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
Baboon Guinea baboon is and weighs only , while the largest chacma baboon can be and weigh . Five species of "Papio" are commonly recognized, although there is some disagreement about whether they are really full species or subspecies. They are "P. ursinus" (chacma baboon, found in southern Africa), "P. papio" (western, red, or Guinea baboon, found in the far western Africa), "P. hamadryas" (hamadryas baboon, found in the Horn of Africa and southwestern Arabia), "P. anubis" (olive baboon, found in the north-central African savanna) and "P. cynocephalus" (yellow baboon, found in south-central and eastern Africa). Many authors distinguish "P. hamadryas"