Baby Fae body began generating isohaemagglutinins, but a suitable donor could not be found in time. Prior to the procedure, no infant heart transplant—even with human hearts—had been successfully performed due to a lack of infant human hearts. To address this issue, Bailey had become a pioneer in the research of cross-species heart transplants, which had included "more than 150 transplants in sheep, goats, and baboons". Multiple surgeons had previously experimented with baboon heart implants, leading some to speculate even that baboons could be farmed in the future for such purposes. When asked why he had picked a baboon over a primate
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