Forget about seeing into the distant future, what about existing long enough to actually live it? The quest for immortality is a beguiling theme in human culture, and it is no surprise to see why the concept of living forever, for better or for worse, has been popularized throughout history. To have the opportunity to watch time unfold with your own eyes is something that dwells in the depths of many people’s thoughts, for a variety of reasons. However, people accept that they will never see their twentieth generation grandchildren, or witness the types of technological breakthroughs we only dream about in science fiction media. Granted, it is a fact that human lifespan has been extended significantly with the advent of modern medical and hygienic practices, but it seems that we as a species have reached the upper limits of how much time we are allotted on this planet. Or have we?
There are countless organisms with extremely long lives that inhabit the earth. Tortoises, elephants and whales are all examples of animals that have existed for decades beyond that of many other organisms on this planet. But impressive lifespan is not limited to large animals; many smaller species exist that hold equal footing with their larger counterparts. In fact, one of these, T. nutricula, is a species of jellyfish that undergoes a “biological immortality” in which they revert to a sexually juvenile stage in response to environmental stress, essentially resetting their internal aging clock. In principle, these jellyfish could live indefinitely, barring infectious disease or traumatic injury.
Where humans are concerned, however, current medical research has taken a more pragmatic view in that it is focused more on improving quality of life as human beings get older, as opposed to finding a way to prevent or reverse aging. Encouraging clues from human centenarians who display a vibrancy of personality and cognitive function at an extremely advanced age provide scientists with ideas for dietary and lifestyle variables that may eventually be used as part of a template for longevity that identifies a suite of common features that may be key to extending human lifespan. Presently, there seem to be two factors that consistently contribute in this regard: lifestyle and genetic background.
Lifestyle is important in that it allows a measure of control over environmental factors that can potentially affect lifespan. Aside from the general admonitions regarding a sedentary lifestyle, as well as employing a modest degree of common sense associated with avoiding actions that would earn one a Darwin award, it appears that dietary regulation, specifically caloric restriction, significantly increases lifespan in laboratory animals. In numerous studies, animals fed a diet fine-tuned to control caloric content had longer lives than their calorically unrestricted counterparts. While this demonstrates a working physiological effect in the lab, application in daily human living may be more of a challenge, as the degrees of caloric restriction employed in laboratory conditions are not necessarily levels broadly agreeable with a high quality of human living.
On a more molecular level, the concept of telomere attrition has been known to geneticists for decades and describes a process by which specific bits of DNA called telomeres erode over the years, leading to a cumulative loss of genetic material that correlates with aging. Studying the mechanisms that regulate telomere degradation reveals that molecules involved in telomere preservation are closely intertwined with cancer signaling, however, demonstrating that the genetic solution to aging may not be as simple as flicking a molecular switch.
So is the key to prolonging individual existence hidden within our genetic structure, which can be unlocked with continued research? Or perhaps an unanticipated dietary component with unique anti-aging properties is just waiting to be found? It’s likely that the actual solution will be a combination of the two, as it seems that nature and nurture play equally important roles in determining how much corporeal time a person (or any organism, for that matter) has on this planet.
In this continuum of human existence, perhaps the definition of “immortal” includes a state of being beyond just our physical body. By that definition, we are already eternal entities, living the first part of our existence in these bodies, on this planet. As for what comes after? We can only wait and see. Regardless of where such thoughts lead, the concept of immortality will continue to inspire scientists and philosophers alike as the answers to the questions surrounding this concept are sought out and discovered.