Aging Causes: Nature or Nurture?

The complexities of getting older make it difficult to pinpoint why one person ages well while another looks and acts older than his years. Are good health and fortitude passed down like blue eyes and blond hair? Or are they a product of the environment, including the food you eat, whether you have been exposed to harmful chemicals or infectious diseases, and how much you exercise? Both certainly play a role, but we don't yet know which has a more powerful influence.

­Genes are powerful predictors of health and longevity as well as disease and death, but they're only part of the story. If your parents and grandparents lived well into their nineties, chances are you will, too -- but not if you abuse your body along the way. (Scientists say all genetic bets are off once you've made it to age 80, however. After that, family history has little bearing on longevity.)

And if your father died young of a heart attack or your mother had breast cancer, you may be genetically predisposed to those diseases. Scientists on the Human Genome Project are continually discovering more genetic determinants of chronic and fatal diseases.

While genes partially determine who will develop chronic conditions that hasten the aging process, such as cancer and heart disease, there is no question that a healthy lifestyle is your weapon against the genes you've been dealt, or your ace in the hole if you've got good genes.

A man whose father and brothers died from heart disease in their forties and fifties may very well escape the same fate by exercising regularly and keeping his blood cholesterol levels and body weight in check. On the other hand, a man with no genetic predisposition to heart disease can certainly create heart problems by eating a high fat, artery-clogging diet and leading an entirely sedentary lifestyle.

Healthy living delays many of the body changes that aging brings. And it's never too late to start on the road to better health. Eating a nutritious diet goes a long way toward insuring good health. For instance, getting enough calcium and vitamin D at any age will retard the onset, and the progression, of osteoporosis, a bone disease that causes pain, fractures, hospitalization, and even death in the elderly.

If you're a smoker and you quit at any time, you decrease the chances of having a heart attack. And exercising or becoming more physically active improves lung function and lowers the risk for heart attack, no matter how old you are.

So what changes do your cells, tissues and body systems go through as you age? On the next page, we'll the biological process of aging.