What the Doctor Ordered
•Philosophy and social theory
•Advances in biological knowledge
•Advances in data collection and
interpretation (Statistics)
•Advances in instrumentation and
medical techniques
Modern Medicine
• There has not been a really large-scale
epidemic since 1918-20 despite our high
population density
• Modern medicine remarkably effective
• Succeeded by reducing patient to
disconnected parts, often excluding patient
entirely from decision making.
The Irony of Early Medicine
• Every disease was considered unique
• Patient dictated treatment
• Sounds very much like what we now call
“holistic medicine.”
• Only problem: it didn’t work
• Why not? Insufficient Knowledge
– Body functions imperfectly known
– Role of micro-organisms unknown
– Case knowledge limited
Who’s a Doctor?
• Doctor = Latin, “teacher,” someone who
had learned subject matter well enough to
teach it.
• Medicine was late in being added to
university curricula
• Surgeons weren’t considered doctors until
about 1800
• Physicians took the title “doctor” from
professors, not the other way round.
William Harvey, 1628
• Estimate Volume of blood in heart, say two
ounces.
• Heart beats 100,000 times a day
• That means the heart pumps 200,000 ounces or
over 1500 gallons of blood a day.
• Clearly ridiculous – hence blood must circulate
• One of the earliest examples of “back of the
envelope” or “order of magnitude” calculations in
science. Use of rough calculation to rule out
hypothesis.
The French Revolution
• Tremendous need for battlefield physicians
• Many “Establishment” physicians purged or
fled
• Country surgeons called into service
• Emphasis on what worked, not on theory
• Ironically, many shortcuts were more
effective than traditional practice
• Lots of opportunity to make observations
Post-Revolution Medicine
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Surgeons were in charge
Hospitals were specialized
Emphasis on observation and practice
Doctors had automatic right to dissect cadavers
Patients had no power to control process or
object to treatment
– Poor
– Soldiers used to taking orders
– “My way or the highway” – patients who
objected could be discharged
Statistics
• Probability =
(ways event can happen)/(possible outcomes)
• One event or another (but not both): add
probabilities
• One event and another : multiply
probabilities
• Some outcome has to happen, regardless
how low the probability
A Few Common Statistical Fallacies
• Confusing order and probability
• Long runs do not make an event less probable
• Long negative runs do not make an event more
probable
• Spurious patterns
• Clusters don’t make events more or less probable.
• After-the-fact probabilities
• Treating non-random events as chance events
• Poor memory and fakery
Cholera and its Aftermath
• Cholera killed 22,000 in England 1831-33
• Riots and civil disorders sparked by poor
living conditions, sparked reforms
• William Farr, a government clerk, compiled
mortality tables that enabled doctors to
identify unusual death rates
• Farr noticed that cholera mortality
decreased away from the Thames but
suspected the stink from the river might be
the cause
The Birth of Epidemiology
• John Snow, 1853, began to suspect cholera was
connected to contamination by fecal material.
• John Simon, Medical Officer for London,
showed in 1855 that contaminated water was
the cause.
• In 1858 Parliament voted on a massive
rebuilding of the sewer system. Cholera
stopped and never returned.
• Nobody knew, even then, what specifically
caused cholera
What causes disease?
• Rising mortality in hospitals as operations
increase
• Cholera epidemic of 1830’s
• Approaches to contagion
– Bad air as cause (malaria from Latin for “bad
air”)
– Quarantine
– Some understanding of cleanliness but
insufficient to control disease
Louis Pasteur
• 1857: Studies fermentation
– Agent is alive and reproduces
– Agent can travel through air
– Food does not spoil if agent excluded
• 1864: pasteurization
• We finally know why food canning works
and how to prevent failures
• Link to decay a clue but also a trap
Fighting Germs
• 1850’s Ignatz Semmelweiss uses antisepsis
• 1865: Joseph Lister (son of inventor of
achromatic microscope) applies germ
concept to surgery, begins using carbolic
acid
• Identification of Disease Micro-organisms:
Now We Know What to Look For
• 1876: Robert Koch isolates anthrax bacillus
How Disease Survives
• Kill the host too quickly, the organism dies
out
• Pathogen and host evolve to coexist
(popular stereotype)
• Disease remains lethal but messy, to
facilitate spread (cholera, Ebola)
• Disease is lethal but has long mild phase
(AIDS) or residence in some other vector
(Ebola)
Why Did These Developments
Come So Late In History?
The Babylonians could have
measured blood pressure or
invented the stethoscope, so why
did it take so long?
Stimuli for invention
• Belief that observations could be
informative
• Belief that observations could lead to good
use
• Need Access to Body to Interpret
Observations
• Once progress began in finding causes and
cures of diseases, growth of medicine was
explosive
Poor optics were a real bottleneck
• Leeuwenhoek’s microscopes of the 1600’s
were astonishingly good, but still magnified
barely 100 times.
• Details of cell required the achromatic
microscope
Antisepsis and anesthesia require
some fairly advanced chemistry
• Alcohol is useful for both purposes but
naturally fermented beverages are not
alcoholic enough
• Distillation discovered by Arabs in Middle
Ages
• Nitrous oxide, ether, carbolic acid do not
occur widely in nature and all require
sophisticated chemistry to produce
Perpetual War
• Some bacteria are one drug away from
complete resistance to antibiotics
• Disease organisms evolve new defensive
and offensive strategies quickly
• We will probably always be devising new
strategies. So will the microbes.
• Conquer, co-opt or coexist?
• We are homogenizing the planet on a
geologically instantaneous time scale.