It’s a fact of life—every living thing ages. Aging is defined as growing older, developing or maturing. The aging process involves progressive changes in the body’s ability to generate, produce and replace healthy cells. Over time, aging affects every cell in every organ, structure and tissue in the body. The aging process varies a great deal from person to person and there isn’t an accurate way to determine or measure the rate or degree of aging.

Older Man and Woman Image

As children, adolescents, and even 20-somethings, we seldom give much thought to growing old. However, at some point during our 30s, 40s or 50s, most of us begin to see—and feel—the effects of middle age. These decades often bring on cosmetic changes, such as a few (and maybe more than a few!) wrinkles and gray hairs, and some degree of physical decline—aches and pains of arthritis that we never noticed before, a couple added pounds around our middle, or higher blood pressure, for example. By our 60s and 70s, most of us discover that old age has suddenly crept up on us.

It may be surprising to learn that of the many physiological effects of aging, some occur much earlier than you might think. According to the National Institute on Aging of the National Institutes of Health (NIH), beginning at about 20 years of age, lung tissue loses elasticity and muscles involved in breathing shrink—resulting in a gradual decrease in the maximum amount of air you can take in with each breath!

Although it affects every aspect of our lives—physical, physiological, mental and emotional—aging is a lifelong process and taking proper care of ourselves and making healthy lifestyle choices—at every stage of life—can go a long way towards helping us live longer and reducing our risk of disability.

People have obsessed about aging since the beginning of recorded history, but the medical community still doesn’t fully understand everything about the aging process. Researchers, scientists and medical professionals are working to find the answers to questions about aging that remain, such as:

  • Why does aging occur?
  • What triggers the aging process?
  • What are the biological processes involved in aging?
  • How do genetic (hereditary) factors, metabolism and the immune system affect aging?

The hope is that answers to these and other questions about aging will lead to more effective ways to help us live longer, healthier lives—from childhood and through our teens, 20s, 30s, 40s, 50s, 60s, 70s, 80s and beyond.

Sources: National Institute on Aging (National Institutes of Health, U.S. Department of Health & Human Services), Centers for Disease Control and Prevention (CDC) - Healthy Aging, and Taber's Cyclopedic Medical Dictionary

Publication Review By: the Editorial Staff at

Published: 15 Jun 2012

Last Modified: 09 Jan 2015