Flesh Everlasting? Life Extension and Cryonics

 

Except for a few who are very old, chronically ill, depressed, or a combination, everybody hopes to wake up tomorrow morning. Most of us expect it. Montaigne generalized that no man is "so old and decrepit, who . . . does not think he has yet twenty good years to come." Twenty years would put me close to the century mark, when everybody's disabled. So far, I'm still doing most things I've always done, if more slowly. Mowing my lawn became a personal benchmark when a colleague praised my father for doing it around 1980. He was younger than I am now, and I keep pushing my mower, pedaling my bike, and bedding to my wife. Life goes on one day at a time. Unlike Montaigne's everyman, I don't expect twenty good years, but I keep on believing that healthy habits and good medical care will extend my life indefinitely, if finitely.

        There is a limit.

Life extension may contribute to the American habit of denying death and the decline in religions that promise eternal life. Back in the 20th century, we learned to take life extension for granted. Life expectancy has doubled since 1900, but much of this is irrelevant to anybody over thirteen because it reflects decreases in infant death and childhood disease. Average 30-year lifespans in the past don't express human biology any more than the abundance of children in historic graveyards proves that our ancestors were three feet tall. Even thousands of years ago, an adult of comfortable status could hope to survive into old age. Greek poets, philosophers, and politicians two thousand years ago had an average lifespan of over seventy years (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2625386/). Octogenarians were rarer in the past, but have always been around. The best predictor of personal life expectancy, besides current health, is how long you've managed to live so far--in the case of the ancient Greeks, that would be long enough to become famous.

A "Table of Mortality Based on American Experience" in 1896 (from The Mechanical Arts Simplified by D. B. Dixon and Thomas Grier) makes the pattern clear. A 10-year-old in the 1890s could expect to live to 58, far better than a newborn, but a 75-year-old could expect to hit 81, an 81-year old 84, and so forth, until the chart ends at 95. Even back then, nonagenarians happened. But I recall black-and-white movies where businessmen still in their fifties pass the torch to their sons. Even if things have changed since then, a 75-year-old today can expect just ten years of life, a modest four-year increase since Queen Victoria. Increases in life expectancy work mostly by preserving young people. At the top end, we're hitting a wall. A 110-year-old has an expectancy of one year in a nursing home. With extremely rare and decrepit exceptions, even a child can look around and know that everybody she sees will be dead in a hundred years. 

A recent study in published in Nature Communications examined structural limits in human body that refute any dream of physical immortality through improved medicine. The study measured cellular markers in the blood that increase with age and calculated that the daily stresses of staying alive become fatal, even under ideal conditions, between 120 and 150 years of age. "We conclude that the criticality resulting in the end of life is an intrinsic biological property of an organism that is independent of stress factors and signifies a fundamental or absolute limit of human lifespan" (https://www.nature.com/articles/s41467-021-23014-1). This "absolute limit" assumes all sorts of medical interventions, tubes, pumps, and whatnot, a point at which life might long ago have ceased to be worth living.

Degenerating blood cells aren't the only markers of failing viability. DNA strands in each of the sixteen trillion cells in a typical human body routinely break and need repair by enzymes, but inevitable imperfections in the repair process accumulate over life, so that age can be estimated simply by looking at the skin. Then there are mutations--the results of exposure to radiation, chemicals, and viruses--genetic flaws that can't be repaired and cause a cell either to die or to replicate abnormally. Our cells are mechanically unsound and are kept running like an old car only by constant repairs. This is evident in genetic diseases that slow the repair process and cause premature death with symptoms of aging. Medical interventions can address larger events, but the sands of time slip through an hourglass inside the DNA of every cell.

Even if chromosomes don't break or mutate, our cells eventually die off when they run out of telomeres, the tiny protective caps at the ends of chromosomes. Another way to describe telomeres is as margins to the paper in a copier that aligns imperfectly, so that after forty or so sequential copies, essential information is lost. This is called the Hayflick Limit after Leonard Hayflick, who discovered in 1961 that fetal cells, previously thought to be immortal if kept in the right medium, stopped replicating themselves and died after 40-60 replications. There is good news and bad news here. An enzyme called telomerase can extend telomeres, making body cells potentially immortal, but it occurs naturally in cancer cells and is the reason for their lethal overgrowth. So Hayflick's limit has an important function, the pruning of mutant cells. Indeed, a treatment for cancer is to suppress the telomerase so that cancer cells die at the limit. You can buy supplements advertised to stimulate telomerase, but, if they work, there is risk of cancer, much as rejuvenating testosterone supplements increase the risk of prostate disease.

Beyond these,  other degradations accumulate with time. Arteries clog with plaque as surely as valleys fill with silt and streams erode hillsides. Cartilage wears away in the joints. Heavy metals and toxic chemicals accumulate. Teeth decay. Some of this is repaired, but repairs are inevitably imperfect. Senescence, a scientific word for failure to rejuvenate, is an essential part of nearly all species that reproduce sexually. The individual is disposable after producing offspring. Many primitive species, such as bacteria, divide symmetrically without limits, one immortal organism in many bodies, and a few plants such as the sequoia tree never grow old, but only die when killed by accidents such as fire or drought. They are immortal in the sense of J. R. R. Tolkien's elves, so there is no absolute theoretical necessity for physical aging, but aging is programmed into many overlapping aspects our bodies.

            The only remotely plausible current prospect for widespread good health past the age of 110 would be by re-engineering the body at a molecular level using nanotechnology. This fantasy imagines gnat-like nanobots swarming down veins, working through cell walls to restore telomeres while killing cancers and pathogens and repairing DNA, fixing whatever ails us. These wouldn't be robots in the metallic sense, but designer molecules compounded like natural enzymes. Recent breakthroughs in miniaturization feed this fantasy. Last year, a physician threaded a tiny camera through my arteries by a buttonhole slit in my groin, propping open several near-occlusions with tiny sleeves called stents. With luck, this futuristic operation, now routine, may buy me a decade before I become a cliche by dying of heart disease. But this technology is clunky compared to the rejuvenation that futurists imagine.

A few people with faith in future scientific miracles are paying to have their bodies frozen in the hope that future doctors will thaw and cure them. My stage comedy on the subject, Immortality Inc, involves a middle-aged veterinarian. Frank, whose wife, Lilly, has a congenital heart problem and becomes obsessed with having her body cryogenically preserved. When her terrier dies, Lilly brings it to Frank's office in an ice chest, begging him to have it frozen so the three of them "can be together in the Star Trek time." Frank objects to the cost, sending his wife into fatal hysterics. Guilt forces Frank to honor her wishes and freeze her, and his New Age assistant, Gaia, falls in love with Dick, the technician from Resurrection Inc who comes to do the freezing. Meanwhile, Frank, though a dutiful husband, is in love Lilly's sister Rose, an Egyptologist and museum curator. Even though Rose has always liked Frank, his frozen wife stands between them. Then Resurrection Inc, a nonprofit, faces bankruptcy, threatening to defrost Lilly. But, in happy ending, the four join its governing board, Lily's ghost sets Frank free, and Dick uses spam to launch a lucrative cult with Lily as the First Frozen with Gaea as her priestess. The play ends with a hymn sung before an ancient mummy and Lily's gleaming tank:

All hail to the First Frozen!

You showed us all the way

To bathe in liquid nitrogen 

And save our DNA.

I began Resurrection Inc as a "comedy of ideas" to satirize desperate solutions to the problem of death, not just cryogenics. Gaea embodies New Age. Frank is a skeptic, Rose a Methodist, Dick a pragmatist. But the cryogenic dream is a fitting centerpiece, the ultimate Hail Mary pass to everlasting life. Literally praying Hail Mary might be more plausible because it is, at least, a simple process even if there's no physical mechanism behind it. The cryogenic dream hangs on a long chain of improbabilities, and a break of any one link would defeat it. It's easy to imagine the dream realized, a happy sequence of events, and I confess to a sense almost of bereavement when I read of a glassy corpse dumped from its liquid nitrogen tank into a grave, but an astonishing number of windows would have to align for Lilly to be resurrected.

Even though people have been resuscitated after being clinically dead in near-freezing water, they were not actually frozen. Freezing causes tissue damage from sharp ice crystals, and replacing the blood with fluid that does not crystalize is fatal. Any attempt to revive a frozen body would involve, at least, thawing it and replacing the antifreeze with blood before brain damage set in. Even if this were possible, because it is illegal to freeze a living person, future physicians would still have to reverse a cause of death. Even then, life-extension would be modest unless it was followed by massive rejuvenation processes, and all of this in a future near enough to ferry the corpse in a tank of liquid nitrogen kept cold by decades of paid-up electric bills.

Even if Star Trek science is realized, there are economic limitations. The life expectancy of a corporation on the S&P 500 is about 18 years, and a corpse will stay frozen only as long as its sponsoring corporation survives the vagaries of inflation, investment, mismanagement, malfeasance, and hostile takeovers. Even if Lilly's body miraculously exists in glass-hard condition a century from now and techniques have emerged for reviving frozen old women, why would anybody spend hard cash reviving Lilly? She's nobody's ancestor. Nobody's bothered if she stays dead. If any of Frank's endowment miraculously remains, the living will presumably find better uses for it. If the 22nd century needs people, they can clone specimens healthier than Lilly, or just have old-fashioned sex.

           The great weakness at the heart of cryonics is its vanity, the assumption that, because my life (out of 7.8 billions) is so precious to me, it ought to be valuable to strangers in the distant future. I imagine that my death is extraordinary even though it's only one out of 150 thousand that happen every day. The dream or illusion that death is a bad and something ought to be done about it lurks behind all proposed solutions from Jesus Christ to the Life Extension Foundation.