Dr. Tom Perls is a physician and researcher in the study of aging at Boston University Medical School. For the past ten years he has directed the New England Centenarian Study (NECS, www.BUMC.bu.edu/centenarian), becoming one of a handful of the world's experts studying people who reach 100 years of age. There are about 40,000 centenarians in the United States, or a little more than 1 centenarian per 10,000 in the population; 85 percent of them are women, and 15 percent are men.

How important are genes when it comes to longevity?

The vast majority of human beings are "built" to live into our mid-to-late eighties. For men that means about 88 years, and for women, about 90 years. Genes account for about 30 percent of that ability and the environment about 70 percent.

What are some of the "symptoms" you have observed of extreme longevity?

We've discovered that people who live longer seem better able to cope with their illnesses. Centenarians have good health into their nineties, and a notable lack of diseases until just a few years before their death. For women, the ability to bear children late in life is something we've noticed -- and more women than men live long lives.

What do you mean by "genetic advantage"?

We all basically have the same genes, but there are tiny, differing variations that contribute to how we look or act differently. These variations interact differently with the environment, and some people seem to have just the right combinations to win the longevity lottery! Even if a person is exposed to the worst of environments, they can still reach extreme old age with the right combination of genes. In contrast, people with minimal genetic advantage levels are unlikely to reach extreme old age, no matter how well they control their environment.

Do some people have genes that slow down the aging process?

In the longevity marathon, many people can get to the ninth and tenth laps through a combination of good genes and good "training" - a healthy lifestyle that includes exercise, proper diet, and antioxidant supplements. People who live to their seventies, eighties, and nineties in good health can make up for less protective genes by forming good health habits and avoiding unnecessary hurdles, like smoking, excessive alcohol use, and sun exposure. But people who live to 100, particularly men, must have an extremely strong set of genes that protect them from damage from internal and external sources, such as free radicals and environmental hazards.

In our research, the long-lived families we discovered have a relatively small number of advantageous genes. The possibility of identifying these opens the door to discovering how these genes exert their influence, and even to understanding how the process of aging occurs. This is the "holy grail" of this research: Are there genes that slow down the speed of aging? I think there must be.

How can people learn about their genes, and what can we do to make the best of them?

Look at your family history. Are there people in your family who have lived into their nineties or even to 100? If so, you have a huge benefit going for you already. Next, analyze why others in your family did not live as long. Did they have a poor diet? Did they not exercise? Did they smoke? What kind of environment did they live in? Did they have access to clean water, high quality food, safe neighborhoods? You have control over many of these things, and you can extend your life by paying attention to them.

Use the Eons Longevity Calculator now, and you will discover lots of factors that can influence your ability to live a long life.