Untamed Heart agent, MGM had greenlighted the project. Originally, the film was titled "The Baboon Heart" in honor of an infant named Baby Fae (born 14 October 1984) who received a cross-species heart transplant from a baboon to fix a congenital heart defect. Initially, Bill had not considered Christian Slater for the role of Adam, “but then it was just the obvious choice." For the role of Caroline, Bill remembered auditioning Marisa Tomei for his earlier film, "Five Corners". While she had been too young for that role, after her success with "My Cousin Vinny" he felt she was right for the
Chacma baboon wild. This has reduced baboon numbers and disrupted their social structure. Due to hybridization between different baboon ("Papio") populations across Africa, authors have occasionally grouped the entire radiation as a single species, the hamadryas baboon, "Papio hamadryas". Arbitrary boundaries were then used to separate the populations into subspecies. Other authors considered the chacma baboon a subspecies of the yellow baboon, "Papio cynocephalus", though it is now recognised as a separate species, "Papio ursinus". The chacma baboon has two or three subspecies, depending on which classification is followed. Grubb et al. (2003) listed two subspecies, while Groves (2005) in Mammal Species