In Jonathan Swift's "Gulliver's Travels," Gulliver encounters a small group of immortals, the struldbrugs. "Those excellent struldbrugs," exclaims Gulliver, "who, being born exempt from that universal calamity of human nature, have their minds free and disengaged, without the weight and depression of spirits caused by the continual apprehensions of death!"
But the fate of these immortals wasn't so simple, as Swift goes on to report. They were still subject to aging and disease, so that by 80, they were "opinionative, peevish, covetous, morose, vain, talkative," as well as "incapable of friendship, and dead to all natural affection, which never descended below their grandchildren." At 90, they lost their teeth and hair and couldn't carry on conversations.
For as long as human beings have searched for the fountain of youth, they have also feared the consequences of extended life. Today we are on the cusp of a revolution that may finally resolve that tension: Advances in medicine an...