initial steps of forming the basis of natural selection occurred when he...
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