Health is strongly related to environment. Put differently, the bases of population health are ecological (including climatological and agricultural conditions), social structural (this includes levels of inequality, population density, governmental protections of the poor, and trade circumstances, particularly in food and transportation capacity), and cultural (the worth of individuals, sense of social responsibility and civic morals – generally, the opposites of Social Darwinism). Population health is then a consequence of the internal organization of society and its complex of relations with its external social and physical environments. Upon this base rests the level and characteristic nature of societal health and disease, in a given age and place. Medicine is not typically considered to be part of this base. However, with the modern profession’s increased reach into the population via vaccines, hazardous prescription drugs, and dangerous hospitals, it can now be included as a negative effect on population health. 
The preceding blog established that, historically, in the West, medicine had no possible contribution to the decline of epidemic disease via its tools, ideas or discoveries. For example, the Little Ice Age (worst years: 1575-1730) was the result of planetary cooling caused by increased volcanic activity and a simultaneous decrease in sunspots.  Weather became tumultuous, more unpredictable and severe.
Temperature Chart of the Little Ice Age
These cold conditions (1675 was known as the year without summer) caused agricultural failures, grave food shortages and wars that, in turn, led to higher morbidity and mortality. About one third of the world’s population died.  French military records show that soldiers born in the second half of the 17th century averaged an inch shorter, and those born during the interspersed famine years were shorter still.  The malnutrition of those years lowered bodily resistance to contagious and chronic diseases.  During the cold years, European governments acted to the extent possible to get food to accessible segments of their populations. The cold years also sparked agricultural inventions and improvements that would bring about The British Agricultural Revolution: The Great Cheviot sheep was bred for its longer, more resilient wool; Charles Townsend (1674-1738) began crop rotation and animal waste fertilization so that fields did not have to lie fallow before replanting, Jethro Tull invented the seed drill whose principle advantage may have been the parsimonious use of seed, crop hoeing to rid fields of weeds that weakened crops, and he began what was to be a century-long series of improvements in plow design and technology. Such improvements in the plow enabled deeper plowing (making the field into a basin to catch rain and also turning
up insect larva to die in the cold of winter), and the newer plows had the capacity to plow harder soils.
As shown on the graph above, climatic warming began in the mid- to late 17th century. The subsequent lessening of harvest failures and use of the new farming techniques, led to longer life expectancy. Life expectancy, an indicator of disease-levels in society, began to increase in France near the end of the 18th century and in England near the beginning of the 19th century.  “As famine retreated from Western Europe, so too did the great epidemical diseases…”, even mortality due to infantile diarrhea declined during the 18th century.  All of this was planetary and societal, and very much bigger than what the English classified as the small ‘trade’ of medicine — with its incredibly fruitless ideas about disease and healing.
The Industrial Revolution Brings Forth a New Ecology of Disease
Many times the date given for the Industrial Revolution is 1730 (England). This date also marks the end of the Little Ice Age. However, industrialization was a country-by-country phenomenon. There have been many such national revolutions, and, in point of fact, they are still occurring. One can see a jump in British manufacturing output in 1730, and see the same jump about one hundred years later in the U.S. So, in America, urban populations grew from 1.8 million in 1840 to 54 million in 1920, in which year the U.S. census showed us to be just more than 50% urban. As each country had its Industrial Revolution, an urban disease ecology emerged. In between the manufacturing upshifts in England and the U.S., industrialization swept across Western Europe, and so did the sanitary movement. Often historians put the beginning of the sanitary movement in England at 1842, when Edwin Chadwick — a barrister-at-law and social reformer — published his famous “Report on the Sanitary Conditions of the Labouring Population and on the Means of Its Improvement”. The Report did not appear out of the blue, its political, economic and moral antecedents are dated in the Little Ice Age. Some of the techniques used to defend populations from disease (drainage, garbage removal, disinfection, quarantine) were much older.
The early processes of 18th century industrial development started a massive, long term rural-to-urban migration.
Manufacturing towns and cities were overwhelmed by population growth and new population density. Physical conditions became fouled and dangerous for the human organism, and various pathogen-borne diseases became
rampant. But the seeds of understanding the coldly practical side of population ill-health had already been planted in the cold years of mid-17th century. The full implications of high child mortality and the general weakening of the population by malnutrition and disease began to be comprehended as crucial economic and national security issues. Laborers were described as “cadaverous” in appearance, and as “ghosts” and “shadows”. Reckoning such morbidity, and with infant mortality ranging from 300 to 375 per 1,000 population, or higher,  no nation could hope to stay economically strong or to field capable soldiers and sailors.  Thus a nation’s population came to be seen, by the latter 18th century, as containing a finite supply of human ‘commodities’ worth preserving for their economic value. 
The Political and Ecological Changes
Then, later, as increased wealth entered industrializing systems, a given society would begin to reshape its physical and social environments based on old ideas and practices learned during the now subsided plague pandemics of the past. Behind this sanitary movement there was humanitarian concern, of course. And this motivation is still widely proclaimed. One suspects, however, it was the “security interests of the nation” — the interests of the wealthy and the powerful — that actually drove and financed the large-scale physical changes of sanitary reform (razing and rebuilding more salubrious housing, engineering canals, digging and bricking thousands of miles of drainage culverts).
General incomes rose because of labor shortages and unionization. Larger percentages of the populations of the then ‘developing’ Western countries were lifted from dire, absolute poverty. Because of the growing urban market, the relatively new agricultural techniques spread, and sustainable increases in crop production expressed the demand. Further, the technology of transportation (canals and then trains) allowed cheaper bulk shipments. As a result, food became more plentiful in crowded manufacturing cities. Sanitary theory and techniques dating back 500 years and much longer encouraged drinking water to be made cleaner.  ‘Sanitary’ housing (“…a purified, cleansed and aerated domestic space”) became more protective, keeping us from both disease vectors (e.g., rodents, mosquitoes) and extremes of weather. And our sewage was blessedly removed from our living areas. The result of development was lower birth and death rates, a phenomenon called the ‘demographic transition’ (so named by demographer Warren Thompson in 1929). Accompanying development with its sanitary reconstruction of society was the ‘epidemiological transition’ (so named by Abdel R. Omran in about 1967 ). The epidemiological transition refers to the decline of pathogen borne epidemic and endemic disease, and also included a decline in the infrequently mentioned parasitical and deficiency diseases. The transition brought a successive increase in chronic, systemic diseases such as cancer, heart disease and diabetes.
Wealth, Health and Inequality
“The present era of epidemiology is coming to a close. The focus on risk factors at the individual level — the hallmark of this era – will no longer serve. We need to be concerned equally with causal pathways at the societal level and with pathogenesis and causality at the molecular level.”
– M. Susser and E. Susser 
The social and physical environments were shown by the vast successes of the sanitary movement to be the foundations of disease and health. How we live collectively determines the likely causes of our deaths. If we cannot eat well enough, that alone can kill us; and, poor nutrition can increase our susceptibility to death from germs and parasites. If, in addition to a malnourished population, we live in conditions that are densely biologically assaultive, more of us will sicken and die from infection. Lessen and remove such vile conditions, make the environment more salubrious, and raging waves of disease subside.
Today, when we reverse those general improvements in the societal environment by entering a hospital, 1 in 25 patients gets an average of 1.1 hospital acquired infections; according to the CDC there are 35 million hospital discharges per year, thus about 1.4 million acquire an infection. These infections have a startling 11.57% mortality or 162,400 deaths annually from nosocomial infections. The total of hospital-based mortal, preventable adverse events has recently been estimated at 440,000 or one sixth of all deaths that occur in the U.S. per year.  That mortality magnitude is very close to the population size of Atlanta, Georgia.  Clearly, environment matters.
Enter the Inequality Ecology
As wealth reshapes society and the threats of epidemics, and death from pathogens, parasites and undernutrition recede, the proportional connections between increasing wealth and increasing indicators of health are lost. It is not that, no matter how wealthy a society becomes, eventually every member will die of something. Wilkinson and Pickett put it this way, “What has changed is that the improvements have ceased to be related to average living standards.” 
Wilkinson and Pickett describe a disconnection between wealth and health that is not a ceiling effect. That is, upon reaching some level of biological safety, we do not merely spend less. There is of course some of that alteration of proportion, but the economic pie keeps getting larger and we devote a larger share of the pie to health spending. The costs of health care increase (overhead, inefficiency, waste, technological changes), driving increased spending, but the effectiveness of health care does not increase in proportion with costs. Nor is the health-wealth disconnect merely the attainment of the biological limits of healthy longevity. For example: the U.S. is the wealthiest nation, we spend both more and proportionately more than any other nation on medical delivery, yet our ‘life expectancy’ and ‘healthy life expectancy’ (male and female) are shorter than any Western European nation, and including the UK, Canada, New Zealand and Australia. Even, Portugal and Greece, the two poorest nations of Western Europe, have longer life expectancies.  Why?
Wilkinson and Pickett provide a powerful, explanatory ‘structural’ variable:  economic inequality. As a nation’s wealth increases, less and less of that increase ever reaches the bulk of the citizenry. Given consideration of this variable, it should be no surprise that among the nations alluded to above, and by a considerable margin, the U.S. is the most economically unequal. Put simply: We pay more for medical delivery, but get ‘less bang for the buck’ (lower effectiveness, less patient safety), and what we do get is very unevenly distributed across the population (resulting in selectively higher rates of mortality and lower life expectancy). This is bigger than medicine.
It is true that “the medical establishment has become a major threat to health,” as Ivan Illich saw forty years ago,  and also true that the medical threat has grown. Nevertheless, the subsuming contextual fact is that where there is more inequality, there is less health, worse medicine and higher mortality.
The Golden Rule: Higher Median Income, Lower Poverty and Lower Inequality = Better Population Health
But each country must decide how to balance the things it values. For example, each country must decide the balance between accumulating rights, privilege and wealth in the hands of the few or spreading rights, privilege and wealth more widely throughout the population. The U.S. tends to value and legitimate economic inequality with our culture that favors ‘survival of the fittest’ over ‘love thy neighbor’. Using the Gini index (a common measure of income dispersion), among Western developed nations but including Japan, Israel and South Korea, the U.S. ranks highest in economic inequality out of 28 developed nations compared. The ratio of how much the richest 10% earn to how much the poorest 10% earn is another measure of economic inequality. Using that measure, of the richest 27 nations (income per capita range from $64,260 – $24,370), the U.S. is the most unequal. According to the CIA World Factbook, U.S. inequality is within the top one third of the 144 nations for which there is comparison data. We also have the highest child poverty rate. Apart from the effects of poverty, however, our inequality itself can be shown to have a strong, negative, independent effect on our indicators of relative healthiness.
In a comparison of all the nations in the world, the U.S. ranks 41st in life expectancy, 60th in maternal mortality, and 58th in infant mortality. (In 2015, however, the CIA ranked the U.S. infant mortality rate as 167th out of 224 nations.) A 2013 study showed that the U.S., when compared to 34 OECD countries, ranked 28th down from the best (Iceland) with our high premature mortality rate (YLL); only Poland, Slovakia, Estonia, Hungary, Mexico and Turkey had higher mortality rates. The U.S. life expectancy from age 50 years ranks 29th, with France Australia and Japan exhibiting the longest lives after fifty years. In a 2011 Commonwealth Fund comparison with sixteen other rich nations, the U.S. ranked highest (worst) in ‘mortality amenable to health care’.
In the latest Commonwealth Fund international comparison, the quality of U.S. medical delivery ranks 11th out of eleven nations (Austria, Canada, France, Germany, Netherlands, New Zealand, Norway, Sweden, Switzerland, and the UK). Yet we pay our physicians at least twice as much as any other country and our health care cost per capita is 2.5 times that of the first ranked UK.  These are examples of money being poured into medical delivery that does not go toward improving the average standard of care but rather contributes to the larger problem of economic/health inequality.
The relation of poverty to health is well established and much explored. The separate and even subsuming effect of inequality has not been elucidated to the same degree. The health outcomes noted in the above paragraph might be written off as peculiarly bad medicine in the U.S. However, international analysis and U.S. state-level data show two things clearly. (1) The positive effects from health-related spending diminish and disappear as inequality increases. (2) There is a robust, inverse causal association between variation in economic inequality and variation in health outcome measures.
The next blog will address the relation of economic inequality and population health in elucidating detail; yet, the topic begs much more research and theory.
Endnotes and References Cited M.A. Makary, M. Daniel. “Medical error—the third leading cause of death in the U.S.”, BMJ, 353:i12139, 2016; J.T. James. “A New, Evidenced-based Estimate of Patient Harms Associated with Hospital Care”, Journal of Patient Safety, 2013, www.journalofpatientsafety.com; J. Lenzer. “Unnecessary care. Is Profit driven healthcare to blame?” BMJ, Vol 345, 6 October 2012; J. S. Garrow. “How much of orthodox medicine is evidence based?”, BMJ, Vol 335, 2007; R. M. Klevens, et al. “Estimating Health Care-Associated Infections and Deaths in U.S. Hospitals, 2012”, Public Health Reports, Vol 122, March-April, 2007; P.C. Gotzsche. Mammography Screening. Truth, Lies and Controversy, Radcliffe Publishing 2012; M. Makary Unaccountable, Bloomsbury Press, 2012; H.G. Welch. Overdiagnosed, Beacon Press, 2011; Shannon Brownlee. Overtreated, Bloomsbury USA, 2010.
 H.H. Lamb. “Climate Fluctuations.” In Chapter 5, Volume 2 of The World Survey of Climatology, H. Flohn and H.E. Landsberg (Eds.) Elsevier, 1969; H Schneider and C. Mass. “Volcanic dust, sunspots, and temperature trends, Science, Vol. 190, 1975, pp741-746; M. Free and Alan Robock. “Global warming in the context of the Little Ice Age”, Journal of Geophysical Research, Vol. 104, Issue D16, 1999, pp. 19057-19070.
 A. B. Appleby. “Epidemics and Famine in the Little Ice Age”, The Journal of Interdisciplinary History, Vol. 10, No. 4 History and Climate: Interdisciplinary Explorations, (Spring) 1980, pp. 643-663.
 G. Parker. Global Crises: War, Climate Change and Catastrophe in the Seventeenth Century. Yale University Press, 2014, p. 22.
 Parker, cited above, p. 22.
 Appleby, cited above, p. 645.
 Appleby, cited above, p. 644. As Rene Dubos says, every disease has its time and place, so smallpox and syphilis increased.
 Abdel R. Omran. “The Epidemiological Transition: A Theory of the Epidemiology of Population Change”, The Milbank Fund Quarterly, Vol. 49, No. 4, Pt. 1, 1971, pp. 509-538. Reprinted with no changes in content or style in TMFQ, Vol. 83, No. 4, 2005, pp. 731-757; for author’s words on date see Figure 5 and Figure 7.
 These worried considerations about population began by about the mid-1600s. See the brilliant book by Mark Harrison, Disease and the Modern World, 1500 to the Present Day, Polity Press, 2004, pp. 58 – 71.
 Harrison, cited above, p. 65.
 Knowledge of the link between water quality and disease is old. A knowledge of water-borne pathogens — germs — is not necessary to raise health questions about drinking water. Upon turning into the Missouri River from the Mississippi River, the men of the Lewis and Clark Expedition (1804-1806) began experiencing diarrhea. The Missouri water was cloudy and contained visible particles and detritus. Captain Meriwether Lewis took a typically searching look at the river water, and told his men to fill their container from deeper below the surface where the water was far less clouded. The diarrhea resolved. See Stephen E. Ambrose. Undaunted Courage: Meriwether Lewis, Thomas Jefferson and the Opening of the American West, Touchstone, 1996.
 Abdel R. Omran. “The epidemiological Transition: A Theory of the Epidemiology of Population Change”, The Milbank Fund Quarterly, Vol. 49, No. 4, Pt. 1, 1971, pp. 509-538. Reprinted with no changes in content or style in TMFQ, Vol. 83, No. 4, 2005, pp. 731-757; for author’s words on date see p. 732.
 M. Susser and E. Susser. “Choosing a Future for Epidemiology: I. Eras and Paradigms”, American Journal of Public Health, Vol. 86, No. 5, May 1996, pp. 668-673.
 S. S. Magill, et al. “Multistate Point-Prevalence Survey of Health Care–Associated Infections”, New England Journal of Medicine, Vol. 370, 2014, pp. 1198-1208; J. T. James. “A New, Evidence-based Estimate of Patient Harms Associated with Hospital Care”, Journal of Patient Safety, Vol. 9, Issue 3, September 2013, pp. 122-128.
 Hospitals are not safe places, far from it. This is an old problem. Studies published in the 1960s showed that seven percent of all patients suffered compensable injuries while hospitalized, though few actually sued. Illich described such accidents as more likely than in all industries except mining and high-rise construction, but in proportion to the time spent in a hospital they are the most dangerous kind of place (I. Illich. Medical Nemesis, Pantheon Press, 1976, pp. 31-32). Illich goes on, using two studies, to tell us that one in fifty hospitalized children suffers an accident that requires specific treatment. Further, 20% of patients admitted to a research hospital acquires an iatrogenic disease, and that one case in thirty leads to death (G.H. Lowery. “The problem of Hospital Accidents to Children”, Pediatrics 32, 1963, pp. 1064-1068; J.T. Lamb and R.R. Huntly. “The Hazards of Hospitalization”, Southern Medical Journal, 60, 1967, pp. 469-472). Illich points out that any other business with a similar safety record would be closed. Physicians kill with near immunity from the consequences.
 R. Wilkinson and K. Pickett. The Spirit Level: Why Greater Equality Makes Us Stronger, Bloomsbury Press, 2010, p. 6.
 Global Burden of Disease Collaborators. “Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990-2013: quantifying the epidemiological transition”, The Lancet, Vol. 386, November 28, 2015, pp. 2145-2191.
 A structural variable is a variable that cannot be reduced to an attribute or condition of an individual. The individual can be poor but an individual cannot manifest inequality. Another individual can be wealthy, but cannot be unequal. Inequality can only manifest itself as a persisting relationship, and a structural variable is external to the individual. The important thing to realize is that structural variables cause effects that are independent from their components.
 I. Illich. Medical Nemesis: The Expropriation of Health, Pantheon Books, 1976.
 Karen Davis, et al. “Mirror, Mirror on the Wall: How the U.S. Health Care System Compares Internationally, 2014 Update”, http://www.commonwealthfund.org/~/media/files/publications/fund-report/2014/jun/1755_davis_mirror_mirror_2014.pdf .