stylistic:style_transfer, structural:scholar_edition, quality:corruption
Evolution-progression model

Human language is used for self-expression; however, expression displays different stages. The consciousness of self and feelings represents the stage immediately prior to the external, phonetic expression of feelings in the form of sound, i.e., language. Intelligent animals such as dolphins, Eurasian magpies, and chimpanzees live in communities, wherein they assign themselves roles for group survival and show emotions such as sympathy. When such animals view their reflection (mirror test), they recognise themselves and exhibit self-consciousness. Notably, humans evolved in a quite different environment than that of these animals. Human survival became easier with the development of tools, shelter, and fire, thus facilitating further advancement of social interaction, self-expression, and tool-making, as for hunting and gathering. The increasing brain size allowed advanced provisioning and tools and the technological advances during the Palaeolithic era that built upon the previous evolutionary innovations of bipedalism and hand versatility allowed the development of human language.