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Homology: An Architectural Inheritance

Although we typically think of homologies in terms of anatomical structures, this is only one level at which homologies occur. In fact, even behaviors can be homologous. The architectural habit of the lovesick bowerbird is a case in point. A male bowerbird woos his chosen one by building a fanciful "bower" that serves as a stage for his elaborate courtship ritual. A successful performance will entice a female to mate with him. Each species of bowerbird builds a slightly different bower and puts on a slightly different performance. However, all bowerbird species have some version of this "performance art" mating ritual — a behavior quirk inherited from a common ancestor who also used this sort of mating ritual. Thus, this behavior pattern is a homology and supports the close evolutionary relationship among bowerbird species.

Satin bowerbird MacGregor's bowerbird
Different species of bowerbird construct elaborate bowers and decorate them with different colors in order to woo females. The Satin bowerbird (left) builds a channel between upright sticks, and decorates with bright blue objects, while the MacGregor's Bowerbird (right) builds a tall tower of sticks and decorates with bits of charcoal.

Satin bowerbird photo courtesy of Graeme Guy; MacGregor's bowerbird photo courtesy of Stephen and Melinda Pruett-Jones.

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