Ancient Rome’s most notorious doctor - Ramon Glazov
 In the middle of the 16th century,
  a talented young anatomist named Andreas
 Vesalius made a shocking discovery:
  the most famous human anatomy texts in 
 the world were wrong.
  They not only failed to account for many
 details of the human body,
  they also described the organs of apes
 and other mammals.
  While Vesalius knew he was right,
  announcing these errors would mean
 challenging Galen of Pergamon–
  the most renowned physician 
 in medical history.
  But who was this towering figure?
  And why did doctors working more than
 1,300 years later so revere and fear him?
  Born in 129 CE,
  Galen left home as a teen to scour the
 Mediterranean for medical wisdom.
  He returned home a gifted surgeon with a
 passion for anatomy
  and a penchant for showmanship.
  He gleefully entered public anatomy 
 contests,
  eager to show up his fellow physicians.
  In one demonstration,
  he caused a pig to lose its voice by tying
 off one of its nerves.
  In another, he disemboweled a monkey and
 challenged his colleagues to repair it.
  When they couldn’t, he did.
  These grizzly feats won him a position as 
 surgeon to the city’s gladiators.
  Eventually, he would leave the arena 
 to become the personal physician
  to four Roman Emperors.
  While his peers debated symptoms and 
 their origins,
  Galen obsessively studied anatomy.
  He was convinced that each organ had a
 specific function.
  Since the Roman government largely 
 prohibited working with human cadavers,
  Galen conducted countless dissections 
 of animals instead.
  Even with this constraint,
  his exhaustive investigations yielded 
 some remarkably accurate conclusions.
  One of Galen’s most important 
 contributions
  was the insight that the brain,
 not the heart, controlled the body.
  He confirmed this theory by opening the
 cranium of a living cow.
  By applying pressure to different 
 parts of the brain,
  he could link various regions 
 to specific functions.
  Other experiments allowed him to 
 distinguish sensory from motor nerves,
  establish that urine was 
 made in the kidneys,
  and deduce that respiration was 
 controlled by muscles and nerves.
  But these wild experiments also produced 
 extraordinary misconceptions.
  Galen never realized that blood cycles
 continuously throughout the body.
  Instead, he believed the liver constantly
 produces an endless supply of blood,
  which gets entirely depleted on its 
 one-way trip to the organs.
  Galen is also credited with solidifying 
 the popular theory of the Four Humours.
  Introduced by Hippocrates 
 centuries earlier,
  this misguided hypothesis attributed most
 medical problems
  to an imbalance in four bodily fluids 
 called humours.
  To correct the balance of these fluids, 
 doctors employed dangerous treatments
  like bloodletting and purging.
  Informed by his poor understanding 
 of the circulatory system,
  Galen was a strong proponent 
 of these treatments,
  despite their sometimes lethal 
 consequences.
  Unfortunately, Galen’s ego 
 drove him to believe that
  all his discoveries were 
 of the utmost importance.
  He penned treatises on everything from
 anatomy to nutrition to bedside manner,
  meticulously cataloguing his writings 
 to ensure their preservation.
  Over the next 13 centuries,
  Galen’s prolific collection dominated 
 all other schools of medical thought.
  His texts became the standard works 
 taught to new generations of doctors,
  who in turn, wrote new essays extolling 
 Galen’s ideas.
  Even doctors who actually dissected 
 human cadavers
  would bafflingly repeat Galen’s mistakes,
  despite seeing clear evidence 
 to the contrary.
  Meanwhile, the few practitioners bold 
 enough to offer conflicting opinions
  were either ignored or ridiculed.
  For 1,300 years, Galen’s legacy 
 remained untouchable–
  until renaissance anatomist Vesalius 
 spoke out against him.
  As a prominent scientist and lecturer,
  his authority influenced many young 
 doctors of his time.
  But even then, it took another
 hundred years
  for an accurate description 
 of blood flow to emerge,
  and two hundred more for the theory 
 of the Four Humours to fade.
  Hopefully, today we can reap the benefits
 of Galen’s experiments
  without attributing equal credence 
 to his less accurate ideas.
  But perhaps just as valuable
  is the reminder that science is an 
 ever-evolving process,
  which should always place 
 evidence above ego.