From the 2nd Century AD to the end of the Middle Ages, it was an accepted tenet that monkeys had the inner workings quite like those of man. This was the anatomical point of departure established by the 2nd-Century Greek physician Claudius Galenus – commonly referred to as Galen – who at the time was the authority on all things medical in Western Europe and Byzantium.

Yet due to religious, legal and cultural taboos, he had never systematically dissected human bodies. Instead, his writings and dissections of monkeys, specifically Barbary and rhesus macaques, guided the development and practice of medicine for around 1,400 years. And then something ground-breaking happened. A scientific revolution burst through the self-imposed limits of ancient knowledge.