Les médecins administrent des médicaments dont ils savent très peu, à des malades dont ils savent moins, pour guérir des maladies dont ils ne savent rien. (Doctors put drugs of which they know little into bodies of which they know less for diseases of which they know nothing at all.) Attributed to Voltaire
When the Cobb County Georgia school board affixed a warning label to the county's adopted high school biology text book stating that "Evolution is a theory, not a fact," it was using theory in the everyday sense of "a hunch" such as the "newly released trailer for the next Star Wars movie inspires a million theories from fans about who Rey's parents are." [emphasis added] (Zimmerman, 2016)
But scientific theories are not hunches. A scientific theory is an explanatory argument about the natural world based on an extensive body of evidence drawn from observation and experimentation.
Think of a scientific theory as a map which instead of showing the relationships between towns, rivers, and mountains, shows how natural facts are related to one another. A scientific theory, like a map, is judged by how well it works. (Zimmerman, 2016)
The theory of evolution works because it provides testable explanations about the organisms in a specific environment.
But the view that a scientific theory should work has not always been a criterion for the acceptance of a theory-map.
For well over a thousand years, Europeans accepted the Hippocrates-Galen theory-map for disease with little evidence that it actually explained anything about disease and illness. Human health, according to the theory-map promulgated by Hippocrates (c. 460 B.C.E.), was dependent upon the four bodily fluids, blood, lymph, yellow bile (from the liver), and black bile. These fluids (also know as humors) supposedly determined not only our temperaments (sanguine, phlegmatic, choleric, bilious) but also our health.
Galen, a Greco-Roman (c. 100 C.E.) had perfected Hippocrates' map by matching the diseases that he saw in his practice to these four humors. For example: "Inflammation--a red, hot, painful distention was attributed to an over abundance of blood."
Cancer was the result of the action of the "most malevolent and disquieting of the four humors: black bile." The black bile was trapped in a particular site in the body and thus forming a congealed mass, the cancer. "Of blacke cholor [bile], without boyling cometh cancer," was how a sixteenth century surgeon applied the Hippocrates-Galen theory to what he saw in one of his patients. (Mukherjee, 2010, p. 48)
To account for diseases like plague or small pox, the Hippocrates-Galen theory attributed them to "miasmas" or polluted air which would upset the delicate balance of the humors and bring about disease.
As strange as it may seem the miasma theory accounts for the width of the streets in Columbia, South Carolina. When the city was designed in 1787, the founding fathers decreed that the streets of the city should be extra wide to permit winds to blow away the miasmas that would cause disease.
Of course, neither wide street to prevent fevers nor bleeding to reduce inflammation actually worked but that didn't seem to matter. "Galen said it and I believe it!" seemed to be sufficient for most physicians and surgeons well into the 19th century when discoveries by Pasteur in France and Koch in Germany finally proved that miasmas and humors were fantasies.
In the 16th, while the Hippocrates-Galen map continued to flourish, a quite different approach to knowledge began to take hold.
In place of the belief that true source of knowledge was ancient wisdom passed from generation to generation in books, there was a growing sense that real knowledge is based on experience; that is, direct experience (observation and experimentation). Observation and experimentation were supported by the use of mathematics and mathematical thinking to measure and to count. Further, empirical science was supported by formal and informal societies (the Royal Society of London, 1660; the American Philosophical Society, Philadelphia, 1743). (Gordon-Smith, 2010, pp.8-10)
The new empirical spirit was exemplified by Andreas Vesalius, who was born in Brussels in 1514. When he was 19, he went to the University of Paris hoping to become an expert in Hippocrates-Galen theory, and especially to master Galen's anatomical learning. He was shocked to find, not a systematic study of human anatomy, but instead an anatomy classroom that was a "macabre space where instructors hacked their way through decaying cadavers while dogs gnawed on bones and drippings below." (Mukherjee, 2010, p. 50)
Andreas found that there was in fact no human anatomy in Galen's books since his anatomical descriptions were based on dissections of Barbary macaques rather than on humans. A further barrier was the fact that there were no pictures in Galen's anatomy book, only descriptions copied and miscopied over and over again by monks, themselves ignorant of anatomy, and thus leaving physicians and surgeons "to hack their way through the human body like sailors sent to sea without a map--the blind leading the ill." (Mukherjee, 2010, p. 50)
Since there was in fact no anatomy, Vesalius took it upon himself to invent it. The cadavers for dissection came from the Paris public gibbet as well as from the pits where the plague victims had been hastily buried.
With real bodies for models, he created a series of highly detailed "atlases" (literally a collection of maps) of the body, the bones, the muscles, and even a series of a human brain sectioned resembling a CAT scan except that it was created with pen and ink.
Over his career he did thousands of autopsies (Greek for "to see for oneself").
During these investigation he found only part of the Hippocrates-Galen theory of humors: blood was easy, as was the pale and watery lymph and the yellow bile in the liver. But no matter how hard he searched he never could find the "black bile," the centerpiece of the Hippocrates-Galen theory of disease. (Mukherjee, 2010, p. 51)
The four humors and miasma theories, however, lived on despite Vesalius' accurate representations of human anatomy.
However, Vesalius' work did lay the foundation for the modern science of anatomy and provided confirmation that close observation of nature would yield valuable information. It was in the next century that William Harvey would conduct careful dissections of live rabbits that would lead him to explain the circulation of blood. Others like Cuvier would create a new line of investigation in comparative anatomy, in which similarities and differences between humans and other living organisms would be established. And in 1859 Darwin's Origin of Species would be published.
Godfrey-Smith, P. (2003). Theory and Reality: an introduction to the philosophy of science. Chicago, IL: University of Chicago Press.
Mukherjee, S. (2010). The Emperor of All Maladies: A Biography of Cancer. New York: Simon & Schuster.
Vesalius, A. (1543). Andreae Vesalii Bruxellensis, scholae medicorum Patavinae professoris, de Humani corporis fabrica Libri septem. Swiss Electronic Library. doi:http://dx.doi.org/10.3931/e-rara-20094
Zimmer, C. (2016). In Science, It’s Never ‘Just a Theory’. The New York Times, p. D6. Retrieved from http://www.nytimes.com/2016/04/09/science/in-science-its-never-just-a-theory.html
Dr. John Holton
Dr. John Holton joined the S²TEM Centers SC in July of 2013, as a research associate with an emphasis on the STEM literature including state and local STEM plans from around the nation.