Q:  How long can a person really live?

A:  There are more than 70,000 people who are older than 100 in the United States, and people over age 85 are the fastest growing segment of the population. According to Dr. Mohsin Jaffer, a geriatric and aging specialist at Memorial Hospital West, a combination of good science, good genes and good habits have been the secret to our success.

    "In 1900 the life expectancy was little more than 40 years. For a girl born today it's 80, and for a boy it's a couple of years less," Jaffer says.

    The maximum average human life-span is usually cited as 120 years old. Scientists in search of longevity genes have actually found the opposite aging genes. The so-called SIRT genes are shared by most animals including humans, and they're believed to decrease life-span. The theory is if you don't have the aging genes, you may live a longer life. Many centenarians lack these aging genes.

    "If modern science and our genetic engineers can find a way to switch off that aging gene, we'll have a life in perpetuity and in youth," he says.