September 5, 2013


Why Are You Not Dead Yet? : Life expectancy doubled in the past 150 years. Here's why. (Laura Helmuth, Sept. 5, 2013, Slate)

Clean water may be the biggest lifesaver in history. Some historians attribute one-half of the overall reduction in mortality, two-thirds of the reduction in child mortality, and three-fourths of the reduction in infant mortality to clean water. In 1854, John Snow traced a cholera outbreak in London to a water pump next to a leaky sewer, and some of the big public works projects of the late 1900s involved separating clean water from dirty. Cities ran water through sand and gravel to physically trap filth, and when that didn't work (germs are awfully small) they started chlorinating water.

Closely related were technologies to move wastewater away from cities, but as Grob points out in The Deadly Truth, the first sewage systems made the transmission of fecal-borne diseases worse. Lacking an understanding of germs, people thought that dilution was the best solution and just piped their sewage into nearby waterways. Unfortunately, the sewage outlets were often near the water system inlets. Finally understanding that sewage and drinking water need to be completely separated, Chicago built a drainage canal that in 1900 reversed the flow of the Chicago River. The city thus sent its sewage into the greater Mississippi watershed and continued taking its drinking water from Lake Michigan.

The germ theory of disease didn't catch on all that quickly, but once it did, people started washing their hands. Soap became cheaper and more widespread, and people suddenly had a logical reason to wash up before surgery, after defecating, before eating. Soap stops both deadly and lingering infections; even today, kids who don't have access to soap and clean water have stunted growth.

Housing, especially in cities, was crowded, filthy, poorly ventilated, dank, stinky, hot in the summer, and cold in the winter. These were terrible conditions to live in as a human being, but a great place to be an infectious microbe. Pretty much everyone was infected with tuberculosis (the main cause of consumption), the leading killer for most of the 19th century. It still has a bit of a reputation as a disease of the young, beautiful, and poetic (it claimed Frederic Chopin and Henry David Thoreau, not to mention Mimì in La Bohème), but it was predominantly a disease of poverty, and there was nothing romantic about it. As economic conditions started improving in the 19th century, more housing was built, and it was airier, brighter (sunlight kills tuberculosis bacteria), more weather-resistant, and less hospitable to vermin and germs.
We live like kings today--we have upholstered chairs, clean beds, a feast's worth of calories at any meal, all the nutmeg (people once killed for it) and salt we could ever want. 

But wealth and privilege didn't save royalty from early deaths. Microbes do care about breeding--some people have evolved defenses against cholera, malaria, and possibly the plague--but microbes killed off people without regard to class distinctions through the 1600s in Europe. The longevity gap between the rich and the poor grew slowly with the introduction of effective health measures that only the rich could afford: Ipecac from the New World to stop bloody diarrhea, condoms made of animal intestines to prevent the transmission of syphilis, quinine from the bark of the cinchona tree to treat malaria. Once people realized citrus could prevent scurvy, the wealthy built orangeries--greenhouses where they grew the life-saving fruit.

Improving the standard of living is one important life-extending factor. The earliest European settlers in North America suffered from mass starvation initially, but once the Colonies were established, they had more food and better nutrition than people in England. During the Revolutionary War era, American soldiers were a few inches taller than their British foes. In Europe, the wealthy were taller than the poor, but there were no such class-related differences in America--which means most people had enough to eat. This changed during the 1800s, when the population expanded and immigrants moved to urban areas. Average height declined, but farmers were taller than laborers. People in rural areas outlived those in cities by about 10 years, largely due to less exposure to contagious disease but also because they had better nutrition. Diseases of malnutrition were common among the urban poor: scurvy (vitamin C deficiency), rickets (vitamin D deficiency), and pellagra (a niacin deficiency). Improved nutrition at the end of the 1800s made people taller, healthier, and longer lived; fortified foods reduced the incidence of vitamin-deficiency disorders.

Posted by at September 5, 2013 5:36 PM

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