CW Detroit Supernatural Episode Gallery: Survival Of The Fittest May 15, 2012 / 5:22 PM EDT / CBS News Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest Survival of the Fittest