Unformatted text preview: derived. All life on earth today is thought to be descended from a single common ancestor. The Origin That evolution occurs over vast periods of time, and that evolution involves the extinction of species that do not produce competent viable offspring. A character is a genetic trait, such as hair. A character state includes all the biologically possible variances for that character (blonde, brown haired, red-headed). Derived character states. If the ancestral state were non-opposing thumbs, then opposable toes on the feet would have had to evolve independently in gibbons, gorillas, chimps and orangutans. The principle of parsimony requires that we assume the fewest numbers of evolutionary changes. If we do so, we find that humans have to have evolved non-opposable toes independently....
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- Spring '08
- Evolution, Trigraph, ich th er, hy po th, ch ara ct, ara ct er, evo lu tio