Understanding Da Vinci's Vitruvian Man

Leonardo da Vinci's understanding of the human body and its functions didn't come to him fully formed. Da Vinci studied human (and animal) anatomy for nearly two decades. Throughout his years of anatomical study, Leonardo examined every inch of the human body. He came to many conclusions, some right, some wrong — but all, in some ways, pathbreaking for his time.

Seeking proportion perfection

One of Leonardo's most famous illustrations, Vitruvian Man, which he drew around 1490, illustrates how he applied physical, mathematical, and mechanical principles to the human body (see Figure 1).

Vitruvian Man has become a pop-culture icon, featured in everything from the logo of a human research protection committee at the University of California in San Francisco to a major clue in Dan Brown's thriller, The Da Vinci Code.

Leonardo based his drawing on ideas from the ancient Roman architect Vitruvius and his ten-volume treatise De Architectura: The Planning of Temples, compiled at the close of the first century BC:

• The planning of temples depends on symmetry.

• This symmetry must be based on the perfect proportions of the human body.

• The human body has certain fixed proportions. For example:

• Four fingers make one palm.

• The face from the chin to the top of the forehead is a tenth of a person's height.

• The foot is a sixth of the height of the body.

• The palm of the hand from the wrist to the top of the middle finger is also a tenth part.

• The greatest width of the shoulders is a fourth of the body's height.

• The navel is the exact center of the body.

• The length of a person's outspread arms is equal to his or her height.

• If a person lies on his back with outspread hands and feet, and the center of a circle is placed on his navel, his fingers and toes will touch the circumference of the circle.

Basically, Vitruvius believed that the perfect proportion of a temple must correspond to the perfect proportion of a man: a man fitting his body into both a circle and a square.

Not surprisingly, Leonardo — despite the attempts of others before him — found this divine relationship of the rational (and geometrical) relationship of body parts to the whole person, which he illustrated in Vitruvian Man. He started with a perfectly proportioned man (using two young men as models) and then found the circle and the square within the figure. By correcting inconsistencies in previous drawings, he showed the triumph of empiricism (relying on observation and experimentation) over taking old belief systems for granted, without testing them firsthand.

Leonardo, however, took this idea of divine proportion a few steps further, applying his understanding of the structure of the human body to other patterns in nature. After all, as he put it, "Man is the model of the world." He established, for example, a relationship between the movements of the eye and the mind and the rays of the sun — though he wasn't always correct, he always had something interesting to say. Basically, Vitruvian Man represented Leonardo's larger attempt to relate the human form to the workings of the larger universe.

Testing your own little mug

The notion of beauty changes across time and cultures. However, studies have shown that beautiful people are more symmetrical and proportional than the average Joe. Physical symmetry generally reflects a person's youth, health, and fertility. And it all ties to evolution: In the past (like, 2,000 years ago), symmetrically shaped people had more babies.

To complicate the whole notion of beauty, researches have found a certain ratio that repeats in attractive things, from seashells and faces to the Great Pyramids, the Parthenon, and Leonardo's paintings. This golden ratio (also known as the Fibonacci ratio, the divine ratio, and the golden mean) is 1:1.61803399 . . . , with the 1.618 . . . known as phi. Studies have shown, for example, that the most attractive people have an ideal ratio between the width of the nose and mouth of 1:1.618.

Nothing definitively suggests that Leonardo was aware of phi per se, but he certainly knew about divine proportion and the beautifully proportioned human figure.

You can test out this symmetry idea yourself with a mirror and measuring tape:

• Your eyes should lie halfway between the top of your head and your chin.

• The bottom of your nose should be halfway between your eyes and chin.

• Your mouth should be halfway between your nose and chin, and the corners of your mouth should line up with the centers of your eyes.

• The tops of your ears should line up with your eyebrows, and the bottoms of your ears should line up with the bottom of your nose.

Hey, if you don't get the desired results, don't despair. There's always plastic surgery.