analogy

analogy, in biology, the similarities in function, but differences in evolutionary origin, of body structures in different organisms. For example, the wing of a bird is analogous to the wing of an insect, since both are used for flight. However, there is no common ancestral origin in the evolution of these structures: While the wings of birds are modified skeletal forelimbs, insect wings are extensions of the body wall. Although insects and birds do have a very remote common ancestry (more than 600 million years ago), the wings of the two groups evolved after their ancestries had separated. See also homology.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.

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