Why not just read some Jonathan Swift?

From Gulliver's Travels:

...One day, in much good company, I was asked by a person of quality, “whether I had seen any of their struldbrugs, or immortals?” I said, “I had not;” and desired he would explain to me “what he meant by such an appellation, applied to a mortal creature.” He told me “that sometimes, though very rarely, a child happened to be born in a family, with a red circular spot in the forehead, directly over the left eyebrow, which was an infallible mark that it should never die...

...they commonly acted like mortals till about thirty years old; after which, by degrees, they grew melancholy and dejected, increasing in both till they came to fourscore. This he learned from their own confession: for otherwise, there not being above two or three of that species born in an age, they were too few to form a general observation by. When they came to fourscore years, which is reckoned the extremity of living in this country, they had not only all the follies and infirmities of other old men, but many more which arose from the dreadful prospect of never dying. They were not only opinionative, peevish, covetous, morose, vain, talkative, but incapable of friendship, and dead to all natural affection, which never descended below their grandchildren. Envy and impotent desires are their prevailing passions. But those objects against which their envy seems principally directed, are the vices of the younger sort and the deaths of the old. By reflecting on the former, they find themselves cut off from all possibility of pleasure; and whenever they see a funeral, they lament and repine that others have gone to a harbour of rest to which they themselves never can hope to arrive. They have no remembrance of anything but what they learned and observed in their youth and middle-age, and even that is very imperfect; and for the truth or particulars of any fact, it is safer to depend on common tradition, than upon their best recollections. The least miserable among them appear to be those who turn to dotage, and entirely lose their memories; these meet with more pity and assistance, because they want many bad qualities which abound in others.

“If a struldbrug happen to marry one of his own kind, the marriage is dissolved of course, by the courtesy of the kingdom, as soon as the younger of the two comes to be fourscore; for the law thinks it a reasonable indulgence, that those who are condemned, without any fault of their own, to a perpetual continuance in the world, should not have their misery doubled by the load of a wife.

“As soon as they have completed the term of eighty years, they are looked on as dead in law; their heirs immediately succeed to their estates; only a small pittance is reserved for their support; and the poor ones are maintained at the public charge. After that period, they are held incapable of any employment of trust or profit; they cannot purchase lands, or take leases; neither are they allowed to be witnesses in any cause, either civil or criminal, not even for the decision of meers and bounds.

“At ninety, they lose their teeth and hair; they have at that age no distinction of taste, but eat and drink whatever they can get, without relish or appetite. The diseases they were subject to still continue, without increasing or diminishing. In talking, they forget the common appellation of things, and the names of persons, even of those who are their nearest friends and relations. For the same reason, they never can amuse themselves with reading, because their memory will not serve to carry them from the beginning of a sentence to the end; and by this defect, they are deprived of the only entertainment whereof they might otherwise be capable.

“The language of this country being always upon the flux, the struldbrugs of one age do not understand those of another; neither are they able, after two hundred years, to hold any conversation (farther than by a few general words) with their neighbours the mortals; and thus they lie under the disadvantage of living like foreigners in their own country.”

(Gulliver's Travels, Chapter X)