spandrels of San Marco An analogy used, in a classic paper by Stephen Jay Gould and Richard Lewontin, to indicate how nonadaptive characters may arise in evolution. Spandrels are the spaces left between the tops of neighbouring arches in churches (in this case, St Mark's cathedral, in Venice); these spaces, not related to the functional architecture, are free to be decorated in a non-functional fashion.

spandrels of San Marco An analogy used, in a classic paper by Stephen Jay Gould and Richard Lewontin, to indicate how non-adaptive characters may arise in evolution. Spandrels are the spaces left between the tops of neighbouring arches in churches (in this case, St Mark's cathedral, Venice); these spaces, not related to the functional architecture, are free to be decorated in a non-functional fashion.