You might think that you have heard everything there is to know about how long humans can live, but even in this overworked corner of human research, there is always something new.
Over the last few decades. we have watched in awe as longevity statistics have exploded. For people in industrialized countries, life expectancy, at the beginning of the 20th century, was between 30 and 45 years, rising steadily to about 67 years by the end of the century. Life expectancy continues to rise until now, people who live to age 100 or older are the fastest growing demographic. In the past, researchers have looked to improvements in health care, nutrition, and standard of living to explain why some people live significantly longer than others. Other researchers have redirected their attention to the habits of super-centenarians, or the detection of ‘blue zone’ areas of the world in which people live to an exceptional age.
Looking for the secrets of aging in the living cell
Meanwhile an army of scientists have been investigating longevity at the cellular level. It’s here, they believe, in the study of the composition and behavior of the human cell, that they will find the causes of life and death. It now seems possible to understand the very foundation of life, and get a glimpse into the secrets of what makes humans age.
Although postponing death raises important ethical and practical questions about global overpopulation and considers the existential dilemma of immortality, the secrets of human aging is irresistible to researchers. Theories about how and why human cells age, and how we can fight it, appeal to us, and whenever new ideas emerge, we pay attention. Recently, a word new to many of us, has found its way into our consciousness.
The word is senescence, defined as the cause of death when billions of our cells stop growing, dividing and replicating themselves. The potential for the future of medicine in understanding senescence is not lost on the medical and pharmaceutical community. Dr. van Deuten of the Mayo Clinic, in an article written by Megan Forliti, makes this observation:
“Senescent cells that accumulate with aging are largely bad, do bad things to your organs and tissues, and therefore shorten your life but also the healthy phase of your life. And since you can eliminate the cells without negative side effects, it seems like therapies that will mimic our findings – or our genetic model that we used to eliminate the cells – that drugs or other compounds that can eliminate senescent cells would be useful for therapies against age-related disabilities or diseases or conditions.”
The many theories of cellular stress
Various theories exist, one idea being that telomeres, the repeated segments of DNA that occur at the end of chromosomes come to the end of their genetically programmed number of repeats, and can divide no further, causing the cell to die. There are others:
The Wear and Tear Theory, assuming that cells simply wear out. Cross-linking Theory, assuming that the structure and shape of the cells change so that they are unable to carry out their functions. Autoimmune Theory, assuming that immune reactions begin to attack cells of the individual’s own body.
There is also the Oxidative Theory, the Free Radical Theory, and the Mitochondrial Theory. This latest theory seems the most complex, and is based on the idea that a vicious cycle exists within the mitochondria (an organelle in the cytoplasm of cells, containing material and enzymes important for cell metabolism), in which:
“the mutation of mitochondrial DNA impairs the function of proteins in the organelle’s respiration machinery, thereby enhancing the production of DNA-damaging oxygen radicals, which ultimately, after several other stages, leads to tissue dysfunction and degeneration”.
And lastly, the Molecular Inflammatory Theory, which addresses age-related inflammation of tissues in the body, and has been linked to many age-associated illnesses, including cancer, cardiovascular disease, arthritis, and several other diseases.
Many of these theories have been aired in the public domain, making their way into television shows and publications, with claims that some medical treatment, some supplement or other, can fight cell damage and thereby extend longevity.
And a theory that has yet to be revealed
Because living longer, and delaying death has so much universal appeal, I wasn’t surprised to find the following notice about an emerging theory on extending the human lifespan. It was presented by Dr. George Tetz of the Human Microbiology Institute at the American Society for Microbiology in New York last summer:
“Based on Tetz’s theory and law, we propose a novel model to calculate several parameters, including the rate of aging (or the rate of reduction of the remainder of the maximum permissible level of alteration) and the remaining lifespan of individuals. We believe that this theory has great explanatory and predictive potential for the influences of diseases, medication, and medical procedures on human longevity.”
They go on to say, “We would be happy to share all the details of this theoretical concept right after its official publication (in press).” Having explored innumerable theories of cell longevity, I have an open mind, and will, as the authors suggest, await publication of Dr. Tetz’s discovery.
But, it’s important to note, just the same, that there are no known medical treatments or advancements that can affect the length of human life expectancy. Only time will tell what the future holds.
Meanwhile, if you are curious about how long you will live, and don’t mind a less scientific approach, here is a short quiz for you. Be aware, however, that the results are non-binding!
You can take the Quiz here: