The Fathers of Modern Anatomy: The First Anatomists

The sheer volume of information that anatomy students are required to digest, dissect, commit to memory, and then reconquer in live clinical settings is daunting, to say the least. But this knowledge is the golden insight that mystified countless scholars for centuries, many of whom spent their lives contemplating their physicality in a metaphysical crisis.

Human anatomy, the branch of biology that focuses on understanding the body’s structural makeup, is the foundation of medicine.

The collective understanding in this field surged in the last three centuries as Renaissance artists and anatomists came together to fuel an interdisciplinary interaction that led to a revolution in science and medical education.

This collaboration led to the development of highly detailed, three-dimensional wax anatomical models that could be studied well beyond the onset of decay during cadaver dissections. Ultimately, this learning tool empowered scientists with the knowledge necessary to design the landmark interventions and treatments that now routinely stave off death and disease by decades.

However, for most of human history, scientists were not allowed to study the inside of the human body. Since human dissections were strictly forbidden, early anatomists would spend their days peering into wounds, thinking deeply about the structures that lie far underneath, and making inferences, many of which were massive misinterpretations that went unchallenged for centuries.

When human dissections were permitted during the early modern period, the entire field was transformed and reborn, as anatomists could finally examine the entire body and dispense with the older misconceptions.

The history of anatomy is rich with interesting people and intriguing stories. Below are three individuals who are arguably the most influential anatomists in human history. Sharing a keen eye and tremendous dedication, each of them revolutionized what human beings knew about their composition for centuries.

Herophilus [335-280 BC] – The Father of Anatomy

Herophilus, born in 335 B.C., is an ancient Greek physician with a controversial reputation in history for having dissected at least 600 live prisoners.

His home in Alexandria, Egypt, was one of the few places that allowed dissections for a 40-year period, during which Herophilus made a series of groundbreaking discoveries. He was the first person to perform systematic dissections of the human body and established himself as the Father of Anatomy.

During his time, conventional medicine propagated Hippocrates’ Theory of the Four Humors, which states that the body is composed of four substances (black bile, yellow bile, blood, and phlegm), each of which must coexist in a perfect balance for good health.

Without dissections to prove otherwise, many individuals supported Hippocrates’ theory and even came to believe that veins carried air, water, and blood.

While Herophilus shared similar medical beliefs, arguing that pneuma—a medium for neural transmission—flowed through arteries alongside blood, he discovered through his dissections that veins contained only blood, serving as one of the first in history to challenge this concept.

Still, he built on Hippocrates’ theory by adding that diseases were products of the four humors, which impeded the pneuma from reaching the brain.

Herophilus also battled the Aristotelian concept that the brain was a “cooling agent” for the heart, suggesting instead that the brain was the “seat of the intellect” and the human soul.

Even though he lived well before the common era, Herophilus recognized that damage to the motor nerves could induce paralysis, was the first person to distinguish the cerebrum and cerebellum, described the optic and oculomotor nerve for vision, and differentiated between nerves, arteries, and veins, being the first to point out that arteries had thicker walls than veins.

In addition to discovering the different sections and layers of the eye, Herophilus is credited with helping midwives and other doctors gain a more comprehensive understanding of pregnancy as a result of his contributions to the understanding of the female reproductive system.

An advocate for exercise and a healthy diet, he said that “when health is absent, wisdom cannot reveal itself, art cannot become manifest, strength cannot be exerted, wealth is useless, and reason is powerless.”

After Herophilus’ time, human dissections were banned for an 1800-year hiatus, setting the stage for flawed ideas to be nurtured for generations on end.

Galen [129 AD – 210 AD] – An Unchallenged Authority

Galen, a renowned surgeon and philosopher of the Roman Empire, was a pioneering anatomist deeply influenced by Plato, Aristotle, and Hippocrates. He revered medical knowledge and devoted his life to treating patients and deciphering the anatomy of the human body.

Unfortunately, Roman law prohibited human dissections, and Galen was forced to resort to other means to understand the human body; this predicament cost the scientific community for 1,400 years.

Galen spent his early life studying at Pergamon, Smyrna, and eventually, Alexandria, the grandest medical center of the ancient world.

At 28, he returned to Pergamon, his hometown and a major center for intellectuals and artists of the time. There, after eviscerating an ape and challenging multiple physicians to repair the damage, each of whom couldn’t, Galen performed the impressive surgery himself and won the opportunity to serve as the chief physician to the troop of Gladiators maintained by the High Priest of Asia.

After moving to Rome in 162 AD, Galen treated multiple affluent patients who had been proclaimed as incurable by other physicians. With wealth, great rhetorical skills, and a relationship with Eudemus, an old philosophy teacher, his reputation as a philosopher and physician advanced.

However, his impatience with others brought him into conflict with many Roman medical practitioners, and he feared that he’d be exiled or poisoned, eventually leaving the city.

Since human dissections were not allowed, Galen resorted to performing experiments and dissections on living and dead African monkeys, pigs, sheep, goats, and other animals. He believed that the anatomical structures of these animals mirrored those of humans, allowing him to gather insight and make inferences about the human body.

Even though Galen’s research was centered on animal physiology, this fact was lost in translation over time, and it took centuries for the academic world to realize that his work was a body of inferences and speculations about the human body that required corroboration.

Galen viewed the body as comprising three interconnected systems:

1. The brain and nerves (responsible for sensation and thought)
2. The heart and arteries (responsible for the life-giving energy)
3. The liver and veins (responsible for nutrition and growth)

From studying animals, Galen built upon Herophilus’ work and illustrated that the arteries also carry blood, not air. He distinguished seven pairs of cranial nerves, described the valves of the heart, established the functions of the spinal nerves, and demonstrated that the brain controls the voice by tying off the recurrent laryngeal nerve. He also depicted the functions of the kidney and bladder by tying off the ureters.

Another follower of Hippocrates’ Theory of the Four Bodily Humors, he believed that vital health required the four bodily humors— blood, black bile, yellow bile, and phlegm — to be in a state of equilibrium.

However, he added that humoral imbalances could be localized to specific organs, thereby improving diagnostic processes. Specifically, Galen felt that blood originates from the liver and is carried by the veins throughout the body, where it is transformed into flesh and other substances.

Alongside his landmark findings, the errors of Galenic physiology were difficult to challenge due to the prevailing disinterest in human dissections, and his work influenced the medical landscape for nearly 1,400 years.

Ironically, one of Galen’s greatest virtues—his emphasis on observing for oneself rather than relying on authority—was lost over time. Professors would read Galen’s work to their students, instilling many of the unfounded ideas into medical curricula for generations.

Eventually, Andreas Vesalius illustrated in 1543 that Galen’s version of human anatomy was more animal than human.

Andreas Vesalius [1514-1564] – The Founder of Modern Human Anatomy

After a 1,400-year duration that cemented Galenic concepts in the academic world, Andreas Vesalius, the Founder of Modern Human Anatomy and a pioneer who paved the way for modern medicine, reformed the discipline.

His contributions were so profound that it has been suggested that “few disciplines are more surely based on the work of one man than is Anatomy on Vesalius.”

Before Vesalius, the medical establishment taught students in a two-step process.

First, professors would read anatomical texts (mostly Galenic physiology) to students, followed by a surgeon’s demonstration of an animal dissection for students to observe. Having acquired his medical foundation under this practice, Vesalius had no reason to question Galen’s theories.

In 1541, however, Vesalius broke with the tradition of relying on Galen and openly began conducting dissections himself, relearning anatomy from cadavers and scrutinizing ancient texts —a practice that he also encouraged his students to follow to gain a deeper understanding of the human body.

In doing so, he came to recognize that most of Galen’s research had been restricted to animals.

Conducting human dissections for the first time in centuries, he began to rewrite anatomical text based on his own research. He drew attention to Galen’s errors and even faced resentment from many scholars and physicians of the time, who continued to regard Galen as a medical authority.

In 1543, Vesalius published the seven-volume De Humani Corporis Fabrica (On the Fabric of the Human Body), a landmark textbook of human anatomy that was based on live dissections and filled with highly detailed 2D illustrations.

The extensive and elegant nature of the 2D illustrations provided contemporary students and scholars with an immediate learning opportunity: the academic world could engage with highly detailed information for extended periods, ultimately resulting in a reorganization of the discipline.

This set of books contained Vesalius’ strongest claims against Galenic theories, bringing anatomists to rethink the skeletal, muscular, circulatory, and nervous systems. Supporting parallel dissections, Vesalius encouraged his students to dissect both an animal and a human cadaver simultaneously as a means of illustrating the differences between human and animal anatomy and disproving Galen’s assertions.

Among numerous other errors, Vesalius disproved the common belief that men had one fewer rib than women, as well as the Aristotelian concept that men had more teeth than women. Apparently, Aristotle and 1,800 years of successors never bothered to check their wives’ teeth.

Introducing human dissections into medical curricula, Vesalius led his work with fierce attention to detail, reorganizing man’s understanding with far-reaching implications for both physiology and biology.

The Impact on Medicine

Fewer theoretical scientific disciplines, like anatomy, have the potential to be reorganized again in the coming years (or centuries). For the most part, our understanding of the human body is constrained to what we see at a surface level.

However, imaging modalities that utilize infrared radiation and other forms of electromagnetic radiation allow insight to be gathered at a much deeper level. Future scholars may come to recognize details that we lack visual access to, turning the field on its head one more time.

It’s been said that sickness and disease are a language through which deviations from physical normalcy are expressed. The syntax of this language is rooted in anatomy class, and it is a massive historical feat that high schoolers can now delve deep into this material.