Think like a doctor, Part I

Remarkably accurate anatomical sketch by Vesalius

For nearly five years, I’ve been writing about medicine.  One of the questions I hear the most is, “when it comes to my health, who do I believe?”

Anyone who’s read my writing knows I’m critical of so-called alternative medical practices.  I’m also critical of the abuse of mainstream medical practices.  I’ve had years of education devoted to studying human medicine.  How is a layperson to know what works and what doesn’t, what is real medicine and what is hucksterism disguised as medicine?  Let’s explore how a non-physician can think critically and skeptically about health and medicine to make good decisions for themselves and their family.  In my mind, I’ve subtitled this series, “An Introduction to Medical Skepticism.”

The study of human medicine goes back, presumably, to the beginning.  Gods, spirits, ill-winds have always been invoked to explain illness.  “Malaria” means “bad airs”, even though we now know it’s caused by a small organism transmitted by mosquitoes.  As humanity became literate, human illness was studied and observations recorded systematically.  Hippocrates of Cos, who probably lived and practiced around the 4th century BCE, wrote excellent observations on the natural history of many common illnesses, descriptions that modern doctors easily recognize.

In the 15th century, Andreas Vesalius dissected cadavers, recording his findings in beautiful and mostly accurate drawings.  While human anatomy was probably well known to agrarians who slaughtered animals, and warriors, who slaughtered people, Vesalius’ writings and pictures provided one of the most accurate catalogs to date of gross (non-microscopic) human anatomy.  A century later, William Harvey gave the first complete description of the circulation of blood through the human body (probably; Ibn al-Nafis gave a partial description a couple of centuries earlier, while Europe was still immersed in the Dark Ages).

Through this time, as the anatomy and some basic physiology of the body was being described, real understanding of how the body works still eluded physicians.  Doctors, such as they were, still held to ancient beliefs on cause and effect, mostly described using the “humors” or “temperaments” model, attributing disease to imbalances of “black bile”, “blood” or other important substances.  A disease believe to be caused by excess blood could be treated by bleeding, for example.

It wasn’t until the 19th century that any real understanding of what we now call physiology began to appear.  This is when medicine began to become more frankly materialistic (in the sense of “not supernatural”).  At the time, it was widely believed that life was fundamentally different than non-life in that it was imbued with some sort of vital principle.  In 1828, chemist Friedrich Wohler synthesized urea, the first documented synthesis of an organic compound—compounds found in living things—from inorganic materials.  This was thought to be impossible, as organic chemicals were supposedly fundamentally different from inorganic ones, imbued somehow with a “life force”.

Wohler and his contemporaries showed that life is made of the same chemicals as everything else.  Scientists began to believe that the human body must act by the same laws and processes as everything else in nature (though many still held on to an idea of a “soul” or something like it).  Once it was realized that human beings were no different from any other part of the natural world, they could be studied without referencing ill humors or vital principles.  Scientists and doctors began to study the function of the human body and how we might use this new understanding to help people.

The 20th century birthed the practice of scientific medicine.  The Flexner report attempted to standardize medical education, something that could be done because of the shared understanding that medicine was now a science rather than a branch of religion. Deborah Blum’s The Poisoner’s Handbook follows doctors and chemists who use this new knowledge. Her narrative takes place in the early 20th century when doctors and chemists struggled to understand illness and death caused by poison.  Without an understanding of biology, chemistry, and physiology, these breakthroughs could never have taken place.  There was nothing easy and nothing supernatural about the discovery of how poisons worked and could be detected.  It took hard work and a thorough understanding of science.  From studying the damage done by poisons, they helped advance the science of how the human machine works.

Every advance we have made in preventing and treating disease is based on our understanding of the science of the human body. This combined with the use of statistical analysis has allowed us to live longer and healthier than our ancestors could have imagined.

In Part II, the piece that makes medical practice whole.


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