Numerous efforts have been made to comprehend the “how” and “why” behind aging, with scientists identifying over 300 potential explanations. Though no definitive answers have been found to these questions, the various theories can be categorized into two main schools of thought: the gradual accumulation of damage over time and the concept of genetic programming.
The first school of thought suggests that our bodies are persistently assaulted by our environment, leading to cumulative damage over the years. This damage impacts our DNA and cells, causing them to deteriorate and undermining the essential components crucial for our survival. For example, wrinkling is a sign frequently linked with aging. After the age of 20, our skin produces 1% less collagen annually, causing it to become increasingly fragile. However, the primary culprit behind skin wrinkling is UV radiation from the sun, accounting for 80% of the wrinkles we develop over time.
The second set of theories suggests that aging is determined by our genetic makeup, directed by an intrinsic molecular timer unique to each species. In essence, we age because nature doesn’t prioritize keeping our bodies in flawless condition. The primary goal is to maintain our reproductive capabilities for an optimal duration, after which our bodies are allowed to decline. Evidence backing this notion emerges from animal research, where scientists have managed to extend the lifespan of certain animals by modifying just a single gene.
Aging is, simply and clearly, the accumulation of damage in the body. That’s all that aging is.
The pace of aging in humans and other mammals could be influenced by how rapidly they must reproduce before other factors lead to their demise. Generally speaking, the smaller the creature and the more hostile its environment, the shorter its lifespan. A field mouse, for instance, has to reproduce before becoming prey to a hawk, meaning its organs and immune system don’t require longevity beyond a brief span of time. Conversely, elephants, facing fewer threats, have bodies that are built to endure for many decades.
Similar patterns of aging are observed in other mammals, such as the chimpanzee, but as we examine different species, diverse patterns begin to emerge. In the cases of the desert tortoise and the white mangrove tree, the risk of death is notably higher during their younger years, with the mortality rate decreasing as they grow older.
The hydra, a tiny freshwater organism capable of ceaselessly renewing its cells, presents an even more fascinating case. Its mortality and fertility rates remain steady for centuries, exhibiting no evident signs of biological or physical aging. Although this creature has captured our attention, scientists are still a long way from understanding what parts of it could be used to help slow down how humans age.
I believe that aging is a disease. I believe it is treatable. I believe we can treat it within our lifetimes. And in doing so, I believe, everything we know about human health will be fundamentally changed.
Aging starts within the body’s tiniest parts, the cells. The reasons and ways cells age are still debated, but some processes are becoming understood. Back in the early 1960s, biologist Leonard Hayflick found that cultured cells would only divide about 50 times before stopping. This number has become known as the Hayflick limit. Except for stem cells and cancer cells, this limit is true for all human tissues, though cells from older people tend to divide even fewer times.
What causes cells to slow down and eventually die? An intriguing answer lies in the discovery of telomeres. Telomeres are like the plastic tips on shoelaces, but they are at the ends of chromosomes, the parts of our cells that carry our genes. They act like protective caps, guarding chromosomes from damage. When a cell in our body splits, a little part of the telomere gets used up. So, the more times this happens, and the older we become, the shorter these protective parts get. When the telomere becomes short enough, cell division comes to a complete halt.
Targeting short telomeres might seem like a clear focus for anti-aging efforts, but having very long telomeres or more of the enzyme telomerase, which helps keep telomeres long, isn’t necessarily a good thing. Cancer cells can take advantage of telomerase to grow without control. Also, individuals with unusually long telomeres might have a higher risk of developing lung cancer and brain tumors.
Only 20 percent of our longevity is genetically determined. The rest is what we do, how we live our lives and increasingly the molecules that we take.
Despite the complexities of aging, researchers have proposed some ways to possibly extend lifespan. One of the most well-known methods is moderate reduction in calorie intake. In one study, individuals who consumed 15 percent fewer calories over a span of two years showed a noticeable decrease in their base metabolic rate. This reduction is seen as a sign that their bodies aged more slowly.
Words of wisdom
“Early to bed and early to rise makes a man healthy, wealthy and wise.” —Benjamin Franklin
“The first wealth is health.” —Ralph Waldo Emerson
“The greatest of follies is to sacrifice health for any other kind of happiness.” —Arthur Schopenhauer
“The quality, not the longevity, of one’s life is what is important.” —Martin Luther King, Jr.