Folk taxonomy

Folk taxonomies are systems of categorization created by non-scientists in order to organize, name, and understand the natural world. Folk taxonomies frequently diverge on some points from the phylogeny established by the scientific study of taxonomy but they also tend to align with scientific classifications on other points: sometimes folk taxonomies lump together many biological species under a single name or place species from several different biological orders in the same group, sometimes there is one-to-one correspondence, and sometimes folk taxonomies differentiate where scientific taxonomies do not. Differentiation between types in folk taxonomies is determined by a wide variety of attributes, some of which may not be immediately obvious to outsiders; morphology and behavior are important but so are the cultural significance and practical utility of the species constituting each group.

Psychological roots

In a highly influential and oft cited chapter, Eleanor Rosch postulated two fundamental principles that govern the formation of "the categories found in a culture and coded by the language of that culture at a particular point in time." Rosch's first principle is that organisms, humans included, seek to gain as much information from the environment as possible while exhausting as few cognitive resources as possible. The second principle is that certain perceived attributes occur together more often than others. Categorization is made possible by the second principle and is made desirable by the first.