Babies born in the United States in 2005 are expected to live an average of 77.9 years, according to a 2007 study by the national Centers for Disease Control and Prevention's National Center for Health Statistics. That's an increase of more than 30 years since 1900, when Americans were expected to live just 47.3 years [source: Medline Plus]. While the increase is impressive, America is not at the top of the list for life expectancy. Actually, the United States ranks behind 41 other countries.
Residents of Okinawa, a Japanese island, have long been endowed with high life expectancies. In 2002, there were 34.7 people 100 years or older per 100,000 residents, the highest life expectancy of any area in the world [source: USA Today]. People so envy Okinawans' vitality that doctors created a popular diet based on theirs to help others try to live longer. Still, while Okinawa may feature the highest population of centenarians -- people who are 100 years of age or older -- Japan is ranked second in life expectancy with an average of 82.
So to whom does the honor of first place go? It's a country you may never have heard of. The residents of Andorra, a tiny mountain nation in the Pyrenees between France and Spain, are expected to live to the ripe old age of 83.5. But why are Andorrans expected to live so much longer than anyone else? And how can you calculate something as unpredictable as how long someone will live?
Roughly the same area as New Orleans, La., or Warsaw, Poland, Andorra is home to around 72,000 people. It was established in 1278, but was a co-principality -- ruled jointly by Spain and France -- until 1993, when it became a democracy.
It was generally a poor country until after World War II, when Andorra reinvented itself as a tourist destination for skiing. Now, with a gross domestic product (GDP) -- the total of all of the goods and services produced in a year -- of $2.77 billion U.S., Andorra has what the CIA characterizes as a "well-to-do" economy.
But wealth alone doesn't grant a lengthy life expectancy. The United States is one of the world's richest countries, with a GDP of $43,500 per person. Andorra has a per capita GDP of $38,800 [source: CIA]. Read about other factors that affect life expectancy on the next page.
Life Expectancy Formulae and Factors
Researchers examine death certificates to calculate life expectancy statistics. From these, they cull age, race, gender, reason for death and other data related to a person's death. When combined with census numbers, these data help calculate an average life expectancy for a national population. Life expectancy data can also be broken down by criteria such as gender, and divided even further into more specific groups as needed.
Life expectancy is a raw statistic, but what factors influence these statistics? A wide array of characteristics -- some unique, others universal -- make a population and its life expectancy what they are. Multidisciplinary population studies help sociologists, economists, psychologists, statisticians and public health professionals learn more about who people are.
The prevalence of disease within a population has an effect on the average life expectancy. The World Health Organization (WHO) reports that, in 2005, 38 percent of the adult population of Swaziland, the African nation with the lowest life expectancy in the world, was inflicted with AIDS or HIV. This alone doesn't account for Swaziland's low average life expectancy (38 years for men and 37 years for women), but it has a tremendous impact. Zero percent of the population of Andorra, on the other hand, has AIDS or HIV [source: WHO].
The prevalence of AIDS in Swaziland displays how factors affecting life expectancy are intertwined. Residents of the African nation have less access to health care than Andorrans, in large part because of poverty. Swaziland has a per capita gross domestic product of $5,300, and 69 percent of its residents live below the poverty line.
Poverty also prevents access to safe drinking water and sanitation. Eighty-seven percent of Swaziland's urban population and 42 percent of its rural population has access to safe water. The numbers are similar for access to sanitation. Conversely, 100 percent of both Andorra's rural and urban population has access to safe water and sanitation. One reason it's easier to provide Andorrans with better sanitation is because of the country's size: Fewer people require fewer sewers, and the country saves money on installation and maintenance costs.
Education is another factor that contributes to a longer life expectancy. Only 81 percent of Swaziland's population of more than 1 million people is literate, compared to 100 percent of Andorra's residents. Andorra also has a 100 percent employment rate for its 42,420-person-strong labor force.
So Andorra is smart, small and wealthy. Its people have access to good water, sanitation and health care. But there is at least one other factor that affects the life expectancy of Andorrans: They don't have to worry as much about being killed in an act of god -- their only natural hazards are avalanches.
For more information on populations and age, visit the next page.
Science and medicine is allowing us to live longer and longer. Learn when average life expectancy will hit triple digits at HowStuffWorks.
More Great Links
- Olemacher, Stephen. "41 nations top U.S. life expectancy." Associated Press. August 12, 2007. http://seattletimes.nwsource.com/html/health/2003832640_life12.html
- Wiseman, Paul. "Fabric of a long life." USA Today. Janurary 3, 2002. http://www.usatoday.com/news/health/2002-01-03-usat-okinawa.htm
- "Andorra." CIA World Fact Book. November 15, 2007. https://www.cia.gov/library/publications/the-world-factbook/geos/an.html #People
- "At a glance: Andorra." UNICEF. http://www.unicef.org/infobycountry/andorra_statistics.html
- "Country health system fact sheet: Swaziland." World Health Organization. http://www.afro.who.int/home/countries/fact_sheets/swaziland.pdf
- "Highlights on health: Andorra 2005." World Health Organization. March 28, 2006. http://www.euro.who.int/eprise/main/who/progs/chhand/home
- "U.S. life expectancy hits new high." Medline Plus. September 12, 2007. http://www.nlm.nih.gov/medlineplus/news/fullstory_54725.html