Lifespan has doubled in North America in the past 150 years. This ridiculously wonderful change in the nature of life and death is something we tend to take for granted. When we do think about why we're still alive, some of the big, fairly obvious reasons that come to mind are vaccines, antibiotics, clean water, or drugs for heart disease and cancer. But the world is full of underappreciated people, innovations and ideas that also save lives. A round of applause, please, for some of the oddball reasons, in no particular order, why people are living longer and healthier lives than ever before.
COTTON. One of the major killers of human history was typhus, a bacterial disease spread by lice. It defeated Napoleon's army; if Tchaikovsky's 1812 Overture were historically accurate, it would feature less cannon fire and more munching arthropods. Wool was the clothing material of choice before cotton displaced it. Cotton is easier to clean than wool and less hospitable to body lice.
SATELLITES. In 1900, a hurricane devastated Galveston, Texas. It killed 8,000 people, making it the deadliest hurricane in U.S. history. In 2008, Hurricane Ike hit Galveston. Its winds were less powerful at landfall than those of the 1900 storm, but its storm surge was higher, and that's usually what kills people. This time we saw it coming, thanks to a network of Earth-monitoring satellites and decades of ever-improving storm forecasting. More than 100 people died, but more than one million evacuated low-lying coastal areas and survived.
FLUORIDE. There were plenty of miserable ways to die before the mid-20th century, but dying of a tooth abscess had to be among the worst -- a slow, painful infection that limits your ability to eat, causes your head to throb endlessly, and eventually colonizes the body and kills you of sepsis. Now it's a rare way to go, thanks to modern dental care, toothbrushes, and (unless you're in Portland) fluoridated water.
WINDOW SCREENS. Houseflies are irritating today, but they used to be major vectors of deadly diarrheal disease. Clean water and treatment of sewage eliminated the most obvious means of transmitting these diseases, but pesky houseflies continued to spread deadly microbes. By the 1920s, according to James Riley in Rising Life Expectancy: A Global History, a growing aversion to insects and the introduction of window screens reduced this risk.
BOTTS' DOTS. Those raised ceramic reflectors between road lanes were invented by Elbert Botts, a chemist who worked for the California Department of Transportation. The dots help motorists see the edge of their lane even in the dark or when it's raining. Botts died in 1962, four years before the first Botts' dots were installed on California highways.
MORBIDITY AND MORTALITY WEEKLY REPORT. That's the no-nonsense name of one of the most important publications most people have never heard of. The Centers for Disease Control and Prevention has been publishing it since 1952 to provide "timely, reliable, authoritative, accurate, objective, and useful public health information and recommendations." When a new disease or danger emerges -- such as AIDS or a new strain of influenza -- the MMWR is often the first to identify it.
AIR-CONDITIONING. Heat is deadly and we don't respect it enough. A Chicago heat wave killed more than 700 people in one week in 1995. In the U.S., the National Weather Service issues heat alerts, and cities have started to offer air-conditioned cooling centres for people who would overheat at home. A recent study shows air conditioning has cut the death rate on hot days by 80 percent since 1960.
PASTEURIZATION. This should be an obvious lifesaver, right up there with hand-washing and proper nutrition. But the rise of the raw milk movement suggests a lot of people take safe dairy products for granted. Contaminated milk was one of the major killers of children, transmitting typhoid fever, scarlet fever, diphtheria, tuberculosis and other diseases. One of the most successful public health campaigns of the late 19th and early 20th centuries was for pure and pasteurized milk -- so successful we don't really remember how deadly milk can be.
SHOES. Hookworms are parasites that enter the human body through bare feet -- often by biting into the soft skin between the toes. The disease was common in the Southeast, spread when people walked barefoot across ground that was contaminated with feces of people who were already infected. Education initiatives at the beginning of the 20th century encouraged people to build sanitary outhouses and wear shoes.
COWS. The Midwest once had some of the worst malaria outbreaks in the country. Anopheles mosquitoes had always flourished in the damp lowlands around streams and melting snow, and when settlers came, some of them carried Plasmodium parasites the mosquitoes spread widely. The settlers' farming practices made for even more stagnant water, and their sod and log houses were perfect habitat for biting pests. After farmers had exhausted the soil, they started raising cows rather than crops -- and mosquitoes prefer to suck bovine blood even more than that of humans, helping break the malaria cycle.