Spandrel
From Free net encyclopedia
A spandrel is originally a term from Architecture, but has more recently been given an analogous meaning in Evolutionary biology. Architecturally, a spandrel (less often spandril or splaundrel) is the space between two arches or between an arch and a rectangular enclosure. In evolutionary biology, a spandrel is a phenotypic characteristic that evolved as a side effect of a true adaptation.
The Soviet Union produced a missile that was called the AT-5 Spandrel by NATO.
Architecture
There are four or five accepted and cognate meanings of spandrel in architectural and art history, all relating to the space between a curved figure and a rectangular boundary - such as the space between the curve of an arch and a rectilinear bounding moulding, or the wallspace bounded by adjacent arches in an arcade and the stringcourse or moulding above them, or the space between the central medallion of a carpet and its rectangular corners, or the space between the circular face of a clock and the corners of the square revealed by its hood.
The spandrels over doorways in Perpendicular work are generally richly decorated. At Magdalen College, Oxford, is one which is perforated, and has a most beautiful effect. The spandril of doors is sometimes ornamented in the Decorated period, but seldom forms part of the composition of the doorway itself, being generally over the label.
Because arches are commonly used in bridge construction, spandrels may also appear in those structures. Most arch spans up until the advent of steel and reinforced concrete in the 19th and 20th centuries were solid-spandrel, meaning that the areas between arches were completely filled in—usually with stone. Open-spandrel bridges later became fairly common, where thin ribs were used to connect the upper deck to the bridge arches, resulting in a significant savings in material, weight, and therefore cost. Reinforced-concrete open-spandrel bridges were fairly common for crossing large distances in the 1920s and 1930s.
Early domes also created spandrels, inherent in the limits of medieval engineering. In order to support a circular dome, the dome had to sit on a square structure supported by (at least) four pillars; this practise creates spandrels between the outer edge of the dome and the square supporting structure that can be seen in many such domes.
See also: Cathedral architecture
Biology
[[Category:{{{1|}}} articles with sections needing expansion]]
Another usage of the word spandrel was popularized by Stephen Jay Gould and Richard Lewontin in the paper "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme". In the context of evolution, a spandrel is a metaphor for characteristics that are or were originally side effects and not true adaptations to the environment. They are analogous to misbugs in hacker jargon.
This metaphorical meaning works no matter which kind of architectural spandrel is referred to: the spandrel is the un-designed gap between other features, which is then often exploited for a use of its own.
References
- Stephen Jay Gould and Richard C. Lewontin. "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme." Proc. Roy. Soc. London B 205 (1979) pp. 581-598
- Gould SJ (2002) The structure of evolutionary theory. Belknap Press of Harvard University Press, Cambridge, Mass.
- Phillip Stevens Thurtle. "The G Files: Linking 'The Selfish Gene' And 'The Thinking Reed'"
This article incorporates text from the Encyclopædia Britannica Eleventh Edition{{#if:{{{article|}}}| article {{#if:{{{url|}}}|[{{{url|}}}}} "{{{article}}}"{{#if:{{{url|}}}|]}}{{#if:{{{author|}}}| by {{{author}}}}}}}, a publication now in the public domain.nl:zwik