The inflection point

Okay, pretty correct answers from our two commenters on the previous post. Not just chlorination, but clean water generally, i.e. sewage treatment and separating sewage from drinking water sources. Also pasteurization of milk was very important. But the story is a bit more complicated. Pre-industrial people were mostly rural, obviously drank their milk fresh and didn't have a lot to fear from waterborne diseases since their population was sparse. Obviously they did suffer greatly from other plagues -- the Black Death killed something like half the population of Europe in the mid-14th Century, and plague recurred in lesser epidemics thereafter. Smallpox was another big killer. 

 

But by the 19th Century, people had learned to control plague by isolation and quarantine, and smallpox vaccination was becoming commonplace. In any case, even before then, life expectancy and population growth were limited between infectious disease outbreaks by the Malthusian trap -- any increase in agricultural productivity, or in the availability of land per capita because of a plague, would immediately result in a population increase that used up all the surplus. People were commonly malnourished and at a bare level of subsistence.

 

That started to change by 1776 (auspicious year?) when James Watt made important improvements to his steam engine, putting in process the Industrial Revolution. England could now achieve prosperity even for a growing population, by using fossil fuel power to spin and weave, transport goods, and  otherwise process and manufacture. That was also the year of publication of Adam Smith's The Wealth of Nations, which noted a process that had already begun of moving production from households to more efficient investor-owned factories, which was greatly accelerated by steam power.

The explosion in productivity, combined with vaccination, should have resulted in rising life expectancy, but the Industrial Revolution also caused people to crowd into cities where factory work as to be found, and there they died of infectious diseases as fast as the population could be replaced by new arrivals from the countryside. Life expectancy in the U.S. actually declined from 1800 to 1850. By mid-century, 60% of all deaths in New York City were of children under 5. One major culprit was cow's milk. Because women were participating in the factory labor force, a lot of children drank it, and it was often contaminated with bovine tuberculosis, diphtheria and typhoid.

Louis Pasteur and other scientists developed the germ theory of disease in the late 19th Century, and Pasteur invented pasteurization in the 1860s. But it wasn't until the early 1900s that a wealthy campaigner named Nathan Strauss succeeded in convincing cities to require pasteurization of milk. Widespread chlorination of drinking water happened at the same time. More vaccines were also developed in the early 20th Century. And so people no longer expected half of their children to die, and we started to assume that most people would live out at least their three-score years and ten.

But I want to draw your attention to one category of professional that had nothing to do with this: physicians. The germ theory of disease did teach doctors to sterilize their hands and instruments, and thereby stop killing new mothers and having better luck with surgery, but it didn't give them any effective ways of actually treating disease until effective broad spectrum antibiotics became available during and after World War II. There have been astonishing advances in the science and practice of medicine since then, and it has become somewhat more important to population health and life expectancy, but it's still somewhere less than half of what matters. (It's hard to quantify exactly.) 

The point I want to set up with this story is that we are spending enormous and growing amounts of our national wealth on medical intervention, but we aren't spending nearly enough on what really matters for our health, well being and long life. Next I'll offer some musings on why that is.