It has been argued that properties of the visual-gestural modality impose a homogenizing effect on sign languages, leading to less structural variation in sign

Darwin's theory of evolution by natural selection was based on the observation that there is variation between individuals within the same species. This fundame

Geographic Variation, Speciation and Clines explores the origins and development of geographic variation, divergence, and speciation. In particular it is concer

The problem of finding minimal surfaces, i. e. of finding the surface of least area among those bounded by a given curve, was one of the first considered after