Must Aging Presuppose Deterioration?
There’s nothing in biology that prevents
longer life – at least in theory.
Aging and death are aspects of human existence we learn about in childhood and grow to accept, begrudgingly. That is not likely to change soon. But must it be that way? Suppose that a car manufacturer invented a car with internal know-how to gather up materials from the environment and incorporate them into any part that failed, and replace any part that had excessive wear and tear. Even under the 2nd Law of Thermodynamics, the car could work indefinitely.
Living organisms are like that. They eat, obtaining material from their surroundings. They repair DNA in their cells. They heal wounds. Some animals can regrow limbs; plants are able to re-sprout new branches and leaves for decades. Most cells in the human body have been replaced several times throughout life. So why do we age? Why does everything give up at some point?
If the know-how is internal to the organism, there shouldn’t be limits to lifetime, because “know-how” (whether supervised or programmed) can overcome the restraints of the Second Law. Given an abundance of external material, the right know-how could incorporate energy from the surroundings and convert it into useful work.
Theoretically, you could have a perpetual motion machine if there was a mind—like an immortal angel or someone—having the desire and power to keep it running in spite of increasing entropy. Internal software might also be able to achieve it. This is the basis for sci-fi speculations about transhumanism, wherein robotic life could travel across space, land on any planet and reproduce, if it had the know-how to do it. Until the impending “heat death” of the universe began to deplete available materials, know-how would be virtually eternal.
Keep these theoretical notions in mind as we look at news items about aging. Maybe our proverbial “three score and ten” is not inevitable.
Centenarians consistently present a younger epigenetic age than their chronological age with four epigenetic clocks based on a small number of CpG sites (Aging News, Impact Journals, 17 Oct 2022). The press release begins,
Aging is a progressive time-dependent biological process affecting differentially individuals, who can sometimes present exceptional longevity. Epigenetic alterations are one of the hallmarks of aging, which comprise the epigenetic drift and clock at DNA methylation level.
The researchers looked at the “epigenetic clocks” in French individuals who lived to age 100 or more. Specifically, they evaluated methyl marks at four CpG sites. CpG sites are portions of the genome where a “C” base (cytosine) is followed by a “G” base (guanine). The results revealed an unexpected thing: in the epigenetic clocks of these centenarians: their “epigenetic age” (DNAmage, or DNA methylation age) was younger than their chronological age. They explain:
These differences suggest that epigenetic aging and potentially biological aging are slowed in exceptionally long-lived individuals and that epigenetic clocks based on a small number of CpGs are sufficient to reveal alterations of the global epigenetic clock.
“This suggests a decelerated epigenetic and biological aging in these two groups of individuals, confirming the results of three other studies performed on Italian, Australian and Israeli long-lived individuals. In addition, our study also demonstrated the possibility of using epigenetic clocks based on a small number of CpG sites to reveal DNAmage and chronological age differences between individuals with different life expectancy.”
So why aren’t the epigenetic clocks slowed in everybody? Could they have been? Can we reset those clocks with treatment?
DNA clocks suggest ageing is pre-programmed in our cells (New Scientist, 15 Sept 2022). This article by Michael LePage suggests that our epigenetic clocks wind down and cannot keep going indefinitely. We know that our pet dogs and cats don’t live as long as us; each animal has its own life expectancy. According to UCLA, that lifespan appears built-in; it is not merely a consequence of deterioration.
The team involved says the fact that all mammals seem to have the same “ageing clocks” shows that ageing is the result of developmental programs that have been retained during the evolution of mammals, rather than being solely due to accumulating damage.
A question could be asked, though, whether it has to be that way. If aging is not due to damage accumulation, could developmental programs be upgraded with different countdown settings? What’s evolution got to do with it?
Transplanted livers can keep working for a total of over 100 years (New Scientist, 16 Oct 2022). What do livers do? They live. That’s why they’re called livers, isn’t it? Some of them can live for a long time.
Here was a surprise coming out of work at the University of Texas Southwestern Medical Center: livers transplanted from older donors sometimes lasted longer than those from younger donors. How could that be? Were the senior livers getting better over time? Looking at the stats from 253,406 liver transplants from 1990 to the present, Christine Hwang and her colleagues experienced a “wow” moment:
The team found that 25 livers had lasted for at least 100 years across both the donor and recipients’ bodies, with 14 still remaining in their recipients. The oldest liver was aged 108.
“The wow-factor to this study is having 25 patients with [100-year-old] livers,” says Kadakia.
“We do not know of any other types of organ transplants that have lasted 100 years,” says Hwang.
The liver was outlasting the rest of the body. Some of the long-living livers had been donated by those who were already pretty old.
People who donated livers that reached the age of 100 were aged 84 when they died, on average, while those who donated livers that failed to survive for 100 years had an average age of 38 when they passed away. This provides evidence that older donors can sometimes provide more successful liver transplants than younger donors.
What this implies is that seniors should not hesitate to sign up as liver donors, and patients should not hesitate at getting a senior’s liver in a transplant operation.
“Studying these livers that made it to age 100 could reveal new biomarkers that are important for liver lifespan,” says Kadakia. “Manipulating such markers in livers before transplantation could help us improve the outcome.”
If biomarkers could be manipulated by intelligent surgeons to make a liver last longer, what prevents the body’s own internal mechanisms from doing that?
It’s a shame that the rest of the body goes kaput before the liver does, but that reveals something about the aging process. An organ doesn’t have to be viewed as necessarily undergoing progressive degeneration. If a liver can maintain its vigor for 84 years, and keep working well for decades more in another body, it is not necessarily the limiting factor in aging. The liver, while maintaining many vital processes in the rest of the body, is somehow being maintained itself beyond the normal lifespan of its user.
Is aging and death inevitable? Is it part of the world order that must be endured?
At the beginning of the Bible, there was a Tree of Life in Eden; perhaps it had something to do with maintaining physical needs to prevent deterioration. But even after death entered the world through sin (Genesis 3, Romans 5), humans lived for centuries before the Flood (969 years for Methusaleh, the world record). After the Flood, lifespans dropped. In medieval times, average life expectancy had dropped as low as 33 years. Now with modern medicine it is on the rise again. Still, though, centenarians comprise less than 1% of the human population, although that percentage appears to be rising.
Near the end of the Bible, in the Millennium (Revelation 20), long life will be the norm. Isaiah said that one dying at 100 will be thought of as young (Isaiah 65:17-25). And in the eternal state described in Revelation 21-22, death will be banished forever among the inhabitants of the new heavens and new earth. God “will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away” (Revelation 21:4). Notably, the Tree of Life reappears in the New Jerusalem “for the healing of the nations.”
Death is an enemy, an intruder into perfect world God designed. Our Creator promised a Deliverer from death right after Adam and Eve sinned. God told the serpent (Satan) who had lied to the first human couple, “I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel” (Genesis 3:15). The serpent did bruise the “heel” of the offspring of the woman—the virgin-born Messiah, Jesus Christ, the Son of God. His death on the cross for the forgiveness of sins fulfilled that part of the promise. Satan’s evil plan for world domination of mankind was defeated at the cross. His final defeat—the crushing of the serpent’s head—comes at the last judgment (Revelation 20).
Modern medicine may increase human lifespans slowly as more is learned about aging, but in this era of human history, death is a certainty till Christ returns. The death of the body, however, does not mean the death of the soul. “For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord” (Romans 6:23). We can “take hold” of that eternal life by trusting in Jesus.