CAMBRIDGE – Humans have long sought the elixir of youth, so it is not surprising that even non-scientists closely follow the latest research into aging. But is what most people consider simply a fact of life actually a "disease” that can be cured? Or is there some insurmountable limit to the lifespan of human bodies?
Of course, almost everyone would welcome an extension of their healthy lifespan, and some scientists are looking at increasingly extreme ways to achieve that. Yet if we could stay alive only with the help of extreme measures, many of us would opt instead for non-resuscitation and solely palliative treatment. We might also find comfort in having the option of "assisted dying” as soon as our quality of life and our prognosis dipped below a certain threshold. Moreover, a huge increase in life expectancy could have undesirable and far-reaching consequences for society as a whole.
Much serious research into aging now focuses on stretches of DNA called telomeres that shorten as people age. By adjusting the telomeres of nematode worms, for example, scientists have managed to increase the lifespan of these creatures tenfold, although the same approach has less effect on more complex animals. The only effective way to extend the life of rats is to give them a near-starvation diet. But the naked mole rat may have some special biological lessons for us; some of them live more than 30 years – several times longer than the lifespan of other small mammals.
Any major breakthrough in extending human life would drastically alter population projections. The social effects, while obviously huge, would depend on whether the years of senility were prolonged, too; whether women’s age at menopause would increase; and how families would be structured if many generations were alive at the same time. Expensive treatments to extend human lives could also have implications for inequality; as in many other areas of technology, the wealthy would be most able to afford such services.
The powerful desire for a longer lifespan creates a ready market for exotic therapies of untested efficacy. For example, Ambrosia, a US start-up founded in 2016, has been offering Silicon Valley executives a transfusion of "young blood,” although the company halted the treatment earlier this year following a warning from US regulators. Another recent life-extending craze was metformin, a drug intended to treat diabetes, but which some claim can stave off dementia and cancer in otherwise healthy people.
More credibly, human-genome analysis by US company 23andMe has yielded interesting insights into our vulnerability to some diseases, as well as regarding our ancestry. And Craig Venter, a pioneer in mapping the human genome, aims to analyze the genomes of the thousands of species of bacteria in our gut – an internal ecosystem that may very well be crucial to our health.
The longing for eternal youth in Silicon Valley stems not only from the immense wealth of its leading lights, but also from a culture that regards those above the age of 30 as over the hill. The futurist Ray Kurzweil hopes for a metaphorical "escape velocity,” when medicine advances so fast that life expectancy increases by more than a year each year, offering the prospect of immortality. Or perhaps computers will become so advanced that we will be able to download our brains into an electronic simulacrum, and perpetuate our consciousness and memories that way.
But hardcore longevity enthusiasts worry that "escape velocity” may not be reached within their expected natural lifetime, and therefore want their bodies frozen from the moment they die until immortality is possible. Not so long ago, three academics in the United Kingdom (though not, I’m glad to say, from Cambridge, my university) signed up to have their dead bodies’ blood replaced with liquid nitrogen. One went all-in with the Michigan-based Cryonics Institute, while two took the lower-price option of having an Arizona-based company called Alcor freeze just their heads. The three accept that the chance of resurrection is small, but point out that it would be zero otherwise.
I find it hard to take this aspiration seriously, and I would rather end my days in an English churchyard than an American freezer. And I don’t think it would be good if cryonics ever did succeed. Let’s suppose Alcor stays in business and dutifully cares for its cryogenically frozen bodies for the requisite number of centuries. The corpses would then be revived in a world where they would be strangers – refugees from the past.
Perhaps they would be treated indulgently, as most people believe distressed asylum seekers or displaced Amazonian tribespeople should be treated today. The difference, however, is that the thawed-out corpses would be burdening future generations by choice, so it is not clear how much consideration they would deserve.
The prospect of human immortality has long been the stuff of science fiction. The world will be a better place if it remains so.
Copyright: Project Syndicate.