text: Migrationism, the spread of cultural ideas by either gradual or sudden population movements
  Culture circles diffusionism (Kulturkreise)—the theory that cultures originated from a small number of cultures
  "Kulturkugel" (a German compound meaning "culture bullet", coined by J. P. Mallory), a mechanism suggested by Mallory to model the scale of invasion vs. gradual migration vs. diffusion. According to this model, local continuity of material culture and social organization is stronger than linguistic continuity, so that cultural contact or limited migration regularly leads to linguistic changes without affecting material culture or social organization.
  Hyperdiffusionism—the theory that all cultures originated from one culture
  A concept that has often been mentioned in this regard, which may be framed in the evolutionary diffusionism model, is that of "an idea whose time has come"—whereby a new cultural item appears almost simultaneously and independently in several widely separated places, after certain prerequisite items have diffused across the respective communities. This concept was invoked with regard to the independent development of calculus by Newton and Leibnitz, and the inventions of the airplane and of the electronic computer.
  Hyperdiffusionism
  Hyperdiffusionists deny that parallel evolution or independent invention took place to any great extent throughout history; they claim that all major inventions and all cultures can be traced back to a single culture.