"Musilanguage" is a term coined by Steven Brown to describe his hypothesis of the ancestral human traits that evolved into language and musical abilities. It is both a model of musical and linguistic evolution and a term coined to describe a certain stage in that evolution. Brown argues that both music and human language have origins in a "musilanguage" stage of evolution and that the structural features shared by music and language are not the results of mere chance parallelism, nor are they a function of one system emerging from the other. This model argues that "music emphasizes sound as emotive meaning and language emphasizes sound as referential meaning." The musilanguage model is a structural model of music evolution, meaning that it views music's acoustic properties as effects of homologous precursor functions. This can be contrasted with functional models of music evolution, which view music's innate physical properties to be determined by its adaptive roles.