Footnote 40:

The Greek taboo against opening the human body, briefly suspended in Alexandria under Ptolemaic influence during the early third century BC, prevented Galen from directly investigating most internal features of human anatomy. As the closest possible substitute, he dissected and vivisected Barbary apes (Macaca silvanus) and possibly Rhesus monkeys (Macaca mulatta). See Von Staden 1989, 138ff. and Galen De anatom. admin. 1.2ff. (TLG 2.219.8ff.) “Of all living things the ape is likest man in viscera, muscles, arteries, veins and nerves, as in the form of the bones.”