spandrel

Coordinate term: pendentive

Due to the fact that the walls are joined by floors and spandrels, a coupling effect is produced. Depending on the extent of the spandrels, this coupling effect will be bigger or smaller.

Another type of theory emphasises the sometimes accidental nature of evolution. A spandrel is a structure arising as a by-product of some other architectural configuration. In evolutionary terms, a spandrel is some trait of an organism which emerges not through direct adaptionist or exaptationist means, but rather as a side effect of some other evolutionary development.