"
In such isolated high country, away from 
opprobrious comment and watchful eyes, I thought it would be plausible for the characters to get 
into a sexual situation.  That's noth
ing new or 
out of the ordinary; livestock workers have a blunt and full understand
ing of the sexual behaviors of man and beast." 
-- Annie Proulx, Brokeback Mountain: From Story to Screenplay, "Getting Movied"