SF short story about an attempt to colonize a planet by modifying successive generations to enable them to live on the surface’s hostile environment. The main character is a modified human but cannot live on the planet's surface. His and the other colonists children will be the first generation that can live outside the dome.
A human spaceship crashlands on a planet where conditions are inimical to human life - including a hostile sentient native species. So the humans build a large enclosure for themselves and undergo induced mutations so each succeeding generation is better adjusted to conditions on the planet than the last until finally the last generation is ready to step out of the enclosure.
More precisely, from another question (see below):
At the end of the story [...] the final generation is almost ready to be released into the wild, but they are strong (with a low, dense, non-humanoid body shape) and out of control, and risk damaging (or actually do damage) the dome and therefore the lives of the older generations.
The older generations knew very well what was going to happen; the new generation being so aggressive they would end up killing their elders. Quote snatched (again!) from user14111's answer to Story about suicidal breeding of aggressive next generation on generation ship
There was a new sound echoing through the dome. "Now they don't need us to let them out, anymore." There was a quick, sharp, deep hammering from outside—mechanical, purposeful, tireless. "That . . . that may be Donel now."
In high school I found a short story "Keep Out" by Fredric Brown, where people in a dome colony on Mars genetically alter the kids in a later generation to survive on the outside. In the end the narrator, one of the altered children, tells of how they have come to hate the unaltered humans and plan to kill them—the final line is:
This is our planet and we want no aliens. Keep off!
The story is available at Project Gutenberg.
"The Keys to December" by Roger Zelazny.
Born of man and woman, in accordance with Catform Y7 requirements, Coldworld Class, Jarry Dark was not suited for existence anywhere in the universe which had guaranteed him a niche. This was either a blessing or a curse, depending on how you looked at it. So look at it however you would, that was the story. Thus does life repay those who would serve her fully.
He and his fellow kind were bred to live on extremely cold planets, but then not sent to them as the program died. They had to live in special refrigeration cases on earth, with no plans now to send them to planets for which they were adapted. They decided to "terraform" a planet to the deep cold to which they were adapted. The number of expensive Worldchange units they could afford would take thousands of years. So they rotated in suspended animation as their new world VERY slowly changed.
The calculations, decisions, further voting, and more decisions on how any Worldchange units they could afford, and how long it would take to "terra"form follow:
"The staff also says that a hundred Worldchange units could alter it to what we want in 5-6 centuries. Will forward costs of this machinery shortly. Come live with me and be my love, in a place where there are no walls....Sanza" When the figures arrived Jarry wept icy tears. One hundred machines, capable of altering the environment of a world, plus twenty-eight thousand coldsleep bunkers, plus transportation costs for the machinery and his people, plus...Too high! He did a rapid calculation. He spoke into the speech-tube: "...Fifteen additional years is too long to wait, Pussycat. Have them figure the time-span if we were to purchase only twenty Worldchange units. Love and kisses, Jarry." During the days which followed, he stalked above his chamber, erect at first, then on all fours as his mood deepened. "Approximately three thousand years," came the reply. "May your coat be ever shiny--Sanza." "Let's put it to a vote, Greeneyes," he said.
The decision to use only twenty Worldchange units that take three thousand years to "terra"form the planet, while they rotate in and out of suspended animation sleep, becomes their action:
The vanguard arrived, decked out in refrigeration suits, installed ten Worldchange units in either hemisphere, began setting up cold-sleep bunkers in several of the larger caverns.
Although the 3,000 years of world-change forced either fast evolution or death on the native life, the "bipeds" evolved at the very edge of their ability, and still many died. The protagonist advocated for an even longer time, to give the now-"people" a chance to evolve.
"They are intelligent," he told them. "It's all in my report." "So?" asked Yan Turl. "I don't think they will be able to adapt. They have come very far, very rapidly. But I don't think they can go much further. I don't think they can make it all the way." "Are you a biologist, an ecologist, a chemist?" "No." "Then on what do you base your opinion?" "I observed them at close range for six weeks." "Then it's only a feeling you have...?" "You know there are no experts on a thing like this. It's never happened before." "Granting their intelligence--granting even that what you have said concerning their adaptability is correct--what do you suggest we do about it?" "Slow down the change. Give them a better chance. If they can't make it the rest of the way, then stop short of our goal. It's already livable here. We can adapt the rest of the way." "Slow it down? How much?" "Supposing we took another seven or eight thousand years?" "Impossible!" "Entirely!" "Too much!" "Why?" "Because everyone stands a three-month watch every two hundred fifty years. That's one year of personal time for every thousand. You're asking for too much of everyone's time." "But the life of an entire race may be at stake!" "You do not know that for certain." "No, I don't. But do you feel it is something to take a chance with?" "Do you want to put it to an executive vote?" "No--I can see that I'll lose. I want to put it before the entire membership."