How to Have a Long Life

Scientific research has revealed a number of insights related to the length of human life. To a degree, one's lifespan is determined by inherited qualities in the genome. However, making lifestyle changes and taking specific actions can significantly lengthen one's life as well.

Some notable suggestions for controlling the aging process include:

• Consume fruits and vegetables, drink plenty of water, keep fat intake low, and emphasize complex carbohydrates in your diet.
• Regular exercise several days per week combats a number of maladies that are tied to aging, such as loss of muscle strength and loss of balance.
• Maximize your intake of antioxidants by eating foods including tomatoes, carrots, squash, spinach and blue and purple berries. Supplements can also help.
• The production of hormones such as estrogen in women and testosterone in women and men falls with age, so replacing these hormones is advisable.

Centenarians are those who have lived 100 years or longer. Although income has a well-documented positive relationship with life expectancy and overall mental and physical health, centenarians in the United States come from across the income spectrum. They are also found among all racial and ethnic groups and education levels.

Studies of American centenarians have indicated that these are people who, although encountering many stressors in their lives, have been able to move through difficult experiences with relative calm while maintaining a positive outlook. They engage in regular physical exercise, undertake mental challenges, do not smoke, keep their calorie intake and alcohol consumption under control, and eat plenty of fruits and vegetables as with a largely vegetarian diet.

In 2011 the countries with the longest life expectancies included Monaco, San Marino, Andorra, Japan, Singapore, Hong Kong, Australia, Italy, Canada, France and Spain. The longest life expectancy is enjoyed by Monaco, where the average person is expected to live an astounding 90 years. The shortest is Angola, at only 39 years. The biggest country in the top tier is Japan, at an average of 82 years.

In 2005, Andorra was the longest-living country, at 84 years of life expectancy. Andorra benefits from a relatively high amount of wealth per person, good sanitation and education. It also enjoyed a disease-free existence: in 2005 Andorra had an HIV/AIDS infection rate of zero.

Immediately after World War II, the Japanese had one of the shortest life expectancies in the world. Today Japan has one of the longest life expectancies, has the longest life expectancy for a country of its size, and has more centenarians per capita than anywhere else.

In 2004 it was reported that the Japanese eat a third fewer calories than the average North American. In addition, they get more exercise and lead a more physically active lifestyle. Japanese also benefit from a more egalitarian society where the social hierarchy is flatter and incomes are more equal than in many other countries. Studies have indicated that equality has a powerfully positive effect across many aspects of societies, including health outcomes.

The Japanese diet has been noted for its greater emphasis on fish, rice, soybeans and green tea, all of which contain numerous beneficial nutrients and chemicals for human health.

The longest life expectancies in Japan are found on the island of Okinawa. Okinawans consume a large amount of soy, such as tofu, which contains nutrients that are believed to reduce the risk of cancer and heart disease. They also consume a high amount of fish that contains omega-3 fatty acids, also reducing the risk of some forms of cancer and heart disease. Grains and vegetables also feature prominently in the Okinawan diet, while meat, eggs and dairy do not.

The lean and healthy diet, and a physically active lifestyle, along with a positive outlook together give the Okinawans long lives that are also relatively disease-free. Staying healthy in old age is especially important in extending life expectancy.

There is some debate on whether short people live longer. There is a gene known as the "Methuselah Gene" (Methuselah being a Biblical character who lived an extremely long life) that simultaneously causes short stature and a long life in its holders.

One major study from the 20th century indicated some unusual findings relating to aging and longevity. For instance, subjects of the study who were more cheerful and optimistic often took more risks and were more careless with their health, resulting in shorter lives than those who were more prudent and careful. This does not necessarily contradict the importance of a positive disposition overall, but rather clarifies that prudence and taking one's health and lifestyle seriously is vital, regardless of disposition.

In addition, men who stayed married over a long term outlived all other men. The second-longest-living group was men who never married. Those who were divorced or remarried were the worst off. By contrast, marriage and divorce did not have as significant an effect on women's longevity.

Some believe that rapidly advancing science and technology may soon enable human beings to repair the cellular and molecular damage inherent in aging, and thereby live extremely long, if not indefinite, lives.