When we think of scientists in Antiquity, names like Pliny the Elder and Ptolemy come to mind. Some may throw Hippocrates in the mix if they're in the know, but most everyone associates that name with medicine rather than biological studies.

Where does Galen fit in?

Galen, with his privileged background and a penchant for making people actively seek his death, is nowhere near as renowned or revered today as the man whom he claimed was the ultimate authority on medical science. Indeed, he's better known for healing emperors and gladiators than any discovery made in physiology.

Doesn't that make it odd, then, that his medical experiments and advances have done more to shape modern medicine than even the Father of Medicine himself?

Who is this Galen? What did he do? How could he have done so much yet be so little known? Superprof says it's time to investigate.

Galen: Early Life and Start in Medicine

Galen of Pergamum was born to a well-to-do family in 129AD. This son of Greek architect, Aelius Nicon, was born in territory controlled by the Roman Empire. Today, Pergamum lies in Turkey; it is now called Bergama.

Despite being born on Roman soil, spending most of his working life tending to prominent Roman citizens and dying in Rome, Galen retained the Greek citizenship awarded him through his father's nationality.

By all accounts, Galen benefited equally from both of his parents' temperaments.

Galen was far ahead of his time in dissecting animals to understand humans
Galen’s research left future biologists a laundry list of new information about human physiology whose most famous debunking was done by an English biologist. Source: Wikipedia Credit: Georg Paul Busch

In his work On the Passions and Errors of the Soul, he described his father as the kindest and least irascible father ever. By contrast, he likened his mother to a shrew, an ill-tempered beast who would often shriek at his father and bite her handmaids.

Years later, Galen, the medicine man, would suffer fits of temper so vicious that he alienated every ally, even as the most powerful Romans sought out his treatments and cures. We're getting a bit ahead of ourselves, here. Let's go back to his foundation years... 

Nicon the Architect was quite the learned man, excelling in mathematics, astronomy, philosophy and literature. In that sense, he was quite like Aristotle, who also pursued every avenue of intellectual inquiry. However, Aristotle also studied biology, dabbled as a zoologist, and investigated other areas of physical science.

Nicon charted his son's course early on, steering him towards a life of philosophy and perhaps politics. One night, he had what he thought was a prophetic dream. In this dream, he was visited by the Greek god of healing, Asclepius, who told him his son should study medicine. And, just like that, his carefully laid plans for his son's future were cast aside in favour of following that god's command.

At that time, Humourism was the prevailing medical theory. These humours - blood, phlegm, and yellow and black biles were thought to be all that the body consists of and, thus, the cause of all illness and pain. If these four solutions are in proper balance, the body is well.

Through his work, Galen would discover that humoural theory was the least factual of all knowledge about medicine.

Did you know that Hippocrates was an early follower of the Humourist theory? It was one of his few medical missteps.

Galen's Travels and Work

Galen started his studies in medicine in Pergamum, at the healing temple dedicated to the god his father had dreamt of. However, when his father died, leaving him independently wealthy at 19 years old, he decided to follow the advice of his medical hero, Hippocrates. He set out to travel the known world and learn what he could.

History places him in Smyrna (called Izmir today), Crete, Cyprus and Corinth. There, he learned about physiology, a bit about botany and other aspects of biology. He attended the medical school in Alexandria, at the time as renowned as the American Harvard University or the British University of Cambridge medical schools are today.

With his wanderlust satisfied and, presumably, in possession of all the medical and physiology knowledge available, he returned to Pergamum to become the physician to the Gladiators. He was also hired by the High Priest of Asia after a particularly stunning display of medical ability that involved eviscerating and subsequently performing surgery on an ape.

Doctors knew little about how the body worked in Galen's time
Biologists in Galen’s time knew little about the natural workings of the human body because dissection was forbidden. Photo credit: crackdog on Visualhunt / CC BY

When he was around 33 years old, he moved to Rome. There, he often got into conflict with his fellow physicians because of his brusque manner. He belittled their skills and berated them for being too conservative in their practice of medicine. Soon, fearing for his life in the backlash, he fled Rome.

He was brought back eight years later and instructed to accompany two generals to the German front, where Romans were at war but, in the end, was allowed to remain in Rome to tend to the remaining leader. While there, he wrote extensively about medicine, physiology, biology and natural, plant-based remedies.

Side note: while Galen combed the earth for new knowledge and medical techniques, Mendel stayed in his monastery, growing various species of peas. Just goes to show you don't have to be a world traveller to study evolution...

Galen's Particularities

Not much was known about the composition and workings of the human body because cutting one open had, for centuries, been banned by Rome. Galen found a way around that edict: he dissected animals.

Galen intuited that apes were similar to people in their anatomy. This idea led him to cut on live animals as well as dead ones. As horrible as that practice sounds, he learned a lot from his experiments. For one, he firmly established that blood rather than air flowed through veins.

Few people regard Galen as a biologist - at best, they might consider him a zoologist for all of the work he did on animals. We have to understand, though, that he dissected apes to understand how the human body worked, not because of any interest in how animals' bodies are structured.

Side note: he started his experiments with apes but later cut pigs open because those simian faces too closely resembled human ones.

Had Galen had the equipment to study DNA, cell structure or anything on the microbiology level, he probably would have. Despite his foul temper and terrible disposition, his was an avidly curious mind.

He discovered how the trachea functioned and outlined its design as well as a nearby anatomical structure, the larynx. He also discovered how lungs function... by inflating a set of lungs with a bellows. Throughout history, he remained the authority on anatomy... but only until the 16th Century

By then, the ban on human dissection was lifted. Plenty of scientists and medical men had no qualms cutting people open; they could (and did) refute much of what Galen got wrong.

His physiology studies were largely guided by philosophical thinkers such as Aristotle and that biologist's teacher, Plato. Naturally, his hero in medicine, Hippocrates, played a significant role but, for all of these influences, Galen made fantastic leaps of intuition, of which quite a few have been proven.

Indeed, Galen was a peculiar in his science and brutal in his research. But then, Charles Darwin, our most renowned naturalist and zoologist, had a few particularities of his own...

Galen gave us our knowledge of how lungs work
Galen gave the world its first full explanation of the lungs and how they work. Scientists today still draw upon the knowledge gained from his experiments. Photo credit: joshc on VisualHunt.com / CC BY-NC-SA

Galen's Legacy

Much of our understanding of human anatomy comes directly from Galen's work. His (gruesome) experiments brought about an evolution in understanding how the human body works; thanks to his work, we know:

  • the difference between venous and arterial blood
  • the circulatory system
  • the respiratory system
  • the nervous system - including the difference between sensory and motor nerves
  • the spinal cord
  • the vertebral column
  • the reproductive system

To be sure, he made mistakes along the way. He couldn't study human anatomy so some of his interpretations are decidedly not human - such as the uterus which, in his descriptions, resembles that of a dog's.

Would Galen have won the Nobel prize as a biologist, naturalist or even as a scientist if such recognition were given in those times? Probably not. For all that his work was ground-breaking, it was callous and unethical. By today's standards, he would likely be reviled for the work he did.

One remarkable aspect of Galen's work was that, even though every discovery he made was on non-human animals, he apparently never thought anything about the species he dissected. He only ever interpreted his findings through the lens of the human body. Oh, what a zoologist he could have been!

After his death in 210AD, his many written works continued to be widely circulated. The University of Alexandria even taught from his books.

His biggest initial impact was in the Arab world. His books were translated from Greek and widely distributed, making Galen's discoveries the foundation of medical practice throughout eastern Asia.

By contrast, his work fell into obscurity in the western hemisphere until around the 12th Century, when Arab texts were translated into Latin. They then became the foundation of medical education in medieval universities.

As a scientist trained in philosophy, Galen was fascinated by the Empiricist/Rationalist debate. He apparently aligned himself with the empirical side, albeit cautiously. His later work reflects that judgment, a feature that university professors in the Middle Ages emphasised - along with his clinical and diagnostic methods.

And so, for centuries, the long-dead Galen remained the final authority on human anatomy and medicine... until the English physician, William Harvey correctly diagrammed how blood flows through the body - one of Galen's many mistakes. But who could blame him for making errors?

His work underpins all of our medical practices but Galen is at risk of fading into obscurity, as so many other biologists and scientists are. Isn't it time to rediscover famous biologists and explore their history?

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A vagabond traveler whose first love is the written word, I advocate for continuous learning, cycling, and the joy only a beloved pet can bring. There is plenty else I am passionate about, but those three should do it, for now.