The screenplay by Mark L. Smith and Iñárritu is based on Michael Punke's 2002 novel of the same name and partly on "Man in the Wilderness", starring Richard Harris and John Huston.
The screenplay by Mark L. Smith and Iñárritu is based in part on Michael Punke's 2002 novel of the same name. And, partly, on the 1971 film "Man in the Wilderness" starring Richard Harris and John Huston.