When the New England Centenarian Study was started in 1994, there was only one individual more than 100 years old per 10,000 people in the United States and other developed countries. By 2012, there was one centenarian per 5,000 population. For children born today, some experts are predicting a 50 percent chance of living to age 100.

Much has changed to improve the odds you’ll become a centenarian, but what does it take to reach that milestone?

The New England Centenarian Study has been producing fairly convincing evidence that exceptional longevity – to age 105 and beyond – tends to be the result of genetics more than environment. For survival into the mid-80s, however, only 20 to 30 percent of variation can be attributed to heredity, according to twin studies.

Medicare said recently it will pay doctors to help patients plan what kind of care they want at the end of life, an idea more broadly accepted than six years ago when it touched off a political uproar about death

Lawrence Memorial Hospital is a major sponsor of WellCommons.

There are many research studies that suggest a person who follows healthy habits can expect a lifespan of 86 years or more. Life insurance companies have a pretty good handle on the factors that determine whether a person dies young or old. Some of the most important factors they track are weight or body mass index, drinking, smoking, driving record and stress management.

Smoking has been linked to many common causes of death: high blood pressure, heart disease, lung and pancreatic cancer, and chronic obstructive pulmonary disease (COPD). When Dr. Lester Breslow died in 2012 at age 97, he left behind a 70-year legacy of research and practice in public health and aging. As an official with the California Public Health Department in the 1940s and 1950s, Dr. Breslow conducted many of the early studies on the harmful effects of smoking that were later cited in the Surgeon General’s Report.

Dr. Breslow’s study of 6,928 residents of Alameda County proved with numbers the important effects of behavior on longevity. The seven recommended behaviors were:

• Don’t smoke.

• Drink in moderation.

• Sleep seven to eight hours a night.

• Exercise at least moderately.

• Eat regular meals.

• Maintain a moderate weight.

• Eat breakfast.

According to Dr. Breslow’s study, a 60-year-old following all seven recommended behaviors would be as healthy as a 30-year-old following fewer than three.

A study of older Swedes published in December 2013 in the British Journal of Sports Medicine found that persons who were physically active on a daily basis, even without exercise, had better cardiovascular health and lived longer than those who were less active. While moderate to vigorous exercise may be better at strengthening the heart muscle and lowering blood pressure, daily low level activity is also important. The ideal, of course, is to have both.

The diet most often cited as good for longevity is some form of the Mediterranean diet, emphasizing fruits, vegetables, whole grains, legumes, low-fat dairy products, fish and monounsaturated fats such as olive oil. The Mediterranean populations from which these diets come have a wealth of fresh, locally raised ingredients and take tremendous enjoyment in sharing good food with friends and family.

People who live to 90 or 100 generally have strong social support networks. Data compiled from 148 studies involving more than 300,000 subjects found that individuals with good social relationships were 50 percent less like to die over a study period that averaged 7.5 years. That amounted to an extra 3.7 years of life compared to a person with lower social support. The ideal is to have not one but several circles of support – family, neighbors, colleagues from work or school and friends from religious affiliation.

Most of us have genes that are both favorable and unfavorable to longevity. What matters most are the habits we adopt to make maximum use of our genetic background.

Janice Early is vice president of marketing and communications at Lawrence Memorial Hospital and can be reached at janice.early@lmh.org.