How Long a Life Is Enough Life?

Humans have long been troubled by the prospect of old age and its culmination in death. Whether to rebel against or accept this fate have been wrestled with down through the centuries. But new medical technologies and the growing science of aging have sided with rebellion. We know that aging can be pushed back and improved in its quality. That progress is well under way, but now intensified by many scientists and Silicon Valley entrepreneurs. In 2016, Mark Zuckerberg and Priscilla Chan pledged three billion dollars toward eventually "preventing, curing or managing all diseases." And some visionaries have made the elimination of death or its indefinite postponement a goal. To put those aspirations in a broader context, it is helpful to keep in mind where population growth and aging trends stand. Apart from any success in the explicit efforts to increase longevity, there will be a steady increase in the number of elderly worldwide-and a much higher percentage of the elderly as part of the overall population. Most of the largest changes will be in developing countries. They will be overburdened by the death of the elderly from expensive chronic diseases-already a vexing problem for affluent countries.