Lessons from Leonardo: What makes a great scientist great?

In the normal course of events many men and women are born with various remarkable qualities and talents; but occasionally, in a way that transcends nature, a single person is marvelously endowed by heaven with beauty, grace, and talent in such abundance that he leaves other men far behind, all his actions seem inspired,and indeed everything he does clearly comes from God rather than from human art. — Giorgio Vasari. Lives of the Painters,Sculptors and Architects, 1568

Leonardo da Vinci (1452-1519) was an artist, architect, engineer and scientist. But today, he is best known for his sculptures and paintings – the Mona Lisa alone averages 15,000 visitors a day, most of whom have traveled a long distance to take a snapshot of the world-famous masterpiece. However, the exhibit of Leonardo’s anatomical drawings at the Royal Collection portrays Leonardo above all as a scientist, at least in the second half of his life – with painting placed largely to the side. More importantly, this exhibit shows that the scientific methods of deduction and experimentation employed by Leonardo remain applicable today.

Leonardo’s aim was to record the birth, life, and death of man in his Treatise on Anatomy, begun in 1489. However, he was a perfectionist and did not have time to publish his work before his death in 1519. Pompeo Leoni, an Italian sculptor, bought Leonardo’s sketches and notes in 1580 and had them bound into several albums, one of which featured all of Leonardo’s anatomical drawings. The album was acquired by the Royal Collection by 1690 and stored at the Royal Library at Windsor Castle.

This year the Royal Collection has put on display at the Buckingham Palace 87 pages of Leonardo’s notebooks, full of detailed notes and anatomical illustrations. Although he annotated his illustrations, it was drawing that became the true means of explanation for him. Every page shows meticulous notes in mirror writing surrounding detailed drawings and diagrams of bones, organs, vessels and muscles. The mirror writing was not used to keep his ideas secret, for Leonardo had every intention to publish his work. It is speculated that it was easier for him to write like so given that he was left-handed. Perhaps it was meant to slow him down, at least initially, so that he could think clearer and reason better. Or perhaps this was just another quirkiness of his – and I say this fondly.

The exhibit reveals Leonardo full of characteristics that make a man a true scientist. A man born over half a millennia ago is able to teach us about the conduct of modern clinical research.

Study of the Heart

Remarkably, Leonardo understood that in biology structure relates to function and he took this into account all throughout his anatomical studies. Evolutionary changes result in remarkably complex structures that elegantly match their physiological function. By studying the structure of an organ, one begins to answer questions about its function. The lungs, for example, are made as “balloons” enabling the intake of oxygenated air and the removal of air containing carbon dioxide. The concept of the structure-function relationship was drilled into my head throughout my biology studies – this man figured it out over five hundred years ago.

These few examples of Leonardo’s investigations of the heart and the circulation serve to show the meticulous way he observed, considered, and recorded his work. He came extremely close to understanding how blood moved through the body, a mystery that was not fully solved until 1628, more than a century after his death.

Leonardo’s techniques for understanding the heart were sophisticated – he injected molten wax into the aortic valve. Doing so, he noticed a swelling at the base of the valve, now known as the sinus of Valsalva. He built a glass model of the heart from his wax cast, injected water with a grass seed suspension, and noticed circular vortices in the swollen section. From this he concluded that the swelling aided the directional flow of blood downstream from the valve.

Leonardo was a forward-thinking man and these observations were only confirmed in the 1980s with modern imaging technology. He clearly understood the function of the heart valves in a one-way system, and must have struggled to reconcile this with the prevailing wisdom that the veins and arteries were separate.

Studies of the coronary vessels and valves of the heart, 1511-13

Drawing of a Skull

His drawings of a skull (1489) splits the skull into two planes, coronal and sagittal, resulting in a detailed three-dimensional account of the human skull. Leonardo was the first to draw a three-dimensional depiction of the parts of the dissected body. Impressively, his drawings are no less schematic than modern 3D models of the human body.

The meticulous drawing is tiny, no larger than 19 X 13.7 cm.

“A skull sectioned” by da Vinci. The Royal Collection 2011, Her Majesty Queen Elizabeth II.

Closeup: arrangement of the teeth and dental formula of one half of the mouth.

The skull depicted above was the first human skull that he acquired. Up until then he had been relying on previous recordings. Here, Leonardo begins to rely on his own observations. On the left side of the drawing of the skull, Leonardo sketched the arrangement and morphology of the teeth as present in a right upper quadrant of the mouth (see right for closeup). From right to left: an incisor (4), a canine (2), a premolar (4), and a molar (6).

Leonardo was the first to describe the human dental formula and the first to accurately describe the number of teeth in the human as 32, a topic that had largely been debated a the time. It is fascinating to witness Leonardo’s progress and to see how he revised beliefs.

Amusingly, Leonardo regarded the medical profession of the day with great skepticism. He wrote, “Endeavor to preserve thy health in which thou wilt succeed the better the more thou guardest thyself from the physicians. For their mixtures area kind of alchemy on which there are no fewer books than there are remedies”. In this short comment he demonstrates not only his suspicion of the medical profession of the day, but also the importance of evidence-based medical practice.

The Woman’s Uterus

“Science comes by observation, not by authority” – Leonardo.

Like a modern good scientist, Leonardo strove for objectivity. For the most part, he managed to detach himself from ancient Greek and Roman writings that predominated 15th century Italian thought and learned to rely on himself. Of course this was not always easy. Although the Church did not prohibit human dissection, as an artist Leonardo had limited access to bodies. Before his reputation started growing in the 1500s, he relied on animal dissections. This would have put him at a disadvantage and some of his drawings illustrate that where information was unknown, Leonardo was swayed by common beliefs circulating at the time.

Cardiovascular system and principle organs of a woman, 1509-10

This famous drawing attempted to show all the internal organs of a woman, except the gastrointestinal tract. There is a two-chambered heart with only ventricles, as well liver, spleen, and kidneys. However, the uterus remains highly inaccurate. It is depicted with seven chambers, following the thoughts of Aristotle, and is suspended by massive ligaments transcribed from a cow. Leonardo often used corpses of executed criminals for his anatomical studies. These tended to be male and female parts were often derived from animals instead. The female uterus here, is substituted with cow’s structures.

The drawing shows the difficulty of reconciling traditional beliefs. It is fascinating to see that there were some topics which remained mysterious to him – his drawings and notes take us on his journey of exploration and thought.

Study of a Fetus

Like any great scientist, Leonardo was forward thinking: he not only made observations, but raised questions in the attempt to understand how humans function. This was a novel concept for anatomy and Leonardo’s work remains an important milestone in the history of medicine. Leonardo has often been described as the archetype of the Renaissance man, a man of “unquenchable curiosity” and “feverishly inventive imagination”. This is very much illustrated by the exhibit. For example, he was fascinated by how human reproduction happens and his embryological studies illustrate his attempts to answer this question.

Leonardo was the first to accurately draw the child in the womb. He was the first to observe and comment on the fetal membranes—the chorion, amnion, and allantois.

However, his fetal drawings also betray his lack of access to female corpses. His fallopian tubes connect to the womb from below, when in reality they come from above. The drawing also reveals multiple placental membranes, which are found in cows but not in humans. This iconic image is a chimera, a fusion of a cow with a human. This represents a recurring problem in biology – researchers depend on the availability of tissue that they intend to study. If tissue is scarce, studies cannot be effectively completed.

“In the case of this child the heart does not beat and it does not breathe because it lies continually in water. And if it were to breathe it would be drowned, and breathing is not necessary to it because it receives life and is nourished from the life and food of the mother.” – wrote Leonardo

Study of Bones and Muscles

In the winter of 1510-1511 he returned from the countryside to Milan where he began collaborating with a Professor of Anatomy, Marcantonio della Torre, at the University of Pavia outside Milan. This made further work much easier – he had the help of a specialist and a wider access to human corpses. It was during his time working with della Torre that Leonardo completed his illustrations of bones and muscles (see below). Unfortunately this was a very short-lived relationship, as Marcantonio died of the plague in 1511. This short period in Leonardo’s life highlights another key aspect of modern biology research – collaboration is key.

Bones and muscles were easier to understand than internal organs, and required less wrestling with traditional medical beliefs – he could simply examine, observe and draw. At this time, Leonardo developed a rotational system of drawing, showing bones & muscles from various angles. A particularly intricate drawing of the spine was given the full architectural treatment in top, side and exploded views, below.

The vertebral column, 1510


More About Leonardo

Leonardo left almost no stone unturned. He was interested in botany, geology, cartography and anatomy. In 1478 he designed a self-propelled car – it was not exactly a passenger car, but the machine worked like a robot, or a wind-up toy: rotating the wheels opposite of their intended direction winds up the springs inside, giving the machine power.

Da Vinci’s imagination was filled to capacity with ideas for flying machines, including several gliders equipped with flappable wings. He designed diving gear, including a diving suit made of leather and connected to a snorkel made of cane and a bell that floated on the surface. The suit included a pouch the diver could urinate. He was a practical man, full of original thoughts and insight.

I highly recommend a visit to the exhibit. His drawings are so good, so small, so precise that it makes it near impossible to believe he drew them by hand. You’re shown into the mind of an incredible thinker and this leaves you feeling inspired. If you don’t live in London, don’t despair. You can now buy the Leonardo da Vinci: Anatomy application for the iPad. Tap on the 3D human body to find Leonardo’s drawing relating to that area and explore over 250 of his drawings. Is he turning in his grave, at the thought of you learning his story through 11 chapters and interactive demonstrations all from the comfort of your own couch? My bet is that he would encourage you – his intention had been to publish his work, but his belief in perfection and death meant that he never got to see his work in print. If you get the chance do go visit the exhibit for an inspiring journey into the mind and works of a genius. Hurry hurry, the exhibit finishes October 7th!

Sources

- Leonardo da Vinci: Anatomist exhibit at the Queen’s Gallery, Buckingham Palace.
Leonardo da Vinci’s “A Skull Sectioned”: Skull and dental formula revisited.

4 thoughts on “Lessons from Leonardo: What makes a great scientist great?

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  2. Pingback: Anatomical Architectures – Sculptures by Federico Carbajal | PharmaKon

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  4. Pingback: Art inspired by cadaver cross-sections.. neuroculture continues to transpire. | PharmaKon

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