Aristotle believed that all living forms could be arranged on a ladder of increasing complexity (scala naturae) with perfect, permanent species on every rung.The Greek philosopher Aristotle (384–322 B.C.E.) opposed any concept of evolution and viewed species as fixed and unchanging.The Origin of Species challenged a worldview that had been long accepted.Darwin’s view of life contrasted with the traditional view of an Earth that was a few thousand years old, populated by life forms that were created at the beginning and had remained fundamentally unchanged.Western culture resisted evolutionary views of life. Evolutionary perspectives continue to transform medicine, agriculture, biotechnology, and conservation biology.Ĭoncept 22.1 The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species.Evolution is such a fundamental concept that its study is relevant to biology at every level, from molecules to ecosystems.Evolution also refers to the gradual appearance of all biological diversity.In modern terms, we can define evolution as a change over time in the genetic composition of a population.Eventually, a population may accumulate enough change that it constitutes a new species.
Natural selection results in evolutionary adaptation, an accumulation of inherited characteristics that increase the ability of an organism to survive and reproduce in its environment.The basic idea of natural selection is that a population can change over time if individuals that possess certain heritable traits leave more offspring than other individuals.Natural selection provided a mechanism for this evolutionary change.Today’s organisms descended from ancestral species that were different from modern species.Darwin made two major points in The Origin of Species:.Darwin’s book drew a cohesive picture of life by connecting what had once seemed a bewildering array of unrelated facts.On November 24, 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection.Overview: Darwin Introduces a Revolutionary Theory Chapter 22 Descent with Modification: Darwinian View of Life