Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

People will complain about anything, and in 2001 George W. Bush appointed a President’s Council on Bioethics to deal with the looming threat of biomedical advances that promise longer and healthier lives.¹⁶ Its chairman, the physician and public intellectual Leon Kass, decreed that “the desire to prolong youthfulness is an expression of a childish and narcissistic wish incompatible with a devotion to posterity,” and that the years that would be added to other people’s lives were not worth living (“Would professional tennis players really enjoy playing 25 percent more games of tennis?” he asks). Most people would rather decide that for themselves, and even if he is right that “mortality makes life matter,” longevity is not the same as immortality.¹⁷ But the fact that experts’ assertions about maximum possible life expectancy have repeatedly been shattered (on average five years after they were published) raises the question of whether longevity will increase indefinitely and someday slip the surly bonds of mortality entirely.¹⁸ Should we worry about a world of stodgy multicentenarians who will resist the innovations of ninety-something upstarts and perhaps ban the begetting of pesky children altogether?

A number of Silicon Valley visionaries are trying to bring that world closer.¹⁹ They have funded research institutes which aim not to chip away at mortality one disease at a time but to reverse-engineer the aging process itself and upgrade our cellular hardware to a version without that bug. The result, they hope, will be an increase in the human life span of fifty, a hundred, even a thousand years. In his 2006 bestseller The Singularity Is Near, the inventor Ray Kurzweil forecasts that those of us who make it to 2045 will live forever, thanks to advances in genetics, nanotechnology (such as nanobots that will course through our bloodstream and repair our bodies from the inside), and artificial intelligence, which will not just figure out how to do all this but recursively improve its own intelligence without limit.

To readers of medical newsletters and other hypochondriacs, the prospects for immortality look rather different. We certainly find incremental improvements to celebrate, such as a decline in the death rate from cancer over the past twenty-five years of around a percentage point a year, saving a million lives in the United States alone.²⁰ But we also are regularly disappointed by miracle drugs that work no better than the placebo, treatments with side effects worse than the disease, and trumpeted benefits that wash out in the meta-analysis. Medical progress today is more Sisyphus than Singularity.

Lacking the gift of prophecy, no one can say whether scientists will ever find a cure for mortality. But evolution and entropy make it unlikely. Senescence is baked into our genome at every level of organization, because natural selection favors genes that make us vigorous when we are young over those that make us live as long as possible. That bias is built in because of the asymmetry of time: there is a nonzero probability at any moment that we will be felled by an unpreventable accident like a lightning strike or landslide, making the advantage of any costly longevity gene moot. Biologists would have to reprogram thousands of genes or molecular pathways, each with a small and uncertain effect on longevity, to launch the leap to immortality.²¹

And even if we were fitted with perfectly tuned biological hardware, the march of entropy would degrade it. As the physicist Peter Hoffman points out, “Life pits biology against physics in mortal combat.” Violently thrashing molecules constantly collide with the machinery of our cells, including the very machinery that staves off entropy by correcting errors and repairing damage. As damage to the various damage-control systems accumulates, the risk of collapse increases exponentially, sooner or later swamping whatever protections biomedical science has given us against constant risks like cancer and organ failure.²²

In my view the best projection of the outcome of our multicentury war on death is Stein’s Law—“Things that can’t go on forever don’t”—as amended by Davies’s Corollary—“Things that can’t go on forever can go on much longer than you think.”

CHAPTER 6HEALTH