Why is it that the richest nation in the world doesn't also have the longest life expectancy?

American life expectancy surpassed 78 years in 2006, the latest data available, but it still lags behind 30 other nations. The good news is American life expectancy is improving faster than in the past. The increased life span can be attributed to falling mortality in the leading causes of death such as heart disease, cancer, accidents and diabetes. A reduction in flu-related deaths, due to a mild flu season in 2005, also helped boost the 2006 statistics.

Demographers say Americans may be catching up on leading nations after experiencing declines in the top 15 leading causes of death. Yet, it's somewhat difficult to comprehend that American life expectancy is similar to that of Portugal, the Republic of Korea, or Cuba, according to 2006 World Health Organization measures.

Could it be that America's affluence is a drag on overall health? A growing number of Americans are overweight, do not exercise regularly and do not eat healthful, well-balanced diets. America's love affair with the automobile has resulted in few communities that are truly walkable. Unlike previous generations that were required to take physical education classes in schools daily, the trend has been to scale back daily activity.

One highly disturbing trend reflected in the new U.S. data is that the life-expectancy gap between American men and women is closing because of increases in female smoking rates. This is troubling given changes in state law and local ordinances to discourage smoking, let alone intensive anti-smoking campaigns funded by a legal settlement between some major tobacco companies' and most states.

Much of the life-span improvements can be attributed to better medicines and treatments of diseases and injuries. Infant mortality rates also dropped, which improved overall statistics.

Imagine the possibilities if Americans paid stricter attention to childhood immunization records, obtained flu shots each year and adhered to a healthful lifestyle.

Medical science can do only so much to increase life span. No one can escape their own genetics, but all can take steps to improve their individual health, thus increasing the likelihood they will not develop certain conditions such as heart disease, diabetes and some cancers that tend to reduce life spans.