, where the first half of the film was shot The film was loosely inspired by the novels
Lord of the Flies by
William Golding and
Heart of Darkness by
Joseph Conrad. Filmic influences included the Soviet film
Come and See and the French film
Beau Travail. While "
monos", the title as well as the code name of the main squad in the film, superficially means "monkeys" in Spanish, it signifies the prefix
mono- of Greek origin meaning "alone" or "one" according to Landes. More than 800 children across Colombia were considered for the main roles of child soldiers. First, 20 to 30 were chosen to participate in a weeks-long camp in mountains, where they received acting training from Argentine actress
Inés Efron in the morning, and military training from Wilson Salazar, who plays the Messenger, in the afternoon, and the final eight were cast among them. Salazar was a
FARC soldier from age 11 to 24, and Landes found him at one of the reinsertion programmes Landes visited for research. Landes first hired Salazar as a consultant before casting him as the Messenger. The role of Rambo, played by Buenaventura, who goes by Matt, was originally written to be a boy, but Landes made the character's gender ambiguous during the casting process.
Monos marked the first film appearances of the main actors aside from Arias and Nicholson. Quintero and Castrillón had acting experience in theatre. Buenaventura and Giraldo have continued acting in film since
Monos. The mountain scenes were shot in
Chingaza National Natural Park, four hours outside of
Bogotá and more than above sea level. The jungle scenes were shot around the
Samaná Norte River in
Antioquia Department, five hours from
Medellín. Underwater scenes were shot with buoyancy equipment attached to the actors, with the kayak team helping ensure safety. Prominent underwater cinematographer Peter Zuccarini joined the crew for three to four days. Levi first made short compositions involving whistles, made by Levi blowing into a glass bottle,
timpani, and a synthesizer sound, around which further compositions were built. Different sounds were assigned to represent various characters: a shrill bottle whistle became the "authority whistle", evoking the presence of the Organization; a bird-like whistle represented the bond among the child soldiers; and timpani accompanied with the authority whistle represented "the shadowy force that tries to control the group from a distance". The score is used sparingly throughout the film, taking up only 22 minutes. ==Release==