ations (#5.06)_ (qv),  in which the character of Worf confirms that something did happen to  make the Klingons appear human, but he refuses to elaborate. In the  final season (season #4) of the fifth "Star Trek" series  _"Enterprise" (2001)_ (qv) an episode dealt with the exact nature of  why some Klingons (that would be the Klingons from the original  series) did not have the "knotted" forehead that visually  characterized all Klingons portrayed starting with  _Star Trek: The Motion Picture (1979)_ (qv). The premise was that a  group of Klingons on a Klingon