Short answers, pulled from the story.
Galen was a Roman and Greek physician, surgeon, and philosopher born in September 129 in Pergamon. He is considered one of the most accomplished medical researchers of antiquity, and his views dominated Western medical science for more than 1,300 years. He served as personal physician to several Roman emperors.
Galen was born in September 129 in the ancient city of Pergamon, present-day Bergama, Turkey. His father was Aelius Nicon, a wealthy Greek architect with scholarly interests in philosophy, mathematics, logic, and astronomy.
Roman law forbade the dissection of human cadavers in Galen's time, so he relied on apes and pigs. He switched from Barbary apes to pigs partly because the apes' vivid facial expressions risked drawing prosecution, reasoning that animal anatomy closely mirrored human anatomy.
The Antonine Plague was a great pestilence, most likely smallpox, that broke out in the Roman world and was also known as the Plague of Galen. It had a mortality rate of 7 to 10 percent, and the outbreak of 165 to 168 would have caused roughly 3.5 to 5 million deaths. Galen was present in Rome when it struck in 166 and described its symptoms and treatment.
Galen's theory of the circulatory system stood until around 1242, when Ibn al-Nafis reported his discovery of pulmonary circulation. His anatomical reports remained uncontested until 1543, when Andreas Vesalius published De humani corporis fabrica based on human cadaver dissections.
Galen may have written as many as 500 treatises amounting to some 10 million words, with twenty scribes reportedly taking down his words. His surviving works run to roughly 3 million words, thought to represent less than a third of his complete writings, and they make up nearly half of all extant literature from ancient Greece.
Galen's death date is debated. The Suda lexicon places it around the year 199 at age 70, while Arabic sources say he died in Sicily at age 87, around the year 216, after 17 years studying medicine and 70 practicing it.