Short story about a boy and girl enclosed in an experiment and given injections to age rapidly

Question

The story is told from the point of view of one of the scientists. He meets the subjects in the experiment as they play in the lab before being put into the enclosure that will become their world/home. They are given injections that cause them to age rapidly, but in their false "world" they go to school, date, marry, have a family and grow old without knowing that it is all fabricated and not real. Their bodies age past age 100, 120, 140+... The experiment is to see what will happen to human beings when they live past what they are currently capable of (105 or 110). It is sort of a quest for the fountain of youth, divine knowledge and/or immortality.

The kids grow to at least 160 or 180 years old... their heads and bodies change drastically as they continue the aging process. The last scene is of the two coupling, then the girl seems to look directly at the scientist as she stares into the camera and dies. The horror of what the scientists have done to ruin two perfectly good lives shocks them and they quietly disband the experiment.

Answer 1

This sounds like "The Time Beyond Age" from the short story collection The Bone Forest, by Robert Holdstock.

The day before the experiment was scheduled to commence, Martin and Yvonne, our two MAA-grown subjects, were allowed into the observation laboratory for the last time.

[...]

The first stages, of course, were the familiarization procedures, and our two subjects were introduced to the closed environment that was to be their home for the rest of their natural and unnatural lives. There was something almost depressing in watching the children, conceived, grown and matured to the age of six in a Morris Artificial Amnion, now facing an incarceration in a second womb, this time for good.*

[...]

A breakthrough into what was difficult to say. The kudos for the original discovery of Chronon was not ours. The chemical of age, the simple protein that accumulates in body cells at a steady rate and dictates the phenomenon of aging, was the discovery of a Swedish biochemist seven years before. The acceleration of development, and of aging, under the influence of artificially high concentrations of synthetic Chronon, was the contribution of a Scottish behaviorist at the University of Edinburgh, four years later.

[...]

The excitement of year one hundred passed into our distant past, and over the course of weeks, then months, the enormous ages reached by the subjects failed to arouse even the slightest whimper of joy. We worked virtually full-time countering the efforts of each of their bodies to shift into a disease condition.

[...]

One corner of the laboratory was filled with neatly stacked printouts representing the last fifty years of the subjects' lives, and staring at that pile of information I realized that nowhere in its bulk could I put my finger on a single statement of feeling, of awareness. Even the sheets on which were recorded the last living moments of Martin and Yvonne were bare, sterile accounts of failing physiology and murmurings and alpha waves; there would be no account of what they thought, what they felt as death unfurled its protective wings about them.

According to the Wikipedia article, it was originally published in "Supernova" in 1976.

From the Wikipedia article:

This is a science fiction short story describing a scientific experiment in which two subjects’ rate of aging is increased in an environment that is devoid of all disease. The subjects live for the equivalent of centuries and evolve into exaggerated archetypes of male and female. Eventually they die, but not before the perpetrator of the experiment self-administers the life-altering treatment.