John Chambers worked in a military hospital as a creator of prosthetic noses, chins and other body parts for disfigured patients, but eventually decided that he'd had enough tragedy and moved to Hollywood to become a highly sought-after makeup artist. His genius was on display in "Planet of the Apes" for which he won the first Oscar ever given for makeup.
In creating the simian inhabitants of a future dystopia, Chambers made individual molds of each of the actors and then used them to make foam masks that were carefully glued to their faces with spirit gum. That became a base for him to apply makeup and attack apelike foreheads noses, ears and other features make of latex, fake teeth and fur wigs. The trickiest part reportedly was modifying the mouths so that the actors could speak naturally, without sounding like voices coming from inside of a cavern [sources: Hollywood.com, Russo et al.].