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Evolution, theory of

DOI: 10.4324/9780415249126-Q032-1
Version: v1,  Published online: 1998
Retrieved July 16, 2024, from

Article Summary

The biological theory of evolution advances the view that the variety and forms of life on earth are the result of descent with modification from the earliest forms of life. Evolutionary theory does not attempt to explain the origin of life itself, that is, how the earliest forms of life came to exist, nor does it apply to the history of changes of the non-biological parts of the universe, which are also often described as ’evolutionary’. The mechanisms of natural selection, mutation and speciation are used in evolutionary theory to explain the relations and characteristics of all life forms. Modern evolutionary theory explains a wide range of natural phenomena, including the deep resemblances among organisms, the diversity of life forms, organisms’ possession of vestigial organs and the good fit or ’adaptedness’ between organisms and their environment.

Often summarized as ’survival of the fittest’, the mechanism of natural selection actually includes several distinct processes. There must be variation in traits among the members of a population; these traits must be passed on from parents to offspring; and the different traits must confer differential advantage for reproducing successfully in that environment. Because evidence for each of these processes can be gathered independently of the evolutionary claim, natural selection scenarios are robustly testable. When a trait in a population has arisen because it was directly selected in this fashion, it is called an adaptation.

Genetic mutation is the originating source of variation, and selection processes shape that variation into adaptive forms; random genetic drift and various levels and forms of selection dynamic developed by geneticists have been integrated into a general theory of evolutionary change that encompasses natural selection and genetic mutation as complementary processes. Detailed ecological studies are used to provide evidence for selection scenarios involving the evolution of species in the wild.

Evolutionary theory is supported by an unusually wide range of scientific evidence, gaining its support from fields as diverse as geology, embryology, molecular genetics, palaeontology, climatology and functional morphology. Because of tensions between an evolutionary view of homo sapiens and some religious beliefs, evolutionary theory has remained controversial in the public sphere far longer than no less well-supported scientific theories from other sciences.

Citing this article:
Lloyd, Elisabeth A.. Evolution, theory of, 1998, doi:10.4324/9780415249126-Q032-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2024 Routledge.

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